Wire Colors for Installing 7-way Connector on 1991 Ford F250
Updated 10/27/2009 | Published 10/26/2009
Question:
Just bought a 1991 F250 to have for a farm truck. Want to wire a 7 pin receptacle on the back. Can you tell me color code of the wires coming from the truck that contro each function. The factory harness is an odd assortment of colors from what Im used to. Mostly had GM stuff before. Oddly enough there are 8 wires in the factory harness but I assume one has been added from something. Havent really traced it down. Have a prodigy I bought from you folks that I plan to replace the old controller on the truck once plug is worked out. Old plug had been removed so I dont have much to go on.
asked by: Danny K
Expert Reply:
According to the information I have, the wires serve the following functions. The orange wire with a blue stripe controls the right turn/ brake light. The light green wire with the orange stripe controls the left turn/ brake light, the brown wire carries the signal for the running/ marker lights and the black or gray wire is the ground. The black wire with a pink stripe carries the signal for the reverse lights.
This will eliminate 5 wires, leaving 3 remaining. One of the remaining wires will carry the brake controller output voltage. The easiest method of finding which wire carries this signal would be to go ahead and install the brake controller, and verify this wire by using a circuit tester, such as part # PTW2993, while the override switch is activated. One of the remaining wires carries the 12-volt accessory power for the trailer. The last wire might be for a third brake light or dome light for a bed cover.
