Ignition Control PCM Output

IGNITION CONTROL PCM OUTPUT
The PCM provides a zero volt (actually about 100 mV to 200 mV) or a 5-volt output signal to the ignition control (IC) module. Each spark plug has its own primary and secondary coil module ("coil-at-plug") located at the spark plug itself. When the ignition control (IC) module receives the 5-volt signal from the PCM, it provides a ground path for the B+ supply to the primary side of the coil-at-plug module. This energizes the primary coil and creates a magnetic field in the coil-at-plug module. When the PCM shuts off the 5-volt signal to the ignition control module, the ground path for the primary coil is broken. The magnetic field collapses and induces a high voltage secondary impulse which fires the spark plug and ignites the air/fuel mixture.
The circuit between the PCM and the ignition control (IC) module is monitored for open circuits, shorts to voltage, and shorts to ground. If the PCM detects one of these events, it will set one of the following DTCs:
^ P0351: ICM Fault on Cylinder #1
^ P0352: ICM Fault on Cylinder #2
^ P0353: ICM Fault on Cylinder #3
^ P0354: ICM Fault on Cylinder #4
^ P0355: ICM Fault on Cylinder #5
^ P0256: ICM Fault on Cylinder #6