Ignition Circuit Sense

The ignition switch power feeds to the PCM originate from the Integrated Power Module (IPM) after it determines what position the ignition key is in. The ACC and Run/Start feeds are hard wired from the IPM to the PCM. There is no hard wire Start feed to the PCM, because the IPM indicates via a CAN bus message to the PCM when the key is in the START (Crank) position.