Normal Operation
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.
Under normal operation, constant power is supplied to the starter relay on circuit 1050 (LG/VT). When the key is placed in the START position, with the vehicle in PARK or NEUTRAL, the TR sensor provides power to the starter relay coil on circuit 33 (WH/PK) and the PCM provides ground to the starter relay coil on circuit 1419 (LG/YE). When the coil of the relay is energized it sends power to the starter motor on circuit 113 (YE/LB).