Ignition Control Module (ICM) and Ignition Coils

The ICM is connected to the PCM by an Ignition Control (IC) circuit. The ICM also has a ground circuit and shares an ignition 1 voltage supply with the ignition coil. The coil driver in the ICM controls current through the ignition coil based on signal pulses from the PCM. There is no back-up or by-pass function in the ICM.