Ignition System: Testing and Inspection

CIRCUIT DESCRIPTION
The ignition control module (ICM) has independent power and ground circuits. The circuits between the ICM and the powertrain control module (PCM) consist of the following circuits:
- The IC timing signal
- The IC timing control
- The low-resolution engine speed signal
- A low reference signal

The ICM sends 3X signals to the PCM. The ICM controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions:
- The PCM receives the second 3X signal.
- The PCM applies 5 volts to the IC timing signal circuit.

DIAGNOSTIC AIDS
- An arcing spark plug wire or an arcing ignition coil to the ICM may cause a stall, misfire or a no start condition.
- The following may cause a no start condition:
- Crankshaft reluctor wheel damage or improper installation
- The CKP sensor coming in contact with the reluctor wheel
- Foreign material passing between the CKP sensor and the reluctor wheel
- Excess crankshaft end play will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in any of the following conditions:
- A no start
- A start and stall
- Erratic performance
- An improperly installed crankshaft could cause excess crankshaft end play.

TEST

Steps 1-4:

Steps 5-9:

Steps 10-14:

Steps 15-19:

Steps 20-23:

Steps 24-29:

Steps 30-32: