System Diagnosis - Enhanced Ignition

This article has been updated with TSB 81-65-36

ENHANCED IGNITION SYSTEM (SYSTEM CHECK)

Wiring Diagram:

For additional wiring diagrams, Electrical Diagrams

DIAGNOSTIC INFORMATION AND PROCEDURES

CIRCUIT DESCRIPTION
This system includes the Distributor, the ignition coil, the ignition control module, the secondary wires, spark plugs, the VCM and the crank sensor. The ignition system is controlled by the Vehicle Control Module (VCM). The VCM monitors the information from various engine sensors, computes the desired spark timing and controls the dwell and firing of the ignition coil via an (IC) line to the ignition control module.

TEST DESCRIPTION
The numbers below refer to the step numbers in the diagnostic table.
The battery should be fully charged prior to any tests.
1. Perform the OBD system check before proceeding unless it was already performed.
2. Checks for proper output from the enhanced ignition system. The spark tester requires a minimum of 25,000 volts to operate. This check can be used in case of an ignition miss, because the system may provide enough voltage to run the engine but not enough to operate a spark plug under heavy load.
3. This test separates the distributor cap, rotor and ignition wires from the ignition coil in order to help identify a secondary ignition system problem.
5. This test checks the ignition control module, connections, and wiring.
12. This test begins to determine if the VCM is providing a signal to the ignition control module. If the VCM is not providing a signal to the ignition control module, the problem exists between the ignition control module and the VCM.
14. This test checks for a basic engine mechanical problem.