Ignition Control Module: Description and Operation
DESCRIPTIONIgnition Control Module (ICM):
The Ignition Control Module (ICM) is a microprocessor-based device with coil drivers which make decisions about spark dwell and coil firing.
OPERATION
The ICM receives crankshaft position and speed information from the Crankshaft Position (CKP) sensor, and desired spark advance information from the Powertrain Control Module (PCM) supplied SPark OUTput (SPOUT) signal. It uses this information to direct which ignition coil to fire, and controls the turn ON and turn OFF of that ignition coil to achieve the correct dwell and spark advance. The ICM also synthesizes a Profile Ignition Pickup (PIP) signal. The PIP signal is used by the PCM for engine speed information and fuel injector timing. The Ignition Diagnostic Monitor (IDM) signal sends electronic ignition system failure information to the PCM, where the information is stored for use during diagnostic test mode. The IDM also provides the signal to drive the tachometer.