Normal Operation
WARNING: This page is about a different car, the 2004 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.
Under normal operation the PDB supplies constant power to the starter relay on circuit 30-BB13 (RD) through fuse 121 (30A). When the key is placed in the START position, with the vehicle in PARK or NEUTRAL, the TR sensor provides power on circuit 50S-BB12 (GY) and the instrument cluster provides ground on circuit 31S-BB12 (BK/YE). The coil of the relay is energized and sends power to the starter motor on circuit 50-BB10 (GY/BK).