Ignition Control Module (ICM)

The ICM provides PCM with engine speed (4X REF HI), fuel control (l/2X CAM HI), ignition control (BYPASS and IGNITION CONTROL) and ground reference (REF LO/CAM LO) information. The ICM also provides PCM with a signal to indicate if ICM has identified a problem with one of its three sensors (24X CRANK). All of these signals are varying voltages that have a maximum of 5 volts.

The PCM uses ICM information for fuel control, idle speed control and ignition control (which it outputs back to ICM). A fault with any of these signals between ICM and PCM will cause various driveability conditions and should set a PCM Trouble Code.