Ignition Control Module: Description and Operation

The Ignition Timing Control System operates by the Multi-Point Injection (MPI) computer controlling the ignition timing through the power transistor. 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 the power transistor to control the ignition spark.

The power transistor functions to control the ignition timing by interrupting the ignition coil primary current ground causing secondary circuit discharge. The power transistor is a solid state component.