Computer Controlled Shutdown
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2006 Mercury Mountaineer, 2006 Mercury Monterey, 2006 Mercury Montego, 2006 Mercury Milan, and 2006 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.
The powertrain control module (PCM) controls the electronic engine control (EEC) power relay when the ignition key is turned to the ON or START position, by grounding the PCM relay control (PCMRC) circuit. After the ignition key is turned to the OFF, ACC or LOCK position, the PCM will stay powered up until the proper engine shutdown occurs.
The ignition switch position run (ISP-R) and the injector power monitor (INJPWRM) circuits provide the ignition key state input to the PCM. Based on the ISP-R and INJPWRM signals the PCM determines when to power down the EEC power relay.