Overview of the MECP Program The Mobile Electronics Certified Professional (MECP) program is owned and operated by the Consumer Electronics Association (CEA). The program started in 1991 and serves as the only industry‐wide automotive electronics certifications program in the world. Since its founding, MECP has certified over 40,000 professionals and currently boasts over 3,900 active certifications. MECP‐certified professionals can be found in installation bays, retail outlets, and with electronics manufacturers throughout the United States and around the world. Levels of MECP Certification  Basic Installation Technician: The MECP Basic level is meant as an “apprentice level” certification for those that have limited or no experience in the automotive electronics industry. The intent of this certification is to demonstrate a candidate's ability to understand the fundamentals required on the job. It is expected that the individual will follow the exam by gaining on‐the‐job experience and challenge themselves to move on to the next level. This certification is valid for two (2) years.  Advanced Installation Technician: The MECP Advanced level is intended for technicians who have at least one year of on‐the‐job professional experience in automotive electronics. This certification level covers a greater depth of electronics and vehicle electrical systems, installation knowledge and technique, mobile audio and video systems, security and remote starters, in vehicle information systems, troubleshooting installations and more. This certification is valid for four (4) years.  Master Installation Technician: The MECP Master level is meant to distinguish the “best of the best” in automotive electronics. This level requires three years of on‐the‐job experience and covers the electrical and troubleshooting aspects of the discipline, including Master‐level troubleshooting, audio, electronic components, OEM audio and video integration, security/remote start, wireless communications with modern technologies, and vehicle electrical systems. This certification is valid for four (4) years.  Mobile Product Specialist (MPS): The MECP Mobile Product Specialist (MPS) Certification is for sales professionals in the industry. The purpose of this certification is to help sales people and installation technicians see eye‐to‐eye on many technical issues. This certification is intended to empower the sales people who go beyond the act of "selling boxes" to understand system design, some very basic electrical concepts, audio, video, security, remote starters, and navigation, as well as identifying what customers are Guide Prometric Proctored Level telling them. This certification is valid for four (4) Cost Test Cost Test Cost years. Basic $35 $85 $60 Advanced $55 $105 $80 Master $75 $125 $100 MECP Testing MPS
$35
$85
$60
For each level of certification, there is a corresponding study guide and exam. Technicians are encouraged to purchase a study guide as this is the most effective way to study for and pass an exam. Passing the MECP exam with a score of 70 or better on each section is required to achieve certification. There are two ways to take an MECP exam. Technicians can make an appointment at any one of thousands of Prometric testing centers throughout the US. Technicians also have the option of arranging for a proctored test at an industry training school, public library or similar location. Test takers wishing to take a proctored test should contact mecp@mecp.com for more information. MECP tests are 100% supervised and computer‐based. Contact MECP Any questions about MECP should be e‐mailed to mecp@mecp.com. Answers to many basic questions can be found on our website at www.mecp.com. Study Guide Sample Pages Basic Installation Technician Study Guide Table of contents
Introduction
MECP Basic Installation Technician Study Guide Introduction.......12
Job Descripton – MECP Basic Installation Technician ....................13
What is an MECP Basic Installation Technician…
And What Does it Mean to You?.....................................................17
The MECP Basic Installation Technician Exam
and How it was Developed..............................................................19
How and Where to Take MECP Exams...........................................21
Reading the Study Guide and Preparing for the Exam.....................23
Notes About Registering, Scheduling, Rescheduling, or
Cancelling an MECP Exam..............................................................24
How to Take the Exam....................................................................28
After the Exam.................................................................................29
Records Transfer..............................................................................30
MECP Database Access....................................................................30
Contacting MECP............................................................................33
CHAPTER 1. BASIC ELECTRONICS AND VEHICLE ELECTRICAL SYSTEMS
Electrical Circuit Basics...................................................................36
Understanding Voltage, Current and Resistance..............................38
Series and Parallel Total Resistance Formulas . ...............................50
Electrical Power (Watt’s Law)..........................................................54
Ohm’s Law Quick Reference............................................................59
Kirchhoff’s Laws..............................................................................60
Electronic Components ..................................................................66
Batteries as a Voltage Source...............................................66
Switches ...........................................................................67
Resistors ............................................................................69
Potentiometers....................................................................72
Incandescent Light Bulbs....................................................73
Capacitors...........................................................................75
Inductors ...........................................................................78
Relays ...............................................................................81
Semiconductors .................................................................86
Diodes ...............................................................................87
Light Emitting Diodes.........................................................89
Automotive Electrical Power Supply and Charging Systems............90
The Battery ........................................................................90
The Alternator ...................................................................93
The Fuse Panel....................................................................97
The Ignition Switch ...........................................................99
Low Current Ignition Circuits.............................................102
Fuses and Circuit Breakers ................................................103
Choosing and Installing High Current Power Cables .........109
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Remember BOTH sides of the circuit
(Upgrading Grounds)..........................................................113
Importance of using a grommet when passing
through metal ....................................................................113
Power Storage Capacitors ..................................................113
Sample Test Questions for Chapter 1 .............................................116
CHAPTER 2. ENTRY-LEVEL Installation Knowledge AND Technique
Tools and Safety................................................................................................... 120
Hand Tools......................................................................................120
Specialty Installation Tools..............................................................124
Large Power and Pneumatic Tools...................................................130
Shop Safety......................................................................................131
Personal Safety.................................................................................131
Chemical Safety...............................................................................134
Fire Extinguishers............................................................................137
Keeping a Clean Shop.....................................................................139
Pre-Installation Guidelines and General Vehicle Disassembly..........140
Electronic Testing and Test Equipment...........................................147
Digital Multimeter (DMM)..................................................147
Test Lights (not recommended)..........................................150
Testing Wires/Circuits in a Vehicle.....................................154
Cautions of “Tapping In” to Low Current Ignition Systems.....166
General Installation Knowledge............................................................................ 167
Importance of Making Proper Connections.....................................167
Common Connection Types............................................................167
MECP Best Practices for Making Low and High Current Connections....185
Low Current Termination Techniques................................185
High Current Termination Techniques...............................186
Troubleshooting Common Installation Problems................................................... 187
Identify-Isolate-Eliminate …..The path to thinking it through!.......189
Testing Voltage Drops.....................................................................194
Short Circuits..................................................................................200
Open Circuits..................................................................................203
Blown Fuses....................................................................................204
Battery Mysteriously Drains.............................................................205
Understanding Wiring Diagrams – Vehicle Schematics...................206
Understanding Wiring Diagrams – Aftermarket Products................209
Sample Test Questions for Chapter 2..............................................211
Table of contents
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CHAPTER 3. INTRODUCTION TO MOBILE AUDIO/VIDEO SYSTEMS
Basics of Sound.................................................................................................... 214
Components of a Sound Wave........................................................214
Phase and Polarity...........................................................................219
Resonance........................................................................................222
Frequency Response – Where System Design Philosophies Begin...223
Filtering – Routing the signals to the right speakers........................226
Octaves and Harmonics...................................................................231
Signal to Noise Ratio (S/N)..............................................................236
Headroom.......................................................................................238
General Mobile Audio Installation Knowledge...................................................... 239
Overview of In-Dash Headunit Installation Best Practices................239
DIN and Double DIN Aftermarket Form Factors................240
Dash Kits............................................................................242
Wiring Harness Adaptors....................................................243
Antenna Adaptors...............................................................246
Important Integration Devices.............................................248
Overview of OEM Source Unit Retention........................................251
Adding Other Sources.........................................................252
Adding Amplifiers/Upgrading the Sound.........................................257
Line Output Converters......................................................257
Summing Devices...............................................................259
Turn-on Lead Issues...........................................................260
Application Specific Integration Devices
– such as CAN bus, MOST apps.........................................262
MECP Best Practices for OEM Integration.......................................263
Overview of Preamp Level Processors..............................................264
Overview of Aftermarket Amplifier Installation Best Practices.........271
Setting the Input Gain (Simply, but Correctly)................................283
Overview of Replacement Speaker Installation Best Practices..........289
Observing Correct Speaker Polarity Connections................291
Proper Speaker Mounting...................................................292
Importance of Damping Vibrations and Resonant Panels....296
Installing the Passive Crossover on Component Speakers...299
Overview of Subwoofer Enclosures.................................................301
Why Subwoofers Need Enclosures......................................301
Basic Benefits/Drawbacks of Sealed and Vented Designs.....301
Calculating Volume.............................................................303
Construction Materials/Methods.........................................308
General Mobile Video Installation Knowledge.................................311
Overview of In-Dash Video vs. Rear Seat Entertainment.....311
In-dash or Driver Viewed Video.........................................312
In-Dash or “Driver Viewed” Monitors.................................313
Overhead Monitors.............................................................314
Headrest/Seat Back..............................................................315
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Floor/Center Console..........................................................317
Running any 120VAC Devices............................................317
Wireless Headphones..........................................................318
Troubleshooting Common Mobile Audio System Installation Problems................. 320
Identifying and Troubleshooting Audio System Noise.....................320
System Noises.....................................................................320
Limited Bass Response........................................................320
Enclosure Construction.......................................................321
Polarity Conflicts................................................................321
Position of subwoofer vs. other speakers............................321
Power Problems..................................................................323
Distortion at High Volumes................................................324
Clipping..............................................................................324
Voltage Drops.....................................................................326
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CHAPTER 4. INTRODUCTION TO SECURITY AND CONVENIENCE SYSTEMS
Remote Controls and RF.................................................................332
Basic Components of a Security System...........................................333
Inputs and Outputs of a Security System............................333
Sounding Devices...............................................................340
Visual Deterrents.................................................................341
Sensors................................................................................342
Engine Disables...................................................................345
LED (Status Indicator)........................................................347
Valet Switch........................................................................348
Backup Battery or Backup Battery Siren..............................349
Accessory Output Devices...................................................351
Using Relays.......................................................................352
Basic Components of a Remote Starter............................................355
Inputs and Outputs of a Remote Starter..............................355
Bypassing Transponder Keys...............................................359
Initial Programming or Updating Firmware on Interface
Devices...............................................................................361
Safety Measures...................................................................362
Applications and Requirements for Remote Starters............364
Identifying Vehicle Circuits.............................................................365
Identify Positive Switching..................................................365
Identify Negative Switching................................................365
Identify Reverse Polarity Switching.....................................365
Identify Multiplex or Variable Voltage Switching................366
Basic Installation Tips......................................................................368
Preparing for the Installation..............................................368
Mounting Considerations for a Control Unit......................369
Wiring and Connections for the Control Unit.....................370
Tips on Performing the Installation.....................................372
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Troubleshooting Basic Security and Remote Starter System Installation
Problems.........................................................................................373
Remote does not respond...................................................374
Security System Randomly Triggers....................................377
Other Basic Security System/Remote Starter Troubleshooting
Tips.....................................................................................380
Sample Test Questions for Chapter 4..............................................382
CHAPTER 5. INTRODUCTION TO IN-VEHICLE INFORMATION
AND SAFETY SYSTEMS
Broadcast Entertainment..................................................................387
In-Band On-Channel (IBOC) Digital AM/FM Radio............387
Satellite Radio.....................................................................389
Introduction to Bluetooth Hands Free Communication..................401
Bluetooth Basics..................................................................401
Bluetooth Hands Free Communication Devices and Installation.....406
Hands Free Capability and Installation Kits........................406
Introduction to Navigation and Safety Related Systems...................412
How the GPS Satellites Work..............................................412
How and Where to Place GPS Navigation Antenna.............413
Rear View Camera Systems.................................................414
Reverse Sensor Systems.......................................................417
How to identify a reverse trigger input...............................418
Front View Camera Systems...............................................418
Sample Test Questions for Chapter 5..............................................420
Glossary of Terms................................................................................424
APPENDIX...................................................................................................462
RESOURCES FOR ADDITIONAL READING. ................................................467
Acknowledgements, Trademarks, etc...........................................468
index..........................................................................................................471
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even caller ID functionality. Instead of just talking and listening, the HFP allows
more control and access to the phone.
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The difference between HP and HFP
In the past, there was no universal way for Bluetooth mobile phones and handsfree car kit systems to share enhanced information (such as voice dialing, address
books, battery indicator, network signal strength, etc.) beyond the call itself. This
made implementation of integrated features difficult for OEM vehicle manufacturers. Aftermarket solutions were slow to develop too, either because of cost or
complexity.
Just about every car manufacturer offers Bluetooth hands-free profile (HFP) solutions as an option, if not as standard equipment. Aftermarket in-car hands free
Bluetooth solutions (for virtually any make or model of car) are also available
from a variety of manufacturers, including Auto Page, Motorola, EGO, Nokia,
Parrot, Scosche, NAV-TV, Sony Ericsson and others, some of which are HFP
supported, not just HP (talk and listen) kits. The key is to check the fine print or
technical specifications to know for sure.
With a Bluetooth-enabled phone used in a factory supplied HFP set up, once
inside the vehicle the driver generally only has to have their cell phone ON after
the initial pairing. The phone typically links up with the Bluetooth HFP module
in the car automatically. If multiple phones are paired, it may ask which you want
to connect or it may default to the last connected phone.
For speech recognition, the driver’s voice projects through a factory-installed
microphone (generally located in the rearview mirror, overhead console, or
A-pillar area) and broadcasts hands-free conversation through the vehicle’s OEM
sound system (generally the driver’s side speakers). Many systems that are factory
installed are voice activated to maintain a completely hands-free system from
selecting the number to dial straight through the end of the call. This is a major
consideration when adding aftermarket amplifiers and speakers to these vehicles
as it’s sometimes the case that this Bluetooth HFP functionality for the audio input
and output “lives” inside of the OEM amplifier, in which case removal is not a
viable (or sensible) option.
Many aftermarket HFP kits work in a similar manner to the OEM functionality; however, the equipment design and location are different. In particular, it
depends on if it’s a universal product with a separate control panel/display or if
Chapter 5. Introduction to in-vehicle information and safety systems
403
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n
Figure 213. Sealed
enclosure design (also
called “air suspension”
or “acoustic suspension”
designs)
of enclosures. Some are better suited for one environment or the other. It’s always
best to contact the manufacturer or read technical support resources to see what’s
recommended for any particular subwoofer.
The sealed enclosure is also referred to as air-suspension or acoustic-suspension. The sealed box is the easiest type of subwoofer enclosure to design and
build, which makes this a good all around design if the subwoofer is suited for a
sealed enclosure environment. The idea behind a sealed enclosure design is that
the air trapped inside the box will work to assist the speaker’s suspension, which
gives us the term air-suspension. As the speaker moves outward, the air behind
it is pulled with it, creating a decrease in pressure inside the box. This acts like a
vacuum and pulls the speaker back inward. Similarly, when the speaker moves
in, the air that is compressed pushes out on the speaker. Logically, the more the
speaker moves in or out, the greater these forces are. If the speaker were designed
with a loose suspension and a long excursion, the sealed enclosure would provide
smooth bass response, since the stiffer air pressure within the enclosure would
control speaker excursions.
n
Benefits of Sealed Enclosure Designs – Box volume is small in comparison to other enclosure types. Good output for all music types. Easy
to build and tolerant of small errors in calculation of volume or if you
forget to subtract volume for a brace, etc. Many well built pre-fabricated
sealed enclosures available offer good results.
n
Drawbacks of Sealed Enclosure Designs – Poor response below 30 Hz
when compared with a vented enclosure. Low-end response gets worse
as enclosure size decreases. Typically requires more power for a given
output when compared to a vented enclosure.
Vented enclosures are also called ported enclosures or bass-reflex enclosures. It
adds a vent through which air resonates in tune with the speaker at the enclosure’s resonant frequency, effectively increasing the output. You can hear the
principle of vented box design at work by simply blowing air across the opening
of a filled soda bottle. In this case the tuning hole is fixed, but you can change
the length of the vent by taking a drink. Blowing air again, you will hear a lower
pitch. If you could alter the size of the opening or use a different size bottle altogether, the pitch would also change.
Vented enclosures are more complicated to design than sealed enclosures. There
is a delicate relationship between the enclosure size (box volume), port size (both
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5. According to the MECP Basic Installation Technician study guide, when
measuring a low current (MUX) ignition circuit, what setting of the DMM
is used to determine the various values of each key switch position?
a) AC Volts.
b) DC Volts.
c) Ohms.
d) Continuity.
6. How should the jaw of a crimp tool be positioned in reference to the seam
of the crimp connector?
a) The jaw should face away from the connector’s seam.
b) The jaw should be positioned on the connector’s seam.
c) The jaw should not be used at all with seamed crimp connectors.
d) The position of the jaw is irrelevant in seamed crimp connectors.
7. For in vehicle measurements, test lights are recommended by MECP
because they always provide a measured, numeric value to the technician?
a) True.
b) False.
8. What are the 3 MECP recommended steps to troubleshooting noise problems:
a) Insulate, Evaluate, Innovate.
b) Isolate, Evaluate, Insulate.
c) Identify, Insulate, Innovate.
d) Identify, Isolate, Eliminate.
9. Testing for blown electrical system fuses in a vehicle fuse panel should be
done with which setting on the DMM?
a) AC Volts.
b) DC Volts.
c) Ohms.
d) Continuity.
10. What does the blue section of the NFPA 704 Diamond represent with
respect to safety considerations?
a) Health.
b) Fire.
c) Reactivity.
d) Special Information.
Answers to Chapter 2 Questions
1. B, 2. A, 3. A, 4. D, 5. C, 6. A, 7. B, 8. D, 9. B, 10. A
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n
Floors should be swept as often as possible. Stray screws can easily find
their way into tires and cause tire problems. The last thing you want is to
be responsible for a customer’s flat tire (particularly with the high cost of
some high end performance tires).
n
Reels of wire/cable should be put back on their racks and stored in an
orderly fashion.
n
Boxes that equipment came in should be put in the owner’s car or properly recycled.
n
Promptly clean up metal chips from power nibblers or metal cutting
other tools. Never leave them on the floor to be swept up later, or these
chips can find their way into customers’ tires, the interior of their cars
and the bottoms of your shoes. You can use old speaker magnets to easily
pick up stray nibbler chips or small metal shavings and keep them from
being tracked all over the shop.
n
A heavy-duty shop vacuum is essential for cleaning up the floor and the
vehicle’s carpets, particularly with small bits of wire or insulation that
inevitably end up on the floor carpet.
n
Whenever possible, do wood working or any other fabrication in a separate, ventilated area so unnecessary dust is not settling on the vehicle.
n
Always leave a customer’s vehicle cleaner than you found it.
Pre-Installation Guidelines and General Vehicle Disassembly
Everyone has habits. Some of them are good and some of them are not so good.
MECP best practices are about establishing good habits in the shop that can save
time and money as well as assuring a positive customer experience. MECP installation technicians should exemplify professionalism in everything they do.
Before Beginning the Install
The installation process actually begins long before a vehicle enters the shop. It is
a cooperative effort between the sales staff as well as the installation staff. The process begins when a consumer enters the store. Before attempting to sell anything,
the MECP certified sales associate should check their database to learn everything
necessary about the customer’s vehicle (see the next paragraph for details). The
associate should know about vehicle wiring specifications, interface issues, and
anything that may require additional parts, labor, or other considerations before
attempting to sell a customer anything. Depending on the shop’s policies, the
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for security and remote starter interface applications, you will often find that 5%
or even 1% tolerances are recommended to avoid intermittent circuit behavior
caused by out of range values.
n
Margin Notes
Figure 34. The resistor color code chart indicates the resistance and tolerance of 2 watt or
smaller carbon resistors
Since resistors almost always open (break the circuit) when they go bad, troubleshooting resistive problems is pretty straight forward. An open resistor in a series
circuit will stop current from flowing in the circuit. An open resistor in a parallel
circuit will increase the circuit resistance and decrease the total current.
Schematically, a resistor is represented by zig-zag lines that straighten out at either
end. When there are multiple resistors in a circuit, they are assigned the letter “R” with
a subscript number (such as R1, R2, R3, etc.) just like the characteristic of resistance.
While the resistor schematic represents a specific component, resistance that does
not come from a resistor can appear in the circuit path from things like poor
connections, corrosion, etc., that should not be there under normal operational
circumstances. In some cases for problem solving, the symbol for the resistor may
Chapter 1. BASIC ELECTRONICS AND VEHICLE ELECTRICAL SYSTEMS
71
An atom for electrical purposes breaks down like this:
n
The center of an atom is the nucleus.
n
Nucleus contains protons (positive charge) and neutrons (neutral
Margin Notes
charge).
n
The outer parts of the atom contain electrons (negative charge).
n
The outermost orbit of are called valence electrons.
n
Ions ARE atoms except they are atoms with either extra electrons or
missing electrons.
n
An ion will exhibit the charge of the parts that are greater (positive if
more protons, negative if more electrons).
n
Valence electrons are easiest to “break away” and change the charge of the
atom left behind. These are called free electrons.
n
When valence electrons leave an atom, the ion becomes positively
charged and “attracted to” free electrons
n
When negatively charged electrons move to the next ion with an open
spot that the previous electron left behind, this is how electricity begins
to move in a circuit. This gets repeated over and over.
n
Figure 2. Electrons moving from one atom to another is how electricity moves in a circuit.
Electricity simply means electrons moving. Once you have that basic idea down,
you’re one step closer to understanding the puzzle in electrical circuit behavior.
At this point it’s really just the details of what terms describe how the circuit
performs and moves electrons in a path from beginning to end. Electrons moving are really what electrical circuits are all about. When, how, how much, and
why those electrons move or don’t move is all part of this chapter. Sounds a little
complicated at first, but really it’s not.
Chapter 1. BASIC ELECTRONICS AND VEHICLE ELECTRICAL SYSTEMS
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Advanced Installation Technician Study Guide TABLE OF CONTENTS
HEADLINE
Introduction.................................................................................................................................... 13
Contacting MECP .................................................................................................................... 36
CHAPTER 1 — ADVANCED ELECTRONICS AND VEHICLE ELECTRICAL SYSTEMS
History of Vehicle Electronics ......................................................................................................... 40
Electrical Circuit Fundamentals ...................................................................................................... 40
Understanding Voltage, Current and Resistance............................................................................. 42
The Relationship of Voltage, Current, and Resistance (Ohm’s Law) ....................................... 42
Calculating Series and Parallel Resistance ................................................................................ 53
Ohm’s Law and Electrical Power (Watt’s Law) ............................................................................... 57
Law of Conservation of Energy................................................................................................ 58
Watt’s Law ............................................................................................................................... 59
Kirchhoff’s Laws ............................................................................................................................. 63
Kirchhoff’s Voltage Law ........................................................................................................... 63
Kirchhoff’s Current Law .......................................................................................................... 65
Which way does DC Current really flow? ............................................................................... 67
Applications of Electronic Components ......................................................................................... 68
Batteries as a Voltage Source.................................................................................................... 69
Switches................................................................................................................................... 70
Resistors................................................................................................................................... 72
Potentiometers ......................................................................................................................... 78
Incandescent Light Bulbs ......................................................................................................... 80
Capacitors ................................................................................................................................ 81
Inductors ................................................................................................................................. 87
Relays....................................................................................................................................... 94
Semiconductors ..................................................................................................................... 101
Diodes ............................................................................................................................. 103
Light Emitting Diodes (LED’s)......................................................................................... 107
Transistors ....................................................................................................................... 109
Integrated Circuits (IC’s) ................................................................................................. 114
Microprocessors .............................................................................................................. 115
Automotive Electrical Power Supply and Charging Systems ........................................................ 115
The Automotive Battery ......................................................................................................... 116
The Alternator ....................................................................................................................... 124
The Fuse/Power Distribution Panel ....................................................................................... 127
The Ignition Switch ............................................................................................................... 130
Traditional Ignition Circuits .................................................................................................. 130
Low Current Ignition Circuits ............................................................................................... 132
Fuses and Circuit Breakers .................................................................................................... 133
Choosing and Installing High Current Power Cables ............................................................ 140
Power Storage Capacitors ...................................................................................................... 143
Bringing it all Together – System Architecture and Design .......................................................... 146
The Electrical System Backbone ............................................................................................ 146
The Process of Evaluation in a Design ................................................................................... 150
Best Practices Choosing Power Cables for Everyday Installations.......................................... 160
Digital Fundamentals .................................................................................................................... 164
Data-bus Communications .................................................................................................... 164
Control Modules and Diagnostic System Acronyms.............................................................. 165
Multiplexing .......................................................................................................................... 165
The Binary System ................................................................................................................. 167
Integration into a Databus ..................................................................................................... 170
D2B (Domestic Digital Bus)............................................................................................. 173
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THE ADVANCED INSTALLATION TECHNICIAN STUDY GUIDE
Class 2 (General Motors) ................................................................................................. 174
CAN BUS ........................................................................................................................ 175
MOST .............................................................................................................................. 181
Installation Related Databus Tips .......................................................................................... 185
Sample Test Questions ................................................................................................................. 187
CHAPTER 2 — ADVANCED INSTALLATION KNOWLEDGE AND TECHNIQUE
Professionalism ............................................................................................................................. 192
Installation Guidelines – Best Practices Before, During and After ................................................. 193
Safety and Tools............................................................................................................................ 198
Personal Safety ....................................................................................................................... 199
Chemical Safety ..................................................................................................................... 201
Fire Extinguishers .................................................................................................................. 204
Keeping a Clean Shop ........................................................................................................... 207
Tools ............................................................................................................................................. 207
Hand Tools ............................................................................................................................ 208
Specialty Installation Tools .................................................................................................... 213
Electrical Measurement Tools ................................................................................................ 219
Digital Multimeter (DMM) .............................................................................................. 220
Test Lights and why they are not recommended ............................................................ 225
Oscilloscopes ................................................................................................................... 229
Test Leads and Probes ..................................................................................................... 236
Hall-Effect Current Clamp .............................................................................................. 238
Polarity Tester ................................................................................................................. 239
Real Time Analyzer (RTA) ............................................................................................... 240
Power and Pneumatic Tools .................................................................................................. 242
General Vehicle Disassembly ........................................................................................................ 247
Use of Proper Tools ............................................................................................................... 247
Interior Panel Evaluation and Removal ................................................................................. 248
Electronic Testing and Test Equipment ........................................................................................ 252
Understanding Wiring Diagrams – Vehicle Schematics......................................................... 256
Testing Wires in a Vehicle ..................................................................................................... 263
Taking DC Voltage Measurements .................................................................................. 264
Taking AC Voltage Measurements................................................................................... 267
Taking Resistance Measurements .................................................................................... 269
Checking Continuity ....................................................................................................... 271
Taking Standby (Parasitic) Current Draw Measurements................................................ 272
Taking High Current Measurements with a Hall Effect Clamp ....................................... 275
Specific Vehicle Electrical Tests .................................................................................................... 277
Battery and Charging System Testing .................................................................................... 277
State of Health (SOH) Test with a DMM and Hall-Effect Clamp .................................... 287
Low Current (MUX) Ignition System Testing ........................................................................ 298
Tachometer Signal Testing..................................................................................................... 300
Vehicle Speed Sensor (VSS) Testing ...................................................................................... 302
Audio Output Testing............................................................................................................ 304
NTSC Video Signal Testing ................................................................................................... 308
Databus Testing (Copper Wires) ........................................................................................... 312
Testing Voltage Drops ........................................................................................................... 315
Short Circuit Testing ............................................................................................................. 321
Open Circuit Testing ............................................................................................................. 323
Troubleshooting Installation Problems ......................................................................................... 323
Identify-Isolate-Eliminate…The path to thinking it through!................................................ 325
CHAPTER
TABLE
OF CONTENTS
5
Powerline Noise .............................................................................................................. 328
Radiated Noise ................................................................................................................ 330
Ground Loop Noise......................................................................................................... 332
Accessory Noises ............................................................................................................. 334
System Noises..................................................................................................................334
General Installation Knowledge .................................................................................................... 335
Importance of Making Proper Connections........................................................................... 335
Soldering ......................................................................................................................... 335
Crimping (Butt Connectors)............................................................................................ 337
Connection Types Not Recommended............................................................................ 338
MECP Best Practices for Making Low and High Current Connections ................................. 339
Proper Speaker Mounting...................................................................................................... 341
Noise Control ........................................................................................................................ 346
Basics of Aftermarket Amplifier Installation.................................................................................. 349
Getting power at the battery (or direct battery feed) ............................................................. 349
Grounding (especially in Uni-body Cars) .............................................................................. 350
Getting Signal into the Aftermarket Amplifier ....................................................................... 352
Speaker Connections to an Amplifier Channel...................................................................... 353
Understanding the Function of Input Gain Adjustment........................................................ 356
Amplifier Mounting Location ................................................................................................ 371
Sample Test Questions ................................................................................................................. 373
CHAPTER 3 — ADVANCED MOBILE AUDIO/VIDEO SYSTEMS
Vehicle Disassembly for Audio and Video System Installations.................................................... 378
Audio and Video Source Formats ................................................................................................. 384
Analog AM/FM Radio ............................................................................................................ 384
Digital AM/FM Radio ............................................................................................................. 386
Digital Satellite Radio............................................................................................................. 386
Disc Formats.......................................................................................................................... 387
CD — Compact Disc ...................................................................................................... 387
HDCD ............................................................................................................................. 388
DVD-Video ...................................................................................................................... 389
DVD-Audio ..................................................................................................................... 389
SACD............................................................................................................................... 390
Blu-ray Disc ..................................................................................................................... 391
Older Source Format Technologies ....................................................................................... 396
Digital Music Files ................................................................................................................. 394
Lossy and Lossless Audio Compression .......................................................................... 396
Compression of Digital Audio Files – How it’s Done ...................................................... 399
Perceptual Coding ........................................................................................................... 399
Haas Effect....................................................................................................................... 400
Recommended Bit Rates for Lossy Audio Compression .................................................. 401
Mobile Audio Source Units........................................................................................................... 401
Head Unit Mounting Types ................................................................................................... 401
Source Unit Audio Output Types (Analog and Digital)......................................................... 404
Source Unit Audio Output Characteristics ............................................................................ 409
Signal to Noise Ratio (S/N) .............................................................................................. 409
Preamp Output Voltage................................................................................................... 410
Output Impedance .......................................................................................................... 410
External Source Inputs .......................................................................................................... 411
Steering Wheel Control (SWC) Adapters .............................................................................. 416
Analog SWC .................................................................................................................... 416
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THE ADVANCED INSTALLATION TECHNICIAN STUDY GUIDE
Digital SWC .................................................................................................................... 417
Head Unit Installation Specific Considerations ..................................................................... 420
Audio Signal Processing................................................................................................................ 425
What is Signal Processing? .................................................................................................... 425
Analog vs. Digital Signal Processing ...................................................................................... 425
Preamp Equalizer................................................................................................................... 428
Graphic EQ ..................................................................................................................... 429
Parametric EQ ................................................................................................................. 430
Active Crossovers................................................................................................................... 431
“Q” and Slopes....................................................................................................................... 432
Decoders for Multi-channel Audio Formats .......................................................................... 433
Installation Specific Signal Processing Considerations ........................................................... 434
Audio Signals in OEM Systems..................................................................................................... 438
Stumbling Blocks for The Aftermarket .................................................................................. 438
Technician Knowledge .......................................................................................................... 439
OEM Audio Signal Voltage Level .................................................................................... 440
OEM Audio Signal Reference Ground............................................................................. 442
OEM Audio Channel Bandwidth Limitations.................................................................. 443
OEM Audio Channel Equalization Curve(s) ................................................................... 444
OEM Interface Devices ................................................................................................................. 445
Input Devices......................................................................................................................... 446
Output Devices ...................................................................................................................... 450
OEM Integration Installation Specific Considerations ........................................................... 458
Analyzing OEM Audio Signal Characteristics ........................................................................ 460
Mobile Audio Amplifiers............................................................................................................... 465
Power Supply Section ............................................................................................................ 465
Audio Section ........................................................................................................................ 466
Channel Configurations......................................................................................................... 466
Mobile Audio Amplifier Circuit Topologies........................................................................... 471
Amplifier Power Terminology ............................................................................................... 479
Passive Crossover Networks ......................................................................................................... 482
Construction of a Crossover .................................................................................................. 484
Orders of Response ......................................................................................................... 488
Speaker Installation ...................................................................................................................... 489
Speaker Types........................................................................................................................ 489
Subwoofer Enclosures................................................................................................................... 491
Calculating Volume ............................................................................................................... 493
Enclosure Construction ......................................................................................................... 498
Infinite Baffle Designs ............................................................................................................ 503
Semi Closed Aperiodic Designs ............................................................................................. 506
Sealed Enclosure Designs ...................................................................................................... 507
Vented Enclosure Designs ..................................................................................................... 511
Bandpass Enclosure Characteristics ....................................................................................... 518
Single Reflex Bandpass Designs ............................................................................................. 519
Dual Reflex Bandpass Design................................................................................................. 520
Transmission Line / Quarter Wave Designs........................................................................... 522
Sound in the Vehicle .................................................................................................................... 524
Low Frequency Transfer Function ........................................................................................ 524
Uninvited Noises ................................................................................................................... 525
Importance of Damping Vibrations and Resonant Panels...................................................... 526
Speed of Sound ..................................................................................................................... 527
Speaker Positioning and Installation ............................................................................................. 527
CHAPTER
TABLE
OF CONTENTS
7
Positioning Speakers for Optimum Performance................................................................... 532
Mobile Video Entertainment Systems ........................................................................................... 541
Review ................................................................................................................................... 541
Video Sources ........................................................................................................................ 543
Video Screens ........................................................................................................................ 547
Mobile Video Input/Output Formats ..................................................................................... 549
Analog Composite Video Output (The Yellow RCA Plug) .................................................... 549
Analog RGB – Red/Green/Blue .............................................................................................. 552
Digital Mobile Video Formats ................................................................................................ 555
Mobile Video System Installation Considerations.................................................................. 560
Mobile Video Installation Safety ............................................................................................ 560
Infrared and RF Wireless Headphone Systems ...................................................................... 567
DC-AC Power Inverters ......................................................................................................... 567
Troubleshooting Common Video System Installation Problems ........................................... 570
Sample Test Questions ................................................................................................................. 573
CHAPTER 4 — ADVANCED SECURITY AND CONVENIENCE SYSTEMS
Vehicle Disassembly for Security and Convenience Installations.................................................. 579
OEM Anti-Theft Systems .............................................................................................................. 580
Identifying an OEM Anti-Theft system .................................................................................. 580
Keyless Entry / Security System Misconceptions ................................................................... 582
Advanced Security Topics............................................................................................................. 583
Range and RF Interference .................................................................................................... 584
Inputs and Outputs of a Security System .............................................................................. 587
Identifying Vehicle Circuits .......................................................................................................... 591
Identify Positive Switching .................................................................................................... 593
Identify Negative Switching ................................................................................................... 593
Identify Reverse Polarity Switching ....................................................................................... 595
Identify Multiplex or Variable Voltage Switching .................................................................. 596
True Variable Voltage Switching ..................................................................................... 596
True Multiplex Switching (Unique Digital Messaging).................................................... 598
Identify High Speed or Medium Speed CAN Voltages .................................................... 601
Identify Low Speed, Fault Tolerant CAN Voltages .......................................................... 602
Identify Single Wire CAN Voltages ................................................................................. 603
Unique Interfacing Challenges............................................................................................... 604
Interior Lighting Circuits (included isolated zones, time delayed, etc.) .......................... 604
Special Application Door Lock Circuits .......................................................................... 605
Special Application Lighting Circuits (Some European Lighting Circuits) ...................... 607
Advanced Relay Applications........................................................................................................ 608
Inverting Polarity ................................................................................................................... 609
Amplify or Increase Current .................................................................................................. 609
Turning Something ON ......................................................................................................... 610
Turning Something OFF ....................................................................................................... 612
Dual Purpose Applications .................................................................................................... 612
Isolation ................................................................................................................................. 614
Wiring Relays ........................................................................................................................ 614
Security System Placement and Mounting .................................................................................... 617
Mounting Considerations for a Control Unit......................................................................... 617
RF Range Concerns ............................................................................................................... 617
Electromagnetic and Inductive Coupling Concerns .............................................................. 618
Vibration Concerns................................................................................................................ 619
Wiring and Connections for the Control Unit....................................................................... 620
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THE ADVANCED INSTALLATION TECHNICIAN STUDY GUIDE
Troubleshooting Common Security System Problems........................................................... 628
Security and Convenience System Accessories ............................................................................. 629
Long Range Notification and Communication ...................................................................... 629
Backup Power Sources .......................................................................................................... 632
Window and Sunroof Automation ........................................................................................ 633
Alternative Security System Applications ...................................................................................... 638
Boats ...................................................................................................................................... 638
Motorcycles and Snowmobiles .............................................................................................. 639
Tractors ................................................................................................................................. 639
Hybrid Gas-Electric Vehicles ................................................................................................. 639
Remote Start Systems.................................................................................................................... 640
Remote Starter System Overview ........................................................................................... 640
Remote Starter Vehicle Applications ...................................................................................... 644
Automatic and Fuel-Injected Vehicle Applications.......................................................... 644
Carbureted Applications.................................................................................................. 644
Manual Transmission Applications ................................................................................. 645
Diesel Applications .......................................................................................................... 646
Hybrid Gas-Electric Vehicles ........................................................................................... 647
Identifying Critical Remote Starter Connections........................................................................... 649
Ignition Switch Positions and Measurements ........................................................................ 649
Traditional Positive Switching Ignition Systems .............................................................. 650
Low Current Ignition Circuits ......................................................................................... 653
Databus Ignition Switches/Modules ................................................................................ 654
Push to Start (PTS) or Push Button Starting Systems ...................................................... 654
Parking Light Circuit ............................................................................................................. 658
Autolamp Circuit ................................................................................................................... 660
Tachometer Signal ................................................................................................................. 662
Fuel Injector Pulse Signal ...................................................................................................... 662
Alternator Signal (Voltage Change) ....................................................................................... 664
Foot Brake Switch.................................................................................................................. 664
Parking Brake Switch............................................................................................................. 665
Neutral Safety Switch ............................................................................................................ 665
Hood Pin Switch.................................................................................................................... 666
Clutch Switch ........................................................................................................................ 667
Rear Defrost (and other heated accessories) .......................................................................... 669
Status Output or Ground When Running (GWR)................................................................. 670
RAP Circuit............................................................................................................................ 671
Programmable Parameters for Remote Starters ...................................................................... 672
OEM Security Interface and Bypass for Remote Starters............................................................... 674
Disarming the Factory Security System ................................................................................. 674
OEM Anti-Theft Methods ...................................................................................................... 676
Resistor Keys (VATS, PASSkey I) .................................................................................... 676
PASSlock 1 & 2............................................................................................................... 678
Passive Transponder Based Immobilizers ........................................................................ 684
Active Transponder Based Immobilizers ......................................................................... 686
OEM Anti-Theft System Integration Modules............................................................................... 687
Safety Considerations While Installing a Remote Start System ..................................................... 695
Testing the Remote Starting System ...................................................................................... 695
Educating Customer on Responsible Use .............................................................................. 697
Troubleshooting Common Remote Starter Installation Problems ................................................. 697
Sample Test Questions ................................................................................................................. 703
CHAPTER
TABLE
OF CONTENTS
9
CHAPTER 5 — IN-VEHICLE INFORMATION AND CONTROL SYSTEMS
Information on the Move.............................................................................................................. 708
How Information on the Road Works ................................................................................... 709
Bringing Outside Data into the Vehicle via Satellite ..................................................................... 710
GPS Satellites ......................................................................................................................... 710
Subscriber Radio Satellites ..................................................................................................... 716
Proprietary Data Satellites ...................................................................................................... 716
Terrestrial Repeaters (of satellite signals) ............................................................................... 717
Data in and out of the Vehicle via Radio Frequency Networks .................................................... 717
Federal Oversight .................................................................................................................. 718
What are Proprietary Networks? ........................................................................................... 719
What are Subscriber Networks? ............................................................................................ 723
RF Communication Network Technology ............................................................................. 729
WiFi 101 ............................................................................................................................... 731
Mobile Hotspots .............................................................................................................. 732
Tethering a Phone ........................................................................................................... 732
Dedicated In-Vehicle WiFi .............................................................................................. 734
Bluetooth Communications .......................................................................................................... 735
Bluetooth Device Compatibility ............................................................................................. 735
The Primary Bluetooth Device Profiles .................................................................................. 737
Profiles Relating to Hands-Free Communications ................................................................. 738
Headset Profile (HP) ........................................................................................................ 738
Hands Free Profile (HFP) ................................................................................................ 738
Phone Book Access Profile (PBAP) .................................................................................. 739
Profiles Relating to Advanced Audio Entertainment .............................................................. 740
Advanced Audio Distribution Profile (A2DP).................................................................. 740
Audio Video Remote Control Profile (AVRCP) ............................................................... 741
Other Bluetooth Profiles ........................................................................................................ 742
Bluetooth Hands Free Communication Devices and Installation .......................................... 745
Hands Free Capability and Installation Kits .................................................................... 754
Hands Free Microphone.................................................................................................. 746
Enabling Functionality between the HF Car Kit and Phone ........................................... 749
Firmware Updates ........................................................................................................... 749
In-Vehicle Navigation and Route Guidance Systems .................................................................... 750
Core Purposes for Navigation ................................................................................................ 750
Navigation System Inputs ...................................................................................................... 752
GPS Satellite Data ............................................................................................................ 752
Gyroscope ....................................................................................................................... 752
Vehicle Speed Sensor ...................................................................................................... 753
Testing the VSS Circuit – Speed Pulse ............................................................................ 753
Testing the Route Guidance System ...................................................................................... 753
HD Radio and Digital Satellite Radio ............................................................................................ 755
In-Band On-Channel (IBOC) Digital AM/FM Radio .............................................................. 755
Satellite Radio ........................................................................................................................ 757
Installing Satellite Radio Antennas......................................................................................... 761
Mounting/Wiring Dedicated Receivers .................................................................................. 763
Troubleshooting Common Satellite Radio Problems ............................................................. 767
Integration and Interface with On-board Safety Systems .............................................................. 768
Safety Devices (General Overview) ........................................................................................ 768
FMVSS Review ................................................................................................................ 769
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THE ADVANCED INSTALLATION TECHNICIAN STUDY GUIDE
Tire Pressure Monitoring Systems (TPMS) ...................................................................... 772
OEM Rear View Cameras and Reverse Sensors ............................................................... 776
Aftermarket Rear View Mirrors ....................................................................................... 779
Radar and Laser Detection ............................................................................................................ 783
How Radar Detection Works................................................................................................. 784
How Laser Detection Works.................................................................................................. 785
Differences between Radar and Laser .................................................................................... 785
Minimizing Speeding – The Importance of Safety ................................................................. 789
Sample Test Questions ................................................................................................................. 790
Glossary ........................................................................................................................................ 794
Automotive Service Websites........................................................................................................ 842
Additional Reading Resources ...................................................................................................... 848
Index............................................................................................................................................. 852
CHAPTER
TABLE
OF CONTENTS
11
Margin Notes
Amplifier
6. What is the nominal impedance of the subwoofers shown as they are wired
to the amplifier?
a. 1 ohm
b. 2 ohms
Load
c. 4 ohms
at the
Amplifier?
d. 8 ohms
BRIDGED
Left +
(+)
(-)
2 Ohm
Left -
Right + Right -
(+)
(-)
2 Ohm
7. Which type of crossover listed is appropriate for a tweeter?
a. 3.5 kHz High Pass
b. 120Hz Low Pass
c. 400 Hz Notch Filter
d. 120Hz-3.5 kHz Bandpass
8. A subwoofer with an EBP of 37 indicates a vented (ported) enclosure is the
preferred enclosure?
a. True
b. False
9. What is the electrical power consumption of an amplifier drawing 15
amperes of current with a supply of 13.8 volts?
a. 92 Watts
b. 175 Watts
c. 205 Watts
d. 207 Watts
10. A customer complains of poor quality sound when listening to a portable
media audio device through a head unit you just installed. The problem
does not exist when listening to any other source. You also do not have the
problem when using an alternate portable media player connected the same
way. Which one of the following initial diagnoses is valid?
a. The head unit’s AUX input cable is defective and needs replacement
b. The audio files on the media player are highly compressed
c. One or more speakers are blown and they need to be replaced
d. One or more speaker wires are shorted and need replacement
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THE ADVANCED INSTALLATION TECHNICIAN STUDY GUIDE
in different ways for different applications. For example, a four-channel amplifier can have two channels bridged while the remaining two channels operate in
stereo. This creates a three-channel system. A six-channel amplifier can have two
channels bridged while the remaining four operate in stereo. You can accomplish
any number of combinations with multi-channel amps. For example, you can use
a four-channel amp in three-channel mode, where the low pass crossover sends
bass to the mono channel for subwoofer input, while the remaining stereo signal
drives a pair of components in the doors in a high pass mode.
Margin Notes
2,4, and 6 Channel Amplifier Default Configurations
Bridging Channels
Two main factors limit the output power in a common two-channel mobile audio
power amplifier:
Q The impedance of the speaker(s) connected to the amplifier
Q The internal power supply voltage
An amplifier’s bridging
capabilities depend upon
the load impedance
connected to the output
terminals and internal
power supply voltage.
CHAPTER 3. ADVANCED MOBILE AUDIO/VIDEO SYSTEMS
467
way the audio system will maintain a better quality of sound over the entire range
of useable volume.
Margin Notes
The other concern is that with increases in the gain overlap, a more notable
“hiss” to the system becomes noticeable with the volume all the way down. It’s
best to limit any gain overlap to 10dB or less for this reason. MECP recommends
+5-6dB of overlap on amplifiers connected to mid/tweeter components (only
if needed) and not more than +10dB of overlap on subwoofer amplifiers.
If the mid/tweeter component amplifiers are already powerful and don’t really
need added gain, the benefit to you is that leaving the adjustments at 0dB with
no overlap will keep any amplifier hiss (also called “floor noise”) to an absolute
minimum. Keeping a very low noise floor with a high dynamic range is why some
mobile audio systems use a bigger amplifier on mid/high speakers, but leave the
extra power in “reserve” for when the music demands those big peaks of power.
Amplifier Mounting Location
Choosing an amplifier mounting location has many more variables than simply
where it will fit and look good. Amplifiers in modern vehicles must be able to
adequately dissipate heat while maintaining a safe distance from sensitive electrical system components. In addition, amplifiers must be placed out of harm’s way
so that the heat sink is not covered by packages in a trunk or the electronics are
not damaged by an accidental spill.
Avoid mounting amplifiers upside-down because the heat transferred into the
heat sink has no way to dissipate. When mounted upside down, the convection
process of heat sink thermal management only keeps the heat sink running hotter. If you must mount an amplifier upside-down, consider adding a fan and do
not run heat inducing loads like 2, 1, or ½ ohm loads. Keep it at 4 ohms and
the amplifier will have fewer thermal problems overall, especially when mounted
upside down.
Another mounting orientation to avoid is mounting amplifiers directly to a subwoofer enclosure. The excessive panel vibration produced by low frequency
information may vibrate critical solder joints on the circuit board loose. Additionally, excessive external vibration can also cause a power supply oscillation.
One general consideration for any amplifier placement is that routinely warm
(even hot) climates often generate temperatures in excess of 130°F in the trunk
area of the vehicle. Most amplifiers have a thermal protection circuit that shuts
the amplifier down at 170-180°F, which is a relatively small range considering
the way some amplifiers are continually required to pound out hours of sound.
CHAPTER 2. ADVANCED INSTALLATION KNOWLEDGE AND TECHNIQUE
371
Margin Notes
Passive crossovers often
contain many types of
inductors to filter or pass
specific frequency ranges.
As current changes (such as in AC applications), the inductive reactance opposes
the change in current flow by the stability of the magnetic field.
Remember, while resistance limits or opposes current flow in a circuit (regardless
of the frequency), inductance opposes a change in current flow. High frequency
signals represent rapidly changing currents. Therefore, inductors can limit the
strength of higher frequency signals, while still allowing lower frequencies to pass.
The larger the inductance value, the more it will oppose changes in current flow.
Where it applies to frequency, larger values of inductance are required to block or
oppose frequency as it drops.
An inductor wired in series with a subwoofer allows the low frequency audio signal
to pass to the speaker but blocks the higher frequency signal. This is an example
of a basic low pass passive crossover. In this case, the AC is the audio output from
an amplifier. More complex passive crossovers like the kind that are included with
mid/tweeter component speakers may have multiple small inductors in them.
Examples of Air Core and Iron Core inductors as well as a ring shaped toroidally
wound iron core inductor.
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THE ADVANCED INSTALLATION TECHNICIAN STUDY GUIDE
Margin Notes
How to easily use Ohm’s Law to figure out an unknown.
Example 1
Suppose you have a single resistor with a measured value of 8 Ohms (R = 8), and
you measure the amount of current that flows through the resistor at 2 amperes
(I = 2). What is the voltage supply in that circuit? Simply apply Ohm’s Law:
To find Voltage, simply cover it up and do the math of the remaining parameters.
Q
Q
Q
Q
Q
Q
Q
R=8
I=2
Cover up the parameter “E” in the Ohm’s Law “T-I-R-E” chart.
What’s left is current and resistance so you’ll multiply those.
E=IxR
E=2x8
E = 16 Volts supplied in that circuit
CHAPTER 1. ADVANCED ELECTRONICS AND VEHICLE ELECTRICAL SYSTEMS
51
Master Installation Technician Study Guide TABLE OF CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
CHAPTER 1: VEHICLE ELECTRICAL SYSTEMS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Advanced Electronic Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Zener Diodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Transistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Current Limitations of Transistors . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Bipolar PNP and NPN Transistors . . . . . . . . . . . . . . . . . . . . . . . . . . 6
JFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
MOSFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Operational Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
ICs in Headunits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Logic Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
The “AND” Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
The “OR” Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
The “NOT” Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
The “NAND” Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
The “NOR” Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
The “XOR” Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
The “XNOR” Gate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Switching Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Data Bus Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Serial Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Electronic Control Units and Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
OBD-II (the most basic of data bus communications) . . . . . . . . . . . . . . . . . . . . 24
OBD Scan and Diagnostic Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
OBD-Compliant Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Overview of Multimedia and Control Networks . . . . . . . . . . . . . . . . . . . . . . . . 29
What is this type of network and why is it there? . . . . . . . . . . . . . 29
In what vehicles or applications are networks found? . . . . . . . . . . 29
What types of network messages are there? . . . . . . . . . . . . . . . . . . 30
How can you identify the network (visually, electrically
and operationally)? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
What areas or OEM components of the vehicle are affected?. . . . . 31
How does this change my installation process or how
does it affect my job? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
What are some things NOT to worry about? . . . . . . . . . . . . . . . . . 32
What are some of the things TO worry about? . . . . . . . . . . . . . . . . 33
What—if anything—is an aftermarket solution or approach? . . . . 34
ANSI/CEA-2012-A Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Hybrid Gas-Electric Vehicle Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
High-Voltage System Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Integrated Starter Alternator (ISA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
TABLE OF CONTENTS
v
Cold-Start Wire (Second Starter). . . . . . . . . . . . . . . . . . . . . . . . . . 264
Key-Sense Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
Tachometer Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Transponder Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Interfacing Advancements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
GM PASSKey 3+ Transponder . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
Programming a Transponder Key . . . . . . . . . . . . . . . . . . . . . . . . . 270
Toyota/Lexus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Ford, Lincoln, Mercury PATS
(1996, 1997, some early 1998 models) . . . . . . . . . . . . . 271
Ford, Lincoln, Mercury PATS (most 1998, 1999 and up) . . . 272
Ford Focus and Escape (2001 and up) . . . . . . . . . . . . . . . . . 272
Mazda Tribute (2001 and up) . . . . . . . . . . . . . . . . . . . . . . . . 272
GM PassKey III (PK3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
GM PassKey III+ (PK3+ on 2001 and up GM vehicles) . . . . 273
Chrysler (Sentry Keys) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Remote-Start Suggestions for Smart Key Applications . . . . . . . . . 274
Remote-Start Integration with
Retained Accessory Power Circuits . . . . . . . . . . . . . . . . . . . . 275
Disarming Factory Security Systems . . . . . . . . . . . . . . . . . . . . . . . 276
Troubleshooting Remote-Starter Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Vehicle Will Not Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
No Lights Flashing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Does Not Crank, But Lights Flash. . . . . . . . . . . . . . . . . . . . . 277
Cranks, But Not Long Enough To Start. . . . . . . . . . . . . . . . . 277
Starts Up and Shuts Down Early . . . . . . . . . . . . . . . . . . . . . . 277
Pre-Bypass Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
Programming or Setting up Bypass Modules . . . . . . . . . . . . . . . . . . . . . . . . . 279
Troubleshooting Factory Hood Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Sample Test Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
CHAPTER 5: IN-VEHICLE INFORMATION SYSTEMS
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
Regulatory Groups and Rules Affecting Mobile CE. . . . . . . . . . . . . . . . . . . . . 285
National Highway Traffic Safety Administration (NHTSA) . . . . . 285
Federal Communications Commission (FCC) . . . . . . . . . . . . . . . 287
Occupational Safety and Health Administration (OSHA) . . . . . . 287
Wireless Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
Bluetooth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
Headset Profile (HP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
Hands-Free Profile (HFP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Advanced Audio Distribution Profile (A2DP) . . . . . . . . . . . . . . . 293
Audio/Video Remote Control Profile (AVRCP) . . . . . . . . . . . . . . . 293
Object Push Profile (OPP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
Phone Book Access Profile (PBAP) . . . . . . . . . . . . . . . . . . . . . . . . 294
WWAN, WiMax, and other Network Access Solutions . . . . . . . . 294
Telematic Systems Using Wireless Communications . . . . . . . . . . 295
Vehicle Infrastructure Integration . . . . . . . . . . . . . . . . . . . . . . . . . 295
TABLE OF CONTENTS
xi
As with all semiconductors, voltage
drop between terminals (also called
“breakdown voltage”) is a design
limitation. Breakdown voltages must
be taken into account for each
combination of terminals (i.e., Vce,
Vbe and Vcb). However, Vce
(collector-emitter voltage) with open
base, designated as Vceo, is usually
of most concern and defines the
maximum circuit voltage. Basically
this is the “unloaded” operation of
the transistor, which should never
happen unless the protection circuit
of a device creates that open circuit
in an effort to save the transistor
from destruction.
Margin Notes
What about the term “Darlington”?
It’s used quite often in mobile
electronics, especially in amplifier
output topologies. Darlington
transistors contain two transistors
connected in an emitter-follower
configuration, while sharing the same collector contact, all within the same
case. This structure can be fabricated with the same technology as a single
bipolar transistor, which means you cannot really tell by just looking at the
outside of the transistor.
■
Figure 7. The water flow analogy for an NPN
transistor demonstrates electron flow (negatively charged particles) moves from emitter
to collector and the rate is determined by the
faucet valve (which is the base).
The key advantage of the
Darlington configuration is that
the total current gain (or beta)
of the circuit equals the product
of the current gain of the two
devices. The disadvantage is the
larger saturation voltage. Since
the two devices share the same
collector, the saturation voltage
of the Darlington pair equals the
forward bias voltage of transistor
Q2 plus the saturation voltage of
transistor Q1. Since the forward
bias voltage is much larger than
the saturation voltage, the saturation voltage of the Darlington
pair is also significantly larger.
This larger voltage results in
larger on-state power dissipation
in the device.
CHAPTER 1. VEHICLE ELECTRICAL SYSTEMS
✍ Beta or H
FE
is the gain of
the transistor
■
Figure 8. A schematic representation of
an NPN Darlington pair. In practice,
this would be in a single transistor
package and look just like other transistors of the same package type but has a
much higher beta.
9
Margin Notes
A serial data stream contains bits that each hold a specific place in the data
stream. Bits can represent a message being sent or even a separation (pause)
between messages. These bits are being sent at precise time intervals. The
speed at which bits are transmitted is known as baud rate. The digital messages are sent one after the other in a single direction. In order for electronic
control module number two to understand the signal from electronic control
module number one, they must be synchronized with an internal clock,
which is based on the prescribed baud rate.
It is also possible for two computers to send and receive on the same conductor (or group of conductors). The very basis of a “network” using control
modules in modern vehicles is multi-tasking electrical signals over a common conductor path. This is often called “multiplexing” in electrical terms,
but the implementation and evolution in vehicle electrical systems has
changed dramatically.
✍ Data messages with arbitration bits allow the more
important message to win if 2
or more messages are transmitted to the same receiving
device at the same time.
“Synchronous” refers to data signals that are constant, meaning the signal
never stops as long as the computers are active. “Asynchronous” refers to
signals that are sent only when necessary, meaning they are NOT constant.
The computer that sends messages includes start and stop codes with the
asynchronous signal so that the computer that receives the data can correctly
interpret the information and understand when the message is finished.
These are often called start of frame (SOF) and end of frame (EOF) identifiers. In data bus systems that transmit asynchronous data, there is usually
another section of the messages that contains a section called “arbitration.”
This means that when two or more messages are sent and arrive at a particular destination at the same time, one must always “win” as a matter of priority.
For instance if an ABS brake signal and an oil level warning signal arrived at
a computer at the same time, the ABS brake signal would take priority.
■
Figure 17a. This is an example of a low resolution
GM Class 2 data bus signal shown on the scope
screen of a diagnostic scan tool.
■ Figure 17b. This is an example
of a low resolution CAN-BUS (2.0B) data
bus signal, both HI and LOW signal
components, shown on the scope screen of a
Fluke 124 oscilloscope. Simultaneously
reading these signals with an oscilloscope
requires a dual input capacity.
20
THE MASTER INSTALLATION TECHNICIAN STUDY GUIDE
SAMPLE TEST QUESTIONS
Margin Notes
In the process of reviewing your knowledge of Chapter 1 subject matter,
please remember that this guide assumes you have mastery of the information presented in the MECP Advanced Installation Technician Study Guide.
If necessary, please review that guide prior to proceeding with sample test
questions.
1. Choose an appropriate substitute for a relay in a low current DC
switching application?
a. A potentiometer.
b. A Silicon Controlled Rectifier (SCR).
c. An NPN transistor.
d. A Zener diode.
2. What is the time constant formula for capacitors?
a. 1 Time Constant = R × C (Resistance times Capacitance).
b. 1 Time Constant = R / C (Resistance divided by Capacitance).
c. 1 Time Constant = C / R (Capacitance divided by Resistance).
d. 1 Time Constant = (C + R)2 (Capacitance plus Resistance squared).
3. What device can be placed on a relay to protect transistorized outputs
on an ECU?
a. Silicon Diode.
b. Carbon Resistor.
c. Iron Core Inductor.
d. Another Relay.
4. How would the device from question 3 above be placed on the relay?
a. In series between the load and terminal 30.
b. In parallel across the coil terminals.
c. In parallel between terminal 30 and 86.
d. In series between the trigger and terminal 85.
5. What is the electrical power consumption of a device with 13.8 volts of
supply and a current draw of 150 milliamps?
a. 0.01 Watts
b. 0.092 Watts
c. 2.07 Watts
d. 10.87 Watts
CHAPTER 1. VEHICLE ELECTRICAL SYSTEMS
57
for high-volume production runs. Many instrument panel manufacturers can
produce surface to color (mold-in color) or finish the instrument panels with
soft touch coatings that are colored in a post-production process.
Margin Notes
Vacuum forming allows consistent production of larger panels in which flexible plastics are used. This is an ideal process for door and side panel parts,
as well as other large dimension interior panels. Such parts create greater
challenges in integrating aftermarket mobile electronics products because of
the type of material used, the color and the texture. All of these points must
be considered in an integration job.
■
Figure 8. Large industrial vacuum forming machines
often make interior panels and dashboards.
Making repairs or modifications to the plastic panels requires identifying the
specific plastic involved. Over the years that has become more and more
challenging. A simple way of looking at OEM plastics is to break them down
into three basic types: flexible, semi-rigid and extra rigid. This further separates thermoplastics and thermosets by the “gray area” of semi-rigid plastics,
which may have attributes of both types. Once you identify which type of
plastic you are working with (or considering modifying), you stand a much
better chance of achieving a “factory-like” result with the adhesion, surfacing
and finishing.
Flexible Plastics (definitely thermoplastics)
■
PUR (polyurethane)
■
TPUR (thermoplastic polyurethane)
Semi-Rigid Plastics (generally thermosets, but may have a thermoplastic
“character”)
■
ABS (acrylontrile butadiene styrene)
■
TPO (thermoplastic olefin)
■
TPE (thermoplastic elastomer)
■
UP (polyester thermoset)
■
EPDM (ethylene propylene diene monomer)
CHAPTER 2. INSTALLATION KNOWLEDGE AND TECHNIQUE
67
Margin Notes
■
Figure 34a.
This is the
setup for the
Hall Effect
current clamp.
A. Prepare the DC current clamp for a measurement. On most clamps,
you will have to “zero out” the display so that your measurement has
the highest probable accuracy.
Note: If you are using a powered accessory clamp (such as the Fluke i410,
i1010 or equivalent), you will plug into the volt/ohm and COM jacks
on your DMM and set the meter to the DC millivolt (mV) setting. The
clamp has an internal battery that converts high current into a safe, lowvoltage signal that the meter will safely display. In the case of the Fluke
i410 or i1010 clamp, 1mV on the DMM display = 1a of current flow
measured through the clamp.
B. Clamp the meter around the positive cable connecting the alternator
to the battery. Make sure no other wiring is inside the clamp jaw
because this will skew the measurement. You may see an arrow on the
clamp jaws. This is a current flow indicator. It should point toward the
alternator.
■
Figure 34b. Step 8 is a reference charging current measurement with no accessory loads
done at 2000 RPM. Remember
1mV on the meter equals 1A
measured at the Hall Effect
Clamp jaw.
C. With hands and test leads clear of any obstructions, start the motor.
D. All accessories should be off.
E. Advance engine speed to 2000 rpm.
F. Read and record the DC current measurement. If your measurement
reads out in negative numbers (e.g., “–22” instead of “22”), you simply
have the clamp placed backward on the wire. Reverse it if you wish to
confirm the measurement.
Note: Record the highest measurement you see, but leaving the “MAX”
function off allows you to see how frequently that measurement holds. This
is because the loads on the alternator are dynamic.
Current: No Load, No Accessories, Car RUNNING (2000 rpm) ___________
Step 9
Perform a loaded current measurement on the charging system at 2000 rpm.
You will load up the electrical system again to see how the charging system
handles the load with the same accessory loads as in previous measurements.
CHAPTER 2. INSTALLATION KNOWLEDGE AND TECHNIQUE
89
SAMPLE TEST QUESTIONS
Margin Notes
In the process of reviewing your knowledge of Chapter 2 subject matter,
please remember that this guide assumes you have mastery of the information presented in the MECP Advanced Installation Technician Study Guide as
well as a minimum of three years of hands-on professional experience.
1. Which direction does the bit move in a router table setup?
a. Clockwise
b. Counter-clockwise
c. It oscillates vertically
d. It oscillates left to right
2. What is the shielding gas used for MIG welding carbon steel?
a. 100% Carbon Dioxide
b. 75% Carbon Dioxide and 25% Argon
c. 75% Argon and 25% Carbon Dioxide
d. 100% Argon Carbon Dioxide
3. What is the threshold for AC ripple measurements to cause concern for
engine noise issues?
a. 0.3 volts
b. 3 volts
c. 12.66 volts
d. 13.8 volts
4. Which one of the devices listed measures DC current over 10 amperes?
a. Incandescent Test Light
b. OBD-II Scan Tool
c. Inductive Clamp
d. Hall Effect Clamp
5. When spraying professional grade upholstery adhesives from an HVLP
gun, what is the minimum recommended ambient temperature?
a. 40 degrees F / 4 degrees C
b. 50 degrees F / 10 degrees C
c. 65 degrees F / 18.3 degrees C
d. 72 degrees F / 22.22 degrees C
CHAPTER 2. INSTALLATION KNOWLEDGE AND TECHNIQUE
143
Margin Notes
■
Figure 38. Adhesive sheet damping materials on the inside skin and outer skin are important
for controlling any unwanted resonances.
that the speaker fires parallel to the windshield and is located as close to it as
possible, then reflections can be minimized or eliminated.
Some reflections in a car will be unavoidable. No car audio system will ever
be able to control all reflected energy because reflected energy is what human
hearing systems cue on to determine the sense of space in which we are listening. Therefore, it’s a good idea to experiment with controlling reflections
that occur close to the speakers—or close to our ears—that can have negative effects on the overall soundstage, imaging and frequency response.
A good technique for controlling reflections off of surfaces like the side
windows and windshield is to attenuate the energy from the speaker acoustically pointed toward that surface before it can reach the offending reflective
surface. For example, the direct sound from the speaker is the desired sound,
the sound you want. If the speakers in the right kick panel have a direct path
to the listener’s right ear, that is good. However, if the sound from the right
speakers can also travel directly to the left side window, and be reflected back
to the listener, that can cause problems. Since it is not possible to place
absorptive material on the left side window, why not place foam material
between the right side speaker and the left side window? Place the foam so
that it does not affect the direct path to the listener, but does attenuate the
path toward the left side window.
Another technique for controlling reflections is to re-orient panels in the
vehicle to direct reflected energy to areas where it will not affect the desired
sound. An example might be a reflection off of the center console from the
kick panel-mounted speakers. The console panels could be reconstructed so
that the reflection is directed elsewhere, preferably into an absorptive panel.
An absorptive material’s effectiveness at controlling a reflection depends on
its density, surface type and thickness. The lower the frequency of the reflec-
CHAPTER 3. MOBILE A/V SYSTEMS
201
Margin Notes
AUX-IN via OEM Integration Device
Many of the latest OEM integration devices that are intended to allow adding
an aftermarket amplifier on to the OEM headunit offer one or more auxiliary
inputs. This is an excellent option for sound quality and to gain the benefits
of that particular device, whether it is equalization, signal buffering or something else. However, the drawback is that there must be an external volume
control to be able to vary the signal so it can closely match the signal levels
of the OEM system inputs. This can be the volume control on the carry-in
device itself, or a separately installed volume knob elsewhere in reach of the
user. Typically in this scenario, the user would set the level of the connected
portable device(s) as well as the OEM headunit, and use a single volume
control for the volume function on all the sources.
CUSTOM MODIFICATIONS
Although this is an alternative handled on a case-bycase basis depending on the
vehicle year/make/model
and trim level, there are
instances where custom
modifications can allow
“clean” preamp-level aux
input into an OEM headunit. These modifications
are not at all intended to be
completed in most shops,
but rather by experienced
bench technicians with the
ability to disassemble,
examine and test these
units out of the vehicle.
✍ OEM Amplifiers sometimes
perform master volume,
balance, and fader functions
even though it is initiated from
the headunit.
■
Figure 46. Circuit board level aux input modifications
like this BMW 7 Series weather band tuner input are
reserved for only the most skilled technicians and are not
practical for everyday install shops.
Some vehicles can simply use a changer cable that is interrupted via solidstate switching to allow input as if the audio were coming from a changer,
but still maintain the changer communication loop. Other, more intense
modifications take place inside the unit, which may reside in the dash or
even in a hidden location for a tuner or factory amplifier. The modification
usually involves using an audio source input that already exists (such as the
weather band tuner in BMWs) and making modifications. That gives the
installation technician a set of full-range, preamp-level analog inputs. Again,
this is a case-by-case basis and is the audio equivalent of the “engine tuners”
modifying ECUs in modern street-racing cars.
ADDING A HEADUNIT TO AN OEM AMPLIFIER
Exchanging headunits can be difficult without the use of adapters. While
this is the ultimate source input (changing the entire source unit), issues
must be addressed with regard to the audio-input differences between what
the aftermarket source unit offers and what the OEM amplifier will accept.
226
THE MASTER INSTALLATION TECHNICIAN STUDY GUIDE
SAMPLE TEST QUESTIONS
Margin Notes
In the process of reviewing your knowledge of Chapter 3 subject matter,
please remember that this guide assumes you have mastery of the information presented in the MECP Advanced Installation Technician Study Guide as
well as three years of hands-on professional experience installing mobile
audio and video systems including designing systems and troubleshooting
installation related issues.
1. How much power does 40 volts of output into 4-Ohms on a single
amplifier channel produce?
a. 10 Watts
b. 160 Watts
c. 400 Watts
d. 6400 Watts
2. Asymmetrical crossover points are described as?
a. Crossover points sharing the same cut off frequency.
b. Crossover points sharing different cutoff frequencies.
c. Crossover points beyond 24dB/Octave slope.
d. A crossover that is either HP or LP designated by a switch.
3. When the size of a vented enclosure decreases and the vent area stays
constant, which is true of vent length?
a. It must be longer to maintain the same tuned frequency.
b. It must be shorter to maintain the same tuned frequency.
c. If it remains the same length, so will the tuned frequency.
d. Vent length is dependent on the subwoofer not the enclosure volume.
4. What is the default file format of iTunes music management software for
the iPod?
a. AAC
b. MP3
c. WAV
d. WMA
5. In audible terms, which of the following statements is correct?
a. White noise has more audible low frequency than pink noise.
b. Pink noise has more audible low frequency than white noise.
c. Pink noise and white noise have identical audible low
frequency content.
d. Neither pink noise nor white noise has any audible low
frequency content.
CHAPTER 3. MOBILE A/V SYSTEMS
255