TPS/RPM Activated Switch
PN 8940
Parts Included:
1 - TPS/RPM Switch
1 - Parts Bag
WARNING: Before installing the TPS/RPM Activated Switch disconnect the battery cables. When
disconnecting the battery cables, always remove the Negative (-) cable first and install
it last.
The MSD TPS/RPM Activated Switch allows the user to easily set an engine rpm and Throttle Position
Sensor (TPS) setting to activate (and deactivate) a circuit. Primary use will be on nitrous applications,
but it could also be used for alcohol injection or other circuits. The Switch can be used with traditional
3-wire TPS switches or throttle-by-wire systems on engines with 4, 6 or 8-cylinders.
Operation
The Switch will provide 12 volts to activate a circuit and will handle up to 20 amps for 20 seconds
continuous. A circuit will be activated only when all of the following programmable criteria are met:
•The TPS setting is above the preset voltage.
•The rpm is above the minimum preset rpm.
•The rpm is below the maximum preset rpm.
•The launch disable input is off.
WIRING
RED
On/Off Switch. Connect to a switched 12 volts that can supply up to 20 amps.
BLACK
Ground. Connect to the TPS ground or to the engine ground.
WHITE
RPM Signal. Connect to a coil negative or injector reference signal wire.
TAN
Throttle Signal. Connects to the 5 volt signal wire of a 3-wire TPS or to a throttle pedal
sensor. Also operates with 12 volts through a microswitch. Note that at wide open
throttle, there must be more than 2.5 volts on the signal wire to use this switch.
YELLOW
Activation Wire. Connects to the solenoid being activated. Can drive up to 20 amps
for 20 seconds continuous.
BLUE
Launch Disable. When connected to 12 volts through the clutch switch or trans brake,
the Switch will be deactivated. This wire overrides all other activation wiring.
MSD
IGNITION
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INSTALLATION INSTRUCTIONS
NITROUS
RELAY
OUTPUT
BLUE
YELLOW
WHITE
BLACK
TAN
TPS
RED
DISABLE
CLUTCH/TRANSBRAKE
12 VOLTS
TPS
SIGNAL
5V
NITROUS
SOLENOIDS GROUND
GROUND
SWITCHED
12V
RPM SIGNAL
TO TACH OUTPUT
COIL NEGATIVE (-)
INJECTOR SIGNAL
Figure 1 Typical Wiring of the TPS/RPM Activated Switch.
PROGRAMMING
There are four buttons to set the Switch. There is also an LED that will assist in setting up and verifying
your settings. To measure the TPS voltage, probe the TPS signal wire with a DVOM, or, on late model
vehicles, having an OBD scanner will be helpful.
Setting the TPS Activation Points
1. Turn ignition switch to the On position.
2. Press the throttle pedal to the desired activation point (typically wide open throttle).
3. Press and hold the Set button.
4. Press the TPS button. The LED will turn On alerting the new setting was recorded.
Note: TPS must be above 2.5 Volts to be recorded.
5. Release the Set and TPS buttons.
Setting the On RPM Activation Point
1.
2.
3.
4.
5.
Start the engine.
Raise the engine rpm to HALF of the desired activation rpm and hold it.
Press and hold the Set button.
Press the RPM On button. The LED will turn ON alerting the new setting was recorded.
Release the SET and RPM ON buttons.
CAUTION: Whenever the On RPM is adjusted, the Off RPM MUST be reset! There will be no Off
RPM unless it is reset each time the On RPM is changed.
MSD
IGNITION
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INSTALLATION INSTRUCTIONS
RPM OFF SETTING
1. With the engine running, raise the rpm to HALF of the desired deactivation rpm point. Note that
this setting should be less than the ignition or fuel limiter.
2. Press and hold the Set button.
3. Press the RPM Off button. The LED will turn On alerting the new setting was recorded.
4. Release the SET and RPM OFF buttons.
Verify TPS and RPM Settings
The LED of the TPS/RPM Switch allows you to verify your settings.
VERIFYING TPS SETTING
1. Turn ignition On.
2. Press and hold TPS button.
3. Press the throttle pedal until the LED turns On. This is the activation setting that is programmed
in the switch.
4. The LED will turn Off when the pedal is moved below this setting.
VERIFYING RPM ON AND RPM OFF SETTINGS
1.
2.
3.
4.
Start the engine.
Press and hold the RPM On or the RPM Off button.
Slowly raise the engine rpm until LED turns On (this will be ½ the activation rpm).
Continue raising the rpm until the LED turns Off (this will be ½ the deactivation rpm).
Note: The LED will stay On when the rpm is within the activation window. It will turn Off when the
rpm reaches the deactivation setting.
TECH NOTES
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MSD
IGNITION
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TECH NOTES
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Service
In case of malfunction, this MSD component will be repaired free of charge according to the terms of the warranty.
When returning MSD components for warranty service, Proof of Purchase must be supplied for verification. After
the warranty period has expired, repair service is based on a minimum and maximum fee.
All returns must have a Return Material Authorization (RMA) number issued to them before
being returned. To obtain an RMA number please contact MSD Customer Service at 1 (888) MSD-7859 or
visit our website at www.msdignition.com/rma to automatically obtain a number and shipping information.
When returning the unit for repair, leave all wires at the length in which you have them installed. Be sure to include
a detailed account of any problems experienced, and what components and accessories are installed on the vehicle.
The repaired unit will be returned as soon as possible using Ground shipping methods (ground shipping is covered
by warranty). For more information, call MSD Ignition at (915) 855-7123. MSD technicians are available from 7:00
a.m. to 6:00 p.m. Monday - Friday (mountain time).
Limited Warranty
MSD IGNITION warrants this product to be free from defects in material and workmanship under its intended normal
use*, when properly installed and purchased from an authorized MSD dealer, for a period of one year from the date
of the original purchase. This warranty is void for any products purchased through auction websites. If found to be
defective as mentioned above, it will be repaired or replaced at the option of MSD Ignition. Any item that is covered
under this warranty will be returned free of charge using Ground shipping methods.
This shall constitute the sole remedy of the purchaser and the sole liability of MSD Ignition. To the extent permitted
by law, the foregoing is exclusive and in lieu of all other warranties or representation whether expressed or implied,
including any implied warranty of merchantability or fitness. In no event shall MSD Ignition or its suppliers be liable
for special or consequential damages.
*Intended normal use means that this item is being used as was originally intended and for the original application
as sold by MSD Ignition. Any modifications to this item or if it is used on an application other than what MSD Ignition
markets the product, the warranty will be void. It is the sole responsibility of the customer to determine that this item
will work for the application they are intending. MSD Ignition will accept no liability for custom applications.
MSD
IGNITION
• w w w . m s d i g n i t i o n . c o m • ( 9 1 5 ) 8 5 7 - 5 2 0 0 • FA X ( 9 1 5 ) 8 5 7 - 3 3 4 4
© 2007 Autotronic Controls Corporation
FRM28883
Created 08/07
Printed in U.S.A.