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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General Description

The ignition control module (ICM) is located on top of the rear camshaft cover. The ICM performs the following several functions:
^ Monitors the on-off pulses produced by the 2 crankshafts and the camshaft position sensor.
^ Creates a 4X and 24X reference signal (4X ref high and 24X crank) sent to the powertrain control module (PCM) for ignition control.
^ Creates a camshaft reference signal (1/2X cam high) sent to the PCM for fuel injection control.
^ Provides a ground reference (ref. lo/cam lo) to the PCM.
^ Provides a means for the PCM to control spark advance (bypass and ignition control), called ignition control mode.
^ Provides a limited means of controlling spark advance without PCM input, called module mode.

The ICM is not repairable. When a module is replaced, the remaining components must be transferred to the new module.