Ignition Control Module: Description and Operation

Ignition Control Module:

The Ignition Control Module (ICM) with Computer Control Dwell (CCD), and the Powertrain Control Module (PCM) control the ignition coil charge timing.

The Ignition Diagnostic Monitor (IDM) is a function of the ICM. The ICM sends information on system failures to the PCM which stores the information for diagnostic self tests. The IDM signal also is used to drive the tachometer.