Ignition Control PCM Output

DESCRIPTION AND OPERATION
The Powertrain Control Module (PCM) provides a zero volt (actually about 100 mV to 200 mV) or a 5 volt output signal to the ignition control (IC) module. 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 and creates a magnetic field in the coil. 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 DTC P0351.