Principles of Operation

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

When the vehicle's ignition key is in the RUN position voltage is supplied to upfitter relay control circuit. The upfitter relay closes and voltage is supplied to the upfitter relay box fuse 701 through circuit 1717 (VT/OG). The upfitter switch receives voltage through circuit 296 (WH/VT) and then distributes voltage to the 4 circuit control switches. When a control switch is closed it supplies voltage on circuit(s) 153 (VT/YE) upfitter relay #1, 154 (VT/LG) upfitter relay #2, 155 (GY/RD) upfitter relay #3, or 156 (GY/OG) upfitter relay #4 to one of the 4 upfitter relays in the upfitter relay box, closing the relay(s). Voltage is supplied to the switched side of the upfitter relays on circuits 1448 (OG/RD) upfitter relay #1, 1445 (RD/LG) upfitter relay #2, 1446 (RD/LB) upfitter relay #3, or 1447 (RD) upfitter relay #4. When the relay closes, voltage is supplied through the relay to the output circuits (blunt cut ends) 1936 (OG/LG) upfitter relay #1, 1933 (OG) upfitter relay #2, 1934 (OG/YE) upfitter relay #3, or 1935 (OG/LB) upfitter relay #4. The output circuits (blunt cut ends) supply voltage to the installed accessories connected to the upfitter relay box.