Module, Powertrain Control: Operation: Operation: Notes

The Powertrain Control Module (PCM) receives input signals from various switches and sensors. Based on inputs it receives, the PCM adjusts and controls fuel injector pulse width, idle speed, ignition spark advance, ignition coil dwell, EVAP canister purge, cooling fan, and air conditioning.

If the PCM does not receive the crankshaft position signal within approximately one second of engine cranking, it deactivates the ASD relays and fuel pump relay. When these relays deactivate, power is shut off to the fuel injectors, ignition coils, heating element in the upstream oxygen sensors, fan control relays and the fuel pump. The two Auto Shutdown (ASD) relays and fuel pump relay are mounted externally, but turned on and off by the PCM.