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Home >> Isuzu >> 2003 >> Axiom Base, 4WD >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Ignition System >> DISTRIBUTORLESS Ignition System >> Ignition Control PCM Output

Ignition Control PCM Output

The PCM provides a zero volt (actually about 100-200 millivolts) or a 5-volt output signal to the ignition control (IC) module. Each spark plug has its own primary and secondary ignition coil assembly ("coil-at-plug") located at the spark plug itself. When the ignition coil 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. When the PCM shuts off the 5-volt signal to the TIN sensing 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 coil 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: