System Description

Ignition System:

The engine ignition system consists of a distributor assembly, control circuits for ignition timing in the powertrain control module (PCM), a separate ignition coil / ignition control (IC) module assembly, a vacuum harness primary and secondary wiring, and the spark plugs. All ignition timing is controlled by the PCM; there is no "bypass" mode built into the ignition control module as in other ignition systems.

The ignition coil / ignition control (IC) module assembly provides spark to the distributor assembly, timed by signals from the PCM. Power (B+) for the ignition coil primary circuit and the ignition control module is supplied through the ignition switch. The PCM combines the camshaft position information supplied by the distributor with other system parameters and calculates the required spark advance. The PCM signals the ignition control module, which turns on the primary current to the ignition coil by grounding the primary circuit, and then turns it off by removing the ground. When the primary current flow stops, high voltage induced in the ignition coil secondary winding becomes the spark voltage for the spark plug. The spark voltage is delivered to the distributor assembly through the coil output (secondary) wire, and then directed to the proper spark plug connector by the distributor rotor.