Ignition System: Testing and Inspection

Electronic Ignition (El) 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 eight individual ignition control (IC) circuits. Each bank of four ignition coils is connected to the PCM, power, or ground by the following circuits:

- Low reference

- Chassis ground

- Ignition 1 voltage

- The appropriate IC circuit

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


Diagnostic Aids

Important:

- Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

- For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit. Using this kit prevents any damage to the harness connector terminals.

Using Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the condition, the information included in the Freeze Frame/Failure Records data can help determine how many miles since the condition occurred.

Operate vehicle within the same freeze frame conditions, including the RPM, the load, the vehicle speed, and the temperature that you observed. This will isolate when the condition occurred.

For an intermittent condition, refer to Intermiffent Conditions.Symptom Related Diagnostic Procedures


Test Description

Electric Ignition (EI) System Diagnosis 1 Of 3:

Electric Ignition (EI) System Diagnosis 2 Of 3:

Electric Ignition (EI) System Diagnosis 3 Of 3:

The numbers below refer to the step numbers on the diagnostic table.

3. Monitoring the Misfire Current Counters determines if a fault is present.

4. A good indication that the fuse is open is more than 2 of the Misfire Current Counters incrementing on one side of the engine. Inspect the ignition 1 voltage circuit for a grounded circuit.

8. If the fuse is open and no condition can be found with the ignition coil/module circuits, inspect the injector circuits for being grounded.