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 various 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:

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.

Power Transistor:

The power transistor is a type of switch that allows a very low amount of current (from the ECU) to control a large amount of current (negative side of coil).