Ignition Control Module: Description and Operation

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.