2A-30 - ELECTRICAL 90-830234R3 DECEMBER 1997
CDM Trouble Shooting Flowchart
Chart #3 (At least one CDM has spark)
Step
Action Value Yes No Tools
1
Resistance Check ALL CDMs Refer to chart Step 3 Replace any
CDMs that
do not pass
specifica-
tions even if
they fire
Step 2
DVA/Multimeter
P/N 91-99750
2
Test all CDMs at Cranking with
Spark Gap Tester
Spark on All CDMs
Will spark jump a 7/16 in.
(11.11 mm) gap?
7/16 in.
(11.11 mm)
gap
Run Engine
Verify Repair
Step 6
Step 3 Spark Gap Tes-
ter
P/N 91-850439
3
Check Trigger Output:
Cranking with CDM disconnected.
Cranking with CDM connected.
1 Volt and
above - CDM
disconnected.
0.2 - 5 Volts -
CDM
connected.
Step 5 2, 3, & 4 Cyl
- Replace
Trigger
Run Engine
Verify Repair
Step 6
6 Cyl–Step 4
DVA/Multimeter
P/N 91-99750
TPI/CDM Test
Harness
84-825207A2
4 V6 Models
Resistance Check Crank Position
Sensor
900 - 1300
Ohms
Step 5 Replace
Crank Posi-
tion Sensor
Run Engine
Verify Repair
Step 6
DVA/Multimeter
P/N 91-99750
5
Test all CDMs at Cranking with
Spark Gap Tester
Spark on All CDMs?
Will spark jump a 7/16 in.
(11.11 mm) gap?
7/16 in.
(11.11 mm)
gap
Run Engine
Verify Repair
Step 6
Replace any
non-firing
CDMs
Step 6
Spark Gap Tes-
ter
P/N 91-850439
6
If mis-firing is in a repeatable
range:
Perform DVA readings on stator
and trigger at all running speeds.*
Stator:
200 Volts and
above
Trigger:
2 Volts and
above
Run Engine
Verify Repair
END
Refer to
*Note Below.
DVA/Multimeter
P/N 91-99750
TPI/CDM Test
Harness
84-825207A2
* Note: Stator tests will only isolate problem down to
a charging pair. Further testing is necessary to deter-
mine faulty CDM. Disconnecting one CDM of the
charging pair is recommended.
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