Electronic Ignition (EI) System Diagnosis

ELECTRONIC IGNITION (EI) SYSTEM DIAGNOSIS

CIRCUIT DESCRIPTION
The electronic ignition system uses an individual ignition coil for each cylinder. The powertrain control module (PCM) controls the ignition operation through 8 individual ignition control (IC) circuits. Each bank of four ignition coils is connected to the PCM, power, and ground by the following circuits:
- The low reference
- The ground
- The Ignition 1 voltage
- The appropriate IC circuit

The PCM triggers an ignition coil by grounding the appropriate IC control using information from the crankshaft position (CKP) and camshaft position (CMP) sensors.

DIAGNOSTIC AIDS
- The CKP signal must be available for the engine to start. The CMP signal is not needed to start and operate the engine. The PCM can determine when a cylinder is on either the firing or exhaust stroke by the 24X signal.

IMPORTANT: A missing CMP sensor signal may cause a long crank condition.

- Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1 - 12:

Steps 13 - 24:

Steps 25 - 35:

The number below refers to the step number on the diagnostic table.
4. Monitoring the misfire current counters determines if a fault is present.