The distributor ignition (DI) system uses the crankshaft position (CKP) sensor in order to provide a timing input to the engine control module (ECM). Ignition control (IC) spark timing for each cylinder is based on this input. The ECM provides the ignition timing signal to the ignition control module (ICM) to control the ignition coil. Each timing pulse detected by the ICM allows it to energize the ignition coil. A large secondary ignition voltage is induced in the secondary coil by the primary coil. This high voltage is switched to the correct spark plug by the distributor.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Engine Control Module Connector End Views

Electrical Information Reference

Scan Tool Reference

Engine Control Module Scan Tool Information

Important: 

•	Do not perform this diagnostic procedure if you were not sent here from a misfire DTC or the Engine Cranks but Does Not Run diagnostic.

•	It may be necessary to perform step 1 on a few of the spark plug wires.

1. Ignition OFF, connect the J 26792 to the boot of a spark plug wire of a cylinder and ground.

Important: An erratic or weak spark is considered a no spark condition.

2. Engine cranking, the spark tester should spark.

1. Ignition OFF, inspect the spark plug wires, and coil wire for the following:

•	Mis-routed wires

•	Cracks in the insulation

•	Improper connection at the spark plugs and distributor cap

⇒	If a condition is found, repair as necessary.

2. Disconnect the harness connector at the ICM.
3. Test for less than 5 ohms between the ground circuit terminal C and ground.

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

4. Ignition ON, load test for B+ between the ignition voltage circuit terminal A and ground.

⇒	If less than the specified range, repair the ignition voltage circuit for an open/high resistance.

5. Engine cranking, test for greater than 3 Hz between the ignition control circuit and ground.

⇒	If less than the specified range, test the ignition control circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.

6. Ignition OFF, connect the ICM harness connector. Disconnect the harness connector at the ignition coil.
7. Ignition ON, load test for B+ between the ignition voltage circuit terminal A and ground.

⇒	If less than the specified range, repair the ignition voltage circuit for an open/high resistance.

8. Connect a test lamp between the coil driver circuit terminal C and B+.
9. Engine cranking, the test lamp should blink.

⇒	If the test lamp remains ON all the time, test the ignition control circuit for a short to ground. If the circuit tests normal, replace the ICM.

⇒	If the test lamp remains OFF all the time, test the ignition control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ICM.

10. Ignition OFF, connect the ignition coil harness connector. Disconnect the ignition coil wire from the distributor cap. Connect the J 26792 between the boot of the coil wire and ground.
11. Engine cranking, the spark tester should spark.

⇒	If the spark tester does not spark, test the coil wire for an open/high resistance. If the coil wire tests normal, replace the ignition coil.

12. Ignition OFF, remove the distributor cap.
13. Engine cranking, verify the distributor rotor is rotating.

⇒	If the distributor rotor does not rotate, repair the engine mechanical condition.

14. If all circuits test normal, inspect and replace the distributor cap and rotor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.