Ignition Timing Control (Power Transistor) System

Ignition Timing Control System:

The Ignition Timing Control System operates by the ECU controlling the ignition timing through the power transistor. The ECU uses all of the engine condition and vehicle operating condition sensors (during normal driving conditions) to compute the correct spark advance or retard (during engine cranking, the ignition timing is fixed at 5°BTDC). The ECU uses the power transistor to control the ignition spark.

Power Transistor Location:

Power Transistor:

The power transistor (located on the intake manifold) functions to control the ignition timing by interrupting the ignition coil primary current ground causing secondary circuit discharge.