Electronic Ignition (EI) System Diagnosis

Electronic Ignition System Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The ignition system on this engine uses individual ignition coils and ignition control circuits for each cylinder. Ignition voltage is supplied to each bank of ignition coils. The engine control module (ECM) controls the ignition system operation. The ECM controls each coil using the ignition control circuits. The ECM commands the ignition control circuit low when a spark event is requested. The sequencing and timing are controlled by the ECM.

Diagnostic Aids

* The ignition coils for each bank are fused separately. If a fuse opens or the ignition voltage circuit opens between the fuse and the splice, all the ignition coils for one bank of the engine would be inoperative. If the ground circuit opens at the engine block, the ignition coils would be inoperative for one bank of the engine.

* Inspect the ignition coils for aftermarket devices. An aftermarket device connected to the ignition coil circuits, may cause a condition with the ignition coils.

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views A/C Compressor Clutch

Description and Operation

Electronic Ignition System Description Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Special Tools

EL 26792 - Spark Tester

For equivalent regional tools, refer to Special Tools Tools and Equipment.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the affected T8 ignition coil.

2. Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all the systems to power down. Test for less than 5 ohms between the ground circuit terminal A and ground.

• If greater than the specified range, repair the ground circuit for an open/high resistance.

3. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal B and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.

4. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal D and ground.

• If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.

5. Reconnect harness connector, Engine running, observe the Ignition Coil 1-6 Control Circuit Low Voltage Test Status on the scan tool. Test Status should be Ok or Not Run.

• If test status is Malfunction test for open or short to ground.

6. Engine running, observe the Ignition Coil 1-6 Control Circuit Open Test Status on the scan tool. Test Status should be Ok or Not Run.

• If test status is Malfunction test for open circuit.

7. Engine running, observe the Ignition Coil 1 6 Control Circuit High Voltage Test Status on the scan tool. Test Status should be Ok or Not Run.

• If test status is Malfunction test for short to voltage.

8. If all circuits test normal, test or replace the T8 ignition coil.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic repair.

* Ignition Coil Replacement - Bank 1 Ignition Coil Replacement - Bank 1

* Ignition Coil Replacement - Bank 2 Ignition Coil Replacement - Bank 2

* Control Module References Programming and Relearning for ECM replacement, programming and setup