Ignition Control Module: Description and Operation

ICM Location:

PURPOSE
The Ignition Control Module (ICM) assists the Powertrain Control Module (PCM) by operating the ignition coils that fire cylinders 4/7 and 5/10. The ICM responds to commands from the PCM and controls ignition coil dwell and ignition timing.


OPERATION
The PCM and ICM do not communicate directly. The PCM receives vehicle speed input directly and transmits dwell data to the ICM.

The PCM receives both crankshaft and camshaft position directly. The PCM supplies an 8 Volt referance signal to the crankshaft, camshaft position sensor, and ICM.

CIRCUIT OPERATION
The Ignition Control Module (ICM) and Powertrain Control Module (PCM) communicate on circuits K137 and K138. Circuit K137 connects to cavity 7 of the ICM and Cavity 37 of the PCM. Circuit K138 connects to cavity 8 of the ICM and Cavity 38 of the PCM.