Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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NB - Testing Notes

NOTE:
You should enter this Pinpoint Test only when you have been directed here from Diagnostic Routines.

REMEMBER:
To prevent the replacement of good components, be aware that the following non-Electronic Engine Controls (EEC) areas may be at fault:

- Ignition Control Module (ICM)

- Electronic Ignition coil pack(s)

- Spark plugs and high tension cables

Crankshaft Position (CKP) sensor

- Camshaft Position (CMP) sensor, if equipped

- Arcing of secondary ignition components


This Pinpoint Test is intended to diagnose only the following:

- Harness Circuits: Ignition Diagnostic Monitor (IDM) and Dual Plug Inhibit (DPI)

- Powertrain Control Module (PCM) (12A65O)

Description:
The IDM is an input signal to the PCM that verifies spark function based on the flyback voltage created by the ignition coil primary discharge. This signal is transmitted from the 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 event.