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How Does 7-Way and Brake Controller Install in 1973 Ford F-350


Wiring diagram for wire harness and controller in a 1973 Ford F-350 .And what controller would you recommend? Thanks


Helpful Expert Reply:

For a truck as old as yours it would be pretty hard to find a wiring diagram for installing the 7-way part # 20023 but I can help you figure it out using a circuit tester like the part # PTW2993. Basically you are going to need to test all of the wires of your taillights to determine their function and then wire to the 7-way using the included diagram.

Now hardwiring in a brake controller will be a similar process but you'll only have to test the wires at the brake switch till you find a source only hot when brakes are applied. Then you'll use the second diagram I attached to wire in the rest of it with the part # 5506 to supply the power and the ground for the controller.

Finally you will need to run a length of 10 gauge wire (part # 10-1-1) from the brake output circuit of the controller to the brake output circuit of the 7-way (blue wire). The # 10-1-1 is sold by the foot so you will need to order a quantity of the amount of feet you will need.

I noticed you referenced the P3 part # 90195 as well which is the controller I'd recommend. This is our best selling brake controller because of how well it works and how easy it is to setup. This is a proportional brake controller that senses the amount of braking the tow vehicle is applying and applies a proportionate amount to the trailer brakes. This will be the last brake controller you buy as it is incredibly reliable, works, well and is easy to use. It can easily be transferred to future vehicles as well.

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helpful expert reply by:
Jameson C

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