Ignition Control Module: Description and Operation

Power Transistor:

Ignition Timing Control System:

PURPOSE/OPERATION
The power transistor controls ignition current by interrupting the ignition coil primary ground causing secondary circuit discharge.

The engine control module controls ignition timing through the power transistor. The power transistor is a type of switch that allows a very low voltage from the engine control module to control a larger amount of voltage, the negative side of coil. During engine cranking, the ignition timing is fixed at 5°BTDC