System Operation: Acc
WARNING: This page is about a different car, the 2013 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
When the BCM-B receives the ACC voltage input from the ignition switch it activates the RUN/ACC bus and the RUN/ACC relay, providing ignition accessory power to the various vehicle systems and modules. The BCM-B also sends out the ignition mode message on the MS-CAN and the HS-CAN .