Ignition Control Module: Description and Operation

Ignition Control System:

PURPOSE
The power transistor allows the ECU to control ignition coil triggering operation.

LOCATION
On the ignition coil bracket, near the master cylinder.

OPERATION
The EFC System control unit determines the optimum ignition timing from the crank angle signal and other engine operating information and transmits an operating signal to the power transistor, resulting in spark plug firing. The control unit signal causes primary current to flow to ground.
Actual spark timing is calculated from these factors:
^ Advance angle when starting the engine.
^ Advance angle at idle.
^ Advance angle determined by engine speed and load under all driving conditions except starting and idling.
A faulty power transistor does not set a trouble code.