Normal Operation - Vehicles not equipped with a Circuit Deactivation Ignition Module (CDIM)
WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition switch is placed in the RUN position, voltage is supplied to the internal logic of the Body Control Module (BCM) via the run/acc and run/start circuits. The BCM communicates the inputs internally to provide a ground to the run/start relay control circuit. When activated, the run/start relay provides voltage to the BCM run/start circuits.