Wiring a 7-Way RV Connector on a 1989 Ford F-250 Truck for Towing a Trailer with Electric Brakes

Published 11/23/2011

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Question:

Hello, I just installed a t one connector and plugged it into a 7 way connector that has a black, purple, white and blue ready to run the brakes. I need the additional wiring and circut breakers and such to complete the package along with some instructions would be nice. I have a hayes sycronizer brake control that I pulled from old truck but just unplugged it from the installed harness. What can I do? Thanks

asked by: Richard

Expert Reply:

Lets start at the back of your 1989 Ford F-250 pickup. I assume that you installed a T-One Wiring Harness, # 118316, and a 4 Pole to 7 Pole adapter, like part # 37185, and that the stop, turn and tail light signals are plugged into the 4-way connector on the adapter and working. The White wire should be grounded to the truck frame, clean the area you will be connecting this wire to for a solid ground.

Next, the purple wire is for the center pole in the 7-Way connector. This wire should be attached to the reverse light circuit behind one of the taillights. Use a circuit tester, # PTW2993 if needed, to be sure you find the correct wire to splice into and run a 12-gauge wire, # 12-1-1 to the correct circuit.

Next, you will need to run the black and blue wire from the 7-Way forward under the truck. Use an appropriate length of 10 gauge wire, # 10-2-1. Attach the black wire from the 7-Way to the black wire in the wire bundle and attach the blue wire from the 7-Way to the white wire in the wire bundle.

Now, at the front of the vehicle under the hood, attach the black wire to the positive post of the vehicle battery, using a 40 amp inline circuit breaker, # PK54540 to protect the circuit. Then run the white wire into the drivers side of the cab through a grommet in the firewall.

Next, use another length of jacketed wire and run the black wire through a 30 amp inline circuit breaker, # PK54530, from the positive battery post and the white wire from the negative battery post into the cab of the vehicle.

Now, inside the cab, mount your brake controller, and attach the white ground wire to the white ground wire exiting the brake controller. Then attach the black power wire to the black power wire exiting the brake controller. The white brake output wire that was previously ran from the back should be attached to the blue wire exiting the brake controller.

Finally, use the circuit tester to locate the cold side brake switch wire located under the dash at the brake pedal. This wire will have power only when the brake pedal is pressed. On many Ford trucks this wire is light green or red. Test to be sure you have the correct wire.

We have a complete brake controller installation kit that includes all of the parts needed to complete a hard wire brake controller installation. I have linked instructions for this kit for you to review along with a video of this kit being installed on a friend of mines 1979 Ford F-250.