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 individual Ignition Coil assemblies for each cylinder. The engine control module (ECM) controls the spark events by transmitting the timing pulses on the ignition control circuits to the individual ignition coil assemblies in firing order sequence. Each ignition coil has the following circuits:

* An ignition voltage circuit

* A ground circuit

* An ignition control circuit

Diagnostic Aids

* This test procedure requires that the vehicle battery has passed a load test and is completely charged.

* There is an adequate supply of fuel in the fuel tank.

* When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect both mating electrical terminals for corrosion and terminal tightness.

* Use the EL 35616-E - Terminal Test Kitfor any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness terminals.

* A slight to moderate resistance in the ignition voltage circuit can cause a misfire condition or a crank/no start concern.

* Extended engine cranking time, will foul the spark plugs with excessive fuel and cause a crank/no start condition.

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

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 for scan tool information

Special Tools

* EL 26792 - HEI Spark Tester

* EL 35616-E - Terminal Test Kit

* EN 36012-A - Ignition System Diagnosis Harness

For equivalent regional tools, refer to Special Tools Tools and Equipment for scan tool information

Circuit/System Verification

Note: Verify that the engine is in good mechanical condition before continuing with this diagnostic.

Observe the engine controls schematic for the ignition module/coils, and review the ignition system specifications to verify the following concerns:

* The ignition modules/coils are correctly wired and connected.

* The proper spark plug type, refer to Spark Plug Inspection Testing and Inspection.

* The proper spark plug gap and torque.

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, disconnect the T8 Ignition Coil electrical connector.

2. Ignition OFF, all vehicles system OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohms between the low reference circuit terminal C 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.

3. Test for less than 5 ohms between the ground circuit terminal B and ground.

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

4. test for less than 2 ohms between the ignition voltage circuit terminal A and the fuse.

• If greater than the specified range, repair the ignition voltage circuit for high resistance.

5. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal A 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.

6. If all circuits test normal, test or replace the ignition coil assembly.

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

* Control Module References Control Module References for replacement, setup, and programming.