Test Notes

NOTE: You should enter this pinpoint test only when you have been directed here.

To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault:
- Ignition Control Module (ICM)
- Ignition coil
- Spark plugs and high tension cables
- Distributor
- Arcing of secondary ignition components

This pinpoint test is intended to diagnose only the following:
- Harness circuit: IDM
- Powertrain Control Module (PCM)

DESCRIPTION
The Ignition Diagnostic Monitor (IDM) is an input signal to the PCM that verifies spark function based on the fly-back voltage created by the ignition coil primary discharge. This signal is transmitted from the Ignition Control Module (ICM) to the PCM. The IDM signal consists of a single pulse for each successful ignition event. Lack of an IDM pulse is used as an indication of intermittent and/or missing spark events.