Functional Description - Ignition Coils

There is one ignition coil for each spark plug. Each ignition coil is mounted over the top of the spark plug installed in a cavity of the cylinder head. Each coil consists of the following:

• Coil assembly.
• Primary electrical connector.
• Secondary conductor.
• Spark plug boot.

The ignition coils operate in the following manner:

• The Ignition System Control Module (ISCM) provides a power supply and ground (control) for the ignition coils.
• To turn on the ignition coil and energize the primary circuit, the ISCM simultaneously turns on the power supply and control circuit to the ignition coil.
• When spark plug firing is commanded by the Powertrain Control Module (PCM) on the command circuit, the ISCM turns off the power supply and control circuits to the ignition coil and the ignition coil fires the spark plug through the secondary circuit.
• The ION circuit provides secondary ignition feedback to the ISCM. This feedback signal is used to detect misfire by determining if a complete burn was present.