Engine Control Module: Description and Operation

SYSTEM OPERATION

Powertrain Control Module:

The PCM regulates the ignition system. The PCM supplies battery voltage to the ignition coil through the Automatic Shutdown (ASD) Relay. The PCM also controls the ground circuit for the ignition coils. By switching the ground path for the coil on and off, the PCM adjusts ignition timing to meet changing engine operating conditions.

During the crank-start period the PCM advances ignition timing a set amount. During engine operation the following inputs determine the amount of spark advance provided by the PCM.
- Intake air temperature
- Coolant temperature
- Engine RPM
- Available manifold vacuum
- Throttle position sensor

The PCM also regulates the fuel injection system.