Ignition System: Description and Operation

The Chrysler-based computerized ignition system controls ignition timing and dwell via a micro-processor and various input signals. It operates in two modes:

START MODE
During start-up and until engine speed reaches a specific RPM, ignition timing is controlled by the distributor.

RUN MODE
After start, once the engine reaches a specified RPM, the micro-processor in the control unit is activated. Timing is then controlled by varying the dwell angle per data stored in the ECU memory.

To ensure accurate basic timing, it is important that the ignition is in "RUN" mode.