Notice: The distributor used with the OBD II ignition system is located in a fixed, non-adjustable position. Do not adjust the engine base timing by rotating this distributor. Otherwise, crossfiring and damage to the distributor will result.

These ignition systems consist of a distributor with the following components:

The ignition system is controlled by the Vehicle Control Module (VCM). The VCM monitors information from various engine sensors. The VCM computes the desired spark advance timing, and controls the dwell. The VCM also controls the firing of the ignition coil via an ignition control line to the coil driver. For more detailed information, refer to Enhanced Ignition System Description in Engine Controls -- 5.0L, 5.7L.