Ignition Control Module: Description and Operation

The Ignition Timing Control System is operated by the MPI controller. The MPI controller uses all of the engine condition and vehicle operating condition sensors (during normal driving conditions) to compute the correct spark advance or retard. The MPI controller uses two transistors in the power transistor assembly to control the ignition spark.

The power transistors function to control the ignition timing by interrupting the ignition coils primary current ground causing secondary circuit discharge. The power transistors are solid state components.