Ignition Control Module: Description and Operation

Power Transistor/Ignition Coil:

The power transistors (2), located on the ignition coil brackets near the air intake boot, are low current switches. They allow the signal sent from the ECU (very low current) to activate the primary circuit in the ignition coils (much higher current). This induces high voltage in the secondary windings of the ignition coils, providing spark to the distributor cap and plugs.