Ignition System: OPTI-Spark

The PCM supplies and monitors two 5-volt reference signals to the Opti-Spark ignition control module inside of the sealed distributor, mounted behind water pump. Ignition module is capable of providing both the 4X and 180X timing pulses each crankshaft revolution. Using these timing pulses, PCM processes ignition spark timing and sends an IC signal to the ignition coil module to activate the secondary ignition system.

After computing necessary changes to ignition timing, PCM triggers ignition coil through the ignition coil driver. Unlike other type ignition systems, Opti-Spark does not use a by-pass circuit. Timing is always in EST mode.

By comparing 4X and 180X signals to each other, PCM can determine the location of the position of cylinder No. 1 and TDC position. Engine will not run if the 4X reference signal is missing. If either signal is missing, a diagnostic trouble code will set in PCM memory.