bing tracking image
Q & A Icon

Locating Wires for Electric Brake Assemblies on Used Car Hauler


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.


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.

click to enlarge
click to enlarge
helpful expert reply by:
Chris R

Products Referenced in This Question

Product Page this Question was Asked From

Q & A Icon

Similar Expert Q&A Pages

See More Q&A Expert Answers >>