Distributor Ignition (DI) System Diagnosis

DISTRIBUTOR IGNITION (DI) SYSTEM DIAGNOSIS

SYSTEM DESCRIPTION
This system includes the crankshaft position (CKP) sensor, the camshaft position (CMP) sensor, the ignition coil with the ignition control module (ICM), the secondary wires, the spark plugs, and the circuit conductors and connectors.

The powertrain control module (PCM) controls the ignition system. The PCM monitors the input signals from various engine sensors. The PCM controls the dwell of the ignition primary coil, computes the desired spark timing and firing of the ignition system via an ignition control (IC) timing control circuit to the ICM.

The Distributor Ignition (DI) System Diagnostic Table assumes the following conditions:
- The battery is fully charged.
- There is adequate fuel in the fuel tank.
- The fuel delivery system is functional.

DIAGNOSTIC AIDS
Engine mechanical conditions may prevent the distributor from rotating. Inspect the following if the distributor rotor does not rotate:
- A broken distributor drive shaft
- A worn or broken distributor drive gear
- A worn or broken camshaft timing chain and gears

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. If a repair is necessary.

TEST DESCRIPTION

Steps 1-9:

Steps 10-19:

Steps 20-32:

Steps 33-48:

Steps 49-50:

The numbers below refer to the step numbers on the diagnostic table.
3. This step is testing for a CKP sensor signal to the PCM.
4. This step is testing for an internally shorted CMP sensor.
9. This step is testing for spark output at more than one spark plug wire. The J 26792 Spark Tester requires a minimum of 25,000 volts to operate.
10. This step determines if spark is being delivered to the distributor cap.
20. This test is testing if the PCM is providing a timing control signal to the ICM.
21. This test checks for a basic engine mechanical problem.