System Description
This system includes the Distributor, the ignition coil, the ignition control module, the secondary wires, spark plugs, the VCM and the crank sensor. The ignition system is controlled by the Vehicle Control Module (VCM). The VCM monitors the information from various engine sensors, computes the desired spark timing and controls the dwell and firing of the ignition coil via an (IC) line to the ignition control module..
Diagnostic Aids
Check the following items:
| • | Basic engine mechanical problems: |
| - | Distributor drive gear |
| - | Camshaft |
| - | Timing chain and gears |
| • | An intermittent that may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside of the insulation. Check for poor connections or a damaged harness. |
| • | Inspect the VCM harness and the connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection. |
Test Description
The numbers below refer to the step numbers in the diagnostic table.
The battery should be fully charged prior to any tests.
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Perform the OBD system check before proceeding unless it was already performed.
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Checks for proper output from the enhanced ignition system. The spark tester requires a minimum of 25,000 volts to operate. This check can be used in case of an ignition miss, because the system may provide enough voltage to run the engine but not enough to operate a spark plug under heavy load.
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This test separates the distributor cap, rotor, and ignition wires from the ignition coil in order to help identify a secondary ignition system problem.
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This step determines the proper available voltage exists in the primary ignition circuit. This also checks the ignition coil and wiring.
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This test checks the ignition control module, connections and wiring.
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This check begins to determine if the VCM is providing a signal to the ignition control module. If the VCM is not providing a signal to the ignition control module, the problem exists between the ignition control module and the VCM.
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This test checks for a basic engine mechanical problem.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Important: Before clearing the DTCs, use the scan tool to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||||||||||
Is adequate spark present? | -- | Go to Hard Start | ||||||||||
Is adequate spark present? | -- | |||||||||||
4 | Check the coil wire resistance using a DMMJ 39200 , the resistance should be approximately the specified value. Is the resistance within the specified value? | 1000 ohms/inch | ||||||||||
Does the voltage measure above the specified value? | 10.0V | |||||||||||
6 | With a DMM J 39200 , check voltage on terminal D of the ignition control module connector to a ground . Does the voltage measure above the specified value? | 10.0V | ||||||||||
With test light to B+, probe the ignition control module connector terminal C. Is the test light ON? | -- | |||||||||||
8 |
Does the test light FLASH? | -- | ||||||||||
9 |
Does the voltage measure above the specified value? | 10.0V | ||||||||||
10 |
Is the circuit open? | -- | ||||||||||
11 | With a test lamp to B+, probe the ignition coil connector terminal C. Is the test light ON? | -- | ||||||||||
12 | With a test light to B+ probe the ignition coil connector terminal B. Is the test light ON? | -- | ||||||||||
Is the voltage between the specified values? | 1.0-4.0V | |||||||||||
14 |
Are any of these conditions present? | -- | ||||||||||
With the distributor cap removed, crack the engine and check for rotation of the distributor rotor. Does the distributor rotor turn? | -- | Go to Symptoms | ||||||||||
16 |
Is the circuit open? | -- | ||||||||||
17 | With a test light to B+ probe the VCM C3 harness connector pin 9 for the ignition Control (IC) circuit. Is the light ON? | -- | ||||||||||
18 |
Is the test light ON? | -- | ||||||||||
19 |
Check for a faulty ignition feed circuit to terminal A of the ignition control module. Was a problem found? | -- | -- | |||||||||
20 | Check for a faulty ignition feed circuit to terminal A of the ignition coil. Was a problem found? | -- | -- | |||||||||
21 | Check for a faulty ignition control module connection. Was a problem found? | -- | ||||||||||
22 | Check for a faulty ignition coil connection. Was a problem found? | -- | ||||||||||
23 | Check for faulty VCM connection. Was a problem found? | -- | ||||||||||
24 | Repair open ignition control module ground circuit. Refer to Wiring Repairs in Repair Instructions. Is the action complete? | -- | -- | |||||||||
25 | Repair the open IC circuit between the VCM and ignition control module. Refer to Wiring Repairs in Repair Instructions. Is the action complete? | -- | -- | |||||||||
26 | Repair grounded IC circuit between the VCM and ignition control module. Refer to Wiring Repairs in Repair Instruction. Is the action complete? | -- | -- | |||||||||
27 | Repair short to voltage in the IC circuit between the VCM and the ignition control module. Refer toWiring Repairs in Repair Instructions. Is the action complete? | -- | -- | |||||||||
28 | Repair open tachometer signal circuit between the ignition coil and the ignition control module. Refer to Wiring Repairs in Repair Instructions. Is the action complete? | -- | -- | |||||||||
29 | Repair grounded tachometer signal circuit between the ignition coil and the ignition control module. Refer to Wiring Repairs in Repair Instructions. Is the action complete? | -- | -- | |||||||||
30 | Repair grounded tachometer signal circuit between the ignition coil and the instrument cluster. Refer to Wiring Repairs in Repair Instructions. Is the action complete? | -- | -- | |||||||||
31 | Repair the circuit as necessary. Refer to Wiring Repairs in Repair Instructions. Is the action complete? | -- | -- | |||||||||
32 | Replace the ignition coil. Refer to Ignition Coil and ICM Replacement in Engine Electrical. Is the action complete? | -- | -- | |||||||||
33 | Replace the coil wire. Is the action complete? | -- | -- | |||||||||
34 | Replace the distributor rotor. Is the action complete? | -- | -- | |||||||||
35 | Replace the distributor cap. Is the action complete? | -- | -- | |||||||||
36 | Replace the ignition control module. Refer to Ignition Coil and ICM Replacement in Engine Electrical. Is the action complete? | -- | -- | |||||||||
37 |
Is the action complete? | -- | -- | |||||||||
38 | Operate vehicle within the conditions under which the original symptom was noted. Does the system now operate properly? | -- | System OK |
