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

This ignition system uses an ignition control module. The engine control module (ECM) controls the spark events by transmitting the timing pulses on the ignition control (IC) circuits to the cylinder ignition coils in firing order sequence. The ignition control module has the following circuits:

* An ignition 1 voltage circuit

* A ground circuit

* An IC circuit for each cylinder coil

* A low reference circuit

Diagnostic Aids

* An open/high resistance on the low reference circuit to the ignition coil may cause a misfire.

* An erratic or weak spark is considered a no spark condition.

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

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 Control Module References

Special Tools

EL 26792 - Spark Tester

Circuit/System Verification

Verify the following conditions. Refer to Spark Plug Wire Inspection Testing and Inspection and Ignition System Specifications [1][2]Specifications.

* The ignition coil and spark plug wires are correctly connected

* The spark plug wire resistance is within specifications

* The correct spark plug type

* The correct spark plug gap

* The correct spark plug torque

If a condition was found
Repair or replace as necessary.

If a condition was not found
Refer to Circuit/System Testing.

Circuit/System Testing

Note: Do not perform this diagnostic procedure unless you were sent here from a misfire DTC or the Engine Cranks But Does Not Run diagnostic.

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the Ignition Control Module. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 5 ohms between the ground circuit terminal E and ground.

• If 5 ohms or greater

1. Ignition OFF.

2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, repair the open/high resistance in the ground connection.

• If less than 5 ohms

3. Test for less than 5 ohms between the low reference circuit terminal D and ground.

• If 5 ohms or greater

1. Ignition OFF, disconnect the X2 harness connector at the Engine Control Module.

2. Test for less than 2 ohms in the low reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, replace the Engine Control Module.

• If less than 5 ohms

4. Ignition ON.

5. Verify a test lamp illuminates between the ignition circuit terminal F and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF, remove the test lamp.

2. Test for less than 2 ohms in the ignition circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF, remove the test lamp.

2. Test for infinite resistance between the ignition circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance, replace the Ignition Control Module.

• If the test lamp illuminates

6. Test or replace the Ignition Control Module.

Component Testing

Note: You must perform the Circuit/System Testing before proceeding with Component Testing.

1. Ignition OFF, connect the EL 26792 - Spark Tester to each spark plug wire.

2. Engine running.

3. Verify the spark output of the Ignition Control Module at each spark plug wire.

• If any have no output or the output is weak
Replace the Ignition Control Module.

• If the output is good

4. All OK.

Repair Instructions

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

* Ignition Coil Replacement Service and Repair

* Spark Plug Replacement Service and Repair

* Spark Plug Wire Replacement Service and Repair

* Control Module References Control Module References for engine control module replacement, programming, and setup.