Point type Ignition Flow Chart
Auto 2
Trouble Shooting
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Fixing something that is broken


How can you fix something efficiently if you
don’t even know how it is broken?
To troubleshoot something that doesn’t work
correctly you need:
– To know how it is suppose to work
– The basics of how it works
– Critical thinking comparing what isn’t working to how
it is suppose to work
– A logical process to eliminate the possible causes of the
problem
– Proper tools
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Trouble shooting

If you had never seen an apple, never read
about an apple, and no one had ever told
you anything about an apple, it would very
difficult for you to tell me what is wrong
with these apples.
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Trouble shooting

It would even be more difficult for you to
tell me how to fix what is wrong with these
apples
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Trouble shooting for no spark
In the same way, if you haven’t learned how we
make spark in the ignition system, it will be
very difficult for you to figure out why an
engine doesn’t have spark
 If you don’t know the basics of electricity, it
will be very difficult for you to diagnose what is
wrong
 If you don’t know how to use test equipment, it
will be very difficult for you to find your
problem

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Logical testing & elimination

Hopefully you learned by now:
– How the primary ignition system works to
make spark
– Basic rules to series and parallel circuits and
can apply the knowledge
– How to select the proper electrical measuring
tools and how to use them

So now we need to learn how to use a
process of elimination to diagnose a vehicle
that doesn’t have spark
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There is usually more that one
right way to fix something

The flow chart I have made for point type
ignition is just the way that is logical and
works efficiently for me
– By no means is it the only way

Since we don’t have a lot of experience yet
with diagnosis, lets use my method for
logically eliminating all the causes of an
ignition system that is not working correctly
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Primary Ignition

We had better know by
now:
– Key on, points on,
primary current flows
and creates a magnetic
field around primary
winding of coil
– Points open, magnetic
field crashes inducing
high voltage into
secondary winding
creating spark
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Draw primary ignition on back of
flow chart fairly large
RUN
-
+
+
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-
10
Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
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Using remote starter to crank
B+
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S
12
Make sure you are checking at the proper end of wire
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Primary ignition circuit
RUN
-
+
+
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-
14
Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
NO
With key on, Is
There power to “+”
Side of coil?
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Primary ignition circuit
RUN
-
+
+
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16
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Making sure test light works
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Points open
Points closed
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Primary ignition circuit
RUN
-
+
+
-
If we didn’t have power to “+” side
of coil, what would be the causes?
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20
Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
NO
With key on, Is
There power to “+”
Side of coil?
NO
Ballast resistor,
wiring to “+”
side of coil or
ign switch is open
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Primary ignition circuit
RUN
-
+
+
If you have power to coil positive
Then you know this side of circuit
Is doing it’s job and we can move
on
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-
What should we
Check next ?
22
Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
NO
With key on, Is
There power to “+”
Side of coil?
YES
NO
Is there power to the
“-” side of coil key on?
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Ballast resistor,
wiring to “+”
side of coil or
ign switch is open
23
Primary ignition circuit
RUN
-
+
+
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-
24
Must have primary wires for coil hooked up
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Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
NO
With key on, Is
There power to “+”
Side of coil?
YES
NO
Is there power to the
“-” side of coil key on?
NO
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Ballast resistor,
wiring to “+”
side of coil or
ign switch is open
Crank engine, does test
light blink on “-” side
of coil
26
Primary ignition circuit
RUN
-
+
+
-
When we crank the engine
What should the points do?
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Must have primary wires for coil hooked up
CRANK
CRANK CRANK CRANK CRANK
CRANK
CRANK CRANK
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Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
NO
With key on, Is
There power to “+”
Side of coil?
YES
NO
Is there power to the
“-” side of coil key on?
STAYS OFF
(NO VOLTAGE)
NO
Ballast resistor,
wiring to “+”
side of coil or
ign switch is open
Crank engine, does test
light blink on “-” side
of coil
NO
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Primary ignition circuit
RUN
-
+
+
-
So while cranking the engine
The light stays off
How much voltage should be left on the “-” side of
Coil with the points closed and current flowing?
How much voltage should be on the “-” side of
Coil with the points open?
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Write on back of flow chart

With voltage to “+” side of coil, there are
only four things that will cause no voltage
to “-” side of coil while cranking (light stays off)
1. Points always closed
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Primary ignition circuit
RUN
-
+
+
-
What else would cause
The light to stay off?
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Write on back of flow chart

With voltage to “+” side of coil there are
only four things that will cause no voltage
to “-” side of coil while cranking (light stays off)
1. Points always closed
2. Open or grounded primary winding in coil
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Open Primary winding
Don’t forget to isolate one side of the coil
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Primary ignition circuit
RUN
-
+
+
-
What else would cause
The light to stay off?
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Write on back of flow chart

With voltage to “+” side of coil there are
only four things that will cause no voltage
to “-” side of coil while cranking (light stays off)
1. Points always closed
2. Open or grounded primary winding in coil
3. Grounded condenser
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Grounded condenser
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Checking a good condenser
It will
charge
up and go
to infinite
resistance.
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Write on back of flow chart

With voltage to “+” side of coil there are
only four things that will cause no voltage
to “-” side of coil while cranking (light stays off)
1. Points always closed
2. Open or grounded primary winding in coil
3. Grounded condenser
4. Grounded wire between coil “-” and points
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Shorted primary wire to ground
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Checking Conventional Ignition Systems
Is there spark
while cranking?
NO
With key on, Is
There power to “+”
Side of coil?
YES
NO
Is there power to the
“-” side of coil key on?
Let’s continue on
NO
Ballast resistor,
wiring to “+”
side of coil or
ign switch is open
Crank engine, does test
light blink on “-” side
of coil
NO
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Crank engine, does test
light blink on “-” side
of coil
NO
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Crank engine, does test
light blink on “-” side
of coil
NO
Are points always staying closed? LOOK
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Crank engine, does test
light blink on “-” side
of coil
NO
Are points always staying closed? LOOK
YES
NO
Adjust Dwell
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Do coil test
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Crank engine, does test
light blink on “-” side
of coil
NO
Are points always staying closed? LOOK
YES
NO
Adjust Dwell
Do coil test
GOOD
BAD
Check for a
grounded condenser
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Replace
45
Crank engine, does test
light blink on “-” side
of coil
NO
Are points always staying closed? LOOK
YES
NO
Adjust Dwell
Do coil test
GOOD
BAD
Check for a
grounded condenser
GOOD
BAD
Replace
Replace
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Primary wire between
“-” side of coil and
points is grounded Repair
46
That takes care of
The staying off side
Crank engine, does test
light blink on “-” side
of coil
NO
#1
Are points always staying closed? LOOK
YES
NO
#2
Adjust Dwell
#3
Do coil test
GOOD
BAD
Check for a
grounded condenser
GOOD
BAD
Replace
Replace
#4
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Primary wire between
“-” side of coil and
points is grounded Repair
47
Crank engine, does test
light blink on “-” side
of coil
NO
Are points always staying closed? LOOK
YES
NO
Adjust Dwell
Do coil test
GOOD
BAD
Check for a
grounded condenser
GOOD
BAD
Replace
Replace
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Primary wire between
“-” side of coil and
points is grounded Repair
48
Checking Conventional Ignition Systems
Is there spark
while cranking?
NO
With key on, Is
There power to “+”
Side of coil?
YES
NO
Is there power to the
“-” side of coil key on?
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Ballast resistor,
wiring to “+”
side of coil or
ign switch is open
49
Primary ignition
circuit
Is there power to the
“-” side of coil key on?
RUN
-
+
+
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50
Is there power to the
“-” side of coil key on?
YES
Crank engine: does
Test light blink on
“-” side of coil?
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Primary ignition circuit
RUN
-
+
+
-
When we crank the engine
What should the points do?
11/2001
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Primary ignition circuit
RUN
-
+
+
-
So while cranking the engine
The light stays on
How much voltage should be left on the “-” side of
Coil with the points closed and current flowing?
How much voltage should be on the “-” side of
Coil with the points open?
11/2001
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Write on back of flow chart

There are only three things that will cause
voltage all the time to “-” side of coil while
cranking (light stays on)
1. Points always open
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Point always open
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Primary ignition circuit
RUN
-
+
+
-
What Else would
Cause the light
To say on ?
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Write on back of flow chart

There are only three things that will cause
voltage all the time to “-” side of coil while
cranking (light stays on)
1. Points always open
2. Open primary wire between “-” coil and points
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Open primary wire
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Primary ignition circuit
RUN
-
+
+
-
What Else would
Cause the light
To say on ?
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59
Write on back of flow chart

There are only three things that will cause
voltage all the time to “-” side of coil while
cranking (light stays on)
1. Points always open
2. Open primary wire between “-” coil and points
3. Points not grounded or contacts bad
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Points not grounded
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Is there power to the
“-” side of coil key on?
YES
Crank engine: does
Test light blink on
“-” side of coil?
NO
Are points
always open?
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Is there power to the
“-” side of coil key on?
YES
Crank engine: does
Test light blink on
“-” side of coil?
NO
Are points
always open?
NO
Points are either not grounded
or primary wire is open between
“-” side of coil and points
Check & repair
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If the light blinks
while cranking. .
GREAT
It has to blink
To have spark
Is there power to the
“-” side of coil key on?
YES
Crank engine: does
Test light blink on
“-” side of coil?
YES
NO
Are points
always open?
Adjust dwell to Specs
YES
NO
Points are either not grounded
or primary wire is open between
“-” side of coil and points
Check & repair
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If the light blinks
and the dwell is
set correctly
Is there power to the
“-” side of coil key on?
YES
Crank engine: does
Test light blink on
“-” side of coil?
YES
NO
Are points
always open?
Adjust dwell to Specs
Is there spark?
YES
GREAT If vehicle
won’t start, restart
at11/2001
top of flow chart
VHS Auto
YES
NO
Points are either not grounded
or primary wire is open between
“-” side of coil and points
Check & repair
65
If still no spark
Is there power to the
“-” side of coil key on?
YES
Crank engine: does
Test light blink on
“-” side of coil?
YES
NO
Are points
always open?
Adjust dwell to Specs
Is there spark?
YES
NO
Points are either not grounded
or primary wire is open between
YES
NO
“-” side of coil and points
Check & repair
GREAT If vehicle
Test coil & coil wire
won’t start, restart
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at11/2001
top of flow chart
Checking Coil Wire
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Open Secondary Winding
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Open coil wire
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Is there power to the
“-” side of coil key on?
YES
Crank engine: does
Test light blink on
“-” side of coil?
YES
NO
Are points
always open?
Adjust dwell to Specs
Is there spark?
YES
NO
Points are either not grounded
or primary wire is open between
YES
NO
“-” side of coil and points
Check & repair
GREAT If vehicle
Test coil & coil wire
won’t start, restart
GOOD
BAD
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at11/2001
top of flow chart
Condenser is either open
Replace
or not grounded Repair
Checking a good condenser
It will
charge
up and go
to infinite
resistance.
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Open condenser
It won’t
charge up.
Always at
infinite
resistance.
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Condenser not hooked to ground
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Weak Spark



Point type ignition should produce at least 20,000
volts (20 KV) which should jump up to at least ¼”
and be blue in color
Let’s write this up at the to right of flow chart
Weak spark can be caused by:
–
–
–
–
Dwell out of specs
Bad coil (shorted windings, secondary open)
Bad condenser
Pitted points that arc
NEW
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PITTED
74
We should be able to succeed
Next time we are in the shop, you will have
50 minutes to diagnosis and repair a vehicle
that the customer complains of a “NO START”
 It will have at least one problem in the
primary ignition system that causes no
spark
 You will also be responsible to make sure
the dwell is set correctly before you give it
back to the customer

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Questions?
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Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
YES
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Spark at coil wire
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Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
YES
Fuel system must
be in order
Is there spark at
one or two plug wires?
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Spark at plug wire
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Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
YES
Fuel system must
be in order
Is there spark at
one or two plug wires?
NO
Repair bad
cap or rotor
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Bad cap and bad rotor
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Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
YES
Fuel system must
be in order
Is there spark at
one or two plug wires?
NO
YES
Make sure firing
order is correct
Is distributor
in time?
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Repair bad
cap or rotor
83
Firing order and distributor in time

Firing Order
– Have to know which way distributor rotates
– Have to know firing order
– Have to know where #1 plug it

Distributor in time
– Remove #1 plug and start up on compression
stroke
– Turn by hand (less than ½ turn) to TDC
– See if rotor is point to #1 on cap
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Firing order
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Checking Conventional Ignition Systems
Is there spark from coil
wire while cranking?
YES
Fuel system must
be in order
Is there spark at
one or two plug wires?
NO
YES
Make sure firing
order is correct
Is distributor
in time?
YES
NO
Repair bad
cap or rotor
Correct
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If still have spark butVHS
won’t
start, check for
Auto
mechanical problems (compression)
86
Congratulations

Once we learn fuel systems, you should be
able to efficiently diagnosis why a car with
point type ignition won’t start
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Questions?
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