Ignition Control Module: Description and Operation

Power Transistor:

PURPOSE
Activates the primary circuit in the ignition coil.

LOCATION
On the intake manifold in front of the distributor

OPERATION
The power transistor is a low current switch. It allows the signal sent from the ECU (very low current) to activate the primary circuit in the ignition coil (much higher current). This induces high voltage in the secondary windings of the ignition coil, providing spark to the distributor cap and plugs.