Troubleshooting Trailer Brakes that Are Using 12 Gauge Wire

Updated 05/03/2021 | Published 04/30/2021

Products Featured in This Question

Electric Trailer Brake Assembly - 10" - Left Hand - 3,500 lbs

(245)

$47.74

10 Gauge Wire - Blue Primary - Per Foot

(104)

$1.84

Question:

I did a complete brake job on my trailer as well as rewiring from factory 18 gauge wire to 12 gauge wire. I wired each axle individually, so I have 2 wires coming up front to the control box. I was getting an error on the truck display to check trailer wiring, and I had no brakes at all. Trying to source the problem I made sure the ground was proper, then decided to test each axle. Ive determined that 1 axle is causing the error, while the other works just fine on its own. Im having doubts of a problem with the newly run wire. I know it says the magnet wires can be hooked up either way. Do they have to be the same on the circuit? For example, if I put one to ground would the same wire have to be to ground on the other brake on that circuit? Otherwise, any suggestions to figure out whats up?

asked by: Chris

Expert Reply:

The first thing that stands out to me is that you used 12 gauge wire on a tandem axle setup when it's 10 gauge wire that is widely considered to be the minimum. I'd maybe try going up to 10 gauge wire like # 10-1-1 and you should see the issue go away as the wiring is probably just not able to handle the amperage needed.

The brake magnets can be wired in either configuration so the issue you mentioned would not be the problem either. But also check for any bare wire touching metal of the wiring and fix as needed as that would cause a short.

expert reply by: Jameson C