Normal Operation
WARNING: This page is about a different car, the 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The DRL relay 1 coil voltage is supplied by the central junction box (CJB) through circuit 295 (LB/PK). When the parking brake is applied, the parking brake switch provides ground to the DRL relay 1 coil through circuit 162 (LG/RD). The DRL relay 1 is then energized, interrupting the voltage to the remaining DRL relays.
When the DRL relay 1 is not energized (the parking brake is released), the DRL relay 1 routes voltage to the DRL relay 2 through circuit 175 (BK/YE). The DRL relay 2 then routes the voltage to the DRL relay 3 coil through circuit 1032 (WH/BK). When the DRL relay 3 is energized, the voltage is routed to the headlamps.