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Locating Wires for Electric Brake Assemblies on Used Car Hauler

Question:

I just purchased a used car hauler. Apparently the last owner tore off the 7 pin and replaced it with a 4 pin. Of course now the brakes aren’t connected. I noticed that there is a black and white wire running to the brakes. Everything I read talks about a blue wire. I’m totally confused about where do those two wires connect to the 7 pin.

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Helpful Expert Reply:

Each brake assembly on a trailer will have two wires coming out the back; a wire for ground and a wire for power. The ground wire can simply be attached to a clean, bare metal surface on the trailer frame. The power wire is what will run from the assemblies up to the front of the trailer to the 7-Way connector at the 5 o'clock position. This wire is indeed usually a 10-gauge wire with blue insulation like # 10-1-1. It's possible that the brake wire on your trailer is a 12-gauge wire instead, like # 12-1-1, which would be black in color.

I have attached a couple wiring diagrams for typical 7-Way wiring on a trailer that you might find helpful. I have also attached an article on adding electric brakes to a trailer. The wiring section is toward the end of the article.

Please just let me know if you have any further questions.

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helpful expert reply by:
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Chris R

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