Computer Controlled Shutdown

The powertrain control module (PCM) controls the PCM power relay when the ignition is turned to the ON or START position, by grounding the PCM relay control (PCMRC) circuit. After the ignition is turned to the OFF, ACC or LOCK position, the PCM stays powered up until the correct engine shutdown occurs.

The ignition switch position run (ISP-R) circuit provides the ignition state input to the PCM. Based on the ISPR signal the PCM determines when to power down the PCM power relay.

The PCM software monitors the parameters for the controlled systems to make sure that all values have met a threshold for shutdown.