Electronic Ignition (EI) System Diagnosis

CIRCUIT DESCRIPTION
The ignition control (IC) module has independent power and ground circuits. The circuits between the IC module and the powertrain control module (PCM) consist of the following:
^ The low reference circuit
^ The low resolution engine speed signal
^ The two IC timing control signals
- For cylinders 1 and 4
- For cylinders 2 and 3

The IC module and PCM use the low resolution engine speed signal to control ignition operation. The low resolution engine speed signal is derived from the crankshaft position (CKP) sensor, which is connected directly to the IC module.

DIAGNOSTIC AIDS
^ A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start. Test the battery positive voltage circuit for excessive resistance or corrosion. Refer to Wiring Repairs in Diagnostic Aids.
^ The PCM grounds will cause a NO START only if ALL of them are not making a good connection. Refer to Testing for Intermittent and Poor Connections in Diagnostic Aids.

IMPORTANT: The CMP sensor is only used for a misfire detection and is not part of the ignition system.

^ A loose CKP sensor may cause an intermitted NO START by moving away from the reluctor wheel. Inspect the sensor and matting surface for being clean and tight.

TEST DESCRIPTION

Electronic Ignition (EI) System Diagnosis - Steps 1-5:

Electronic Ignition (EI) System Diagnosis - Steps 6-12:

Electronic Ignition (EI) System Diagnosis - Steps 13-23:

The numbers below refer to the step numbers on the diagnostic table.
4. Repair the cause of the malfunctioning spark plugs before replacing.
5. Inspect for basic engine malfunction like low compression, burnt valves, a worn timing chain and worn gears, etc.
18. Any time the CKP sensor is removed the CKP system variation learn procedure must be performed. Programming and Relearning
22. The replacement PCM must be reprogrammed and the CKP system variation learn procedure must be performed. Programming and Relearning