Ignition Control Module: Description and Operation

IGNITION COIL/ICM ASSEMBLY

Each Ignition Control Module (ICM) has the following circuits:
^ An ignition 1 voltage circuit
^ A chassis ground
^ An ignition control circuit for each cylinder
^ A low reference circuit
The PCM controls spark by pulsing the ignition control circuits to the ICM to trigger the coils and tire the spark plugs. The PCM and ICM are internally protected against shorts to power and ground on the ignition control circuits.

The spark plugs are connected to each coil by a short boot. The boot contains a spring that conducts the spark energy from the coil to the spark plug. The spark plugs are tipped with platinum for long wear and higher efficiency.