Troubleshooting Brake Controller Voltage Drop at Rear of 7-Way

Question:

I ran a new wire from my brake controller to the plug on my bumper. About 6”behind the controller on the new wire it reads 12v and at the back of the plug only 5v is my brake controller bad?

asked by: Dustin

Expert Reply:

If you are seeing 12 volts right behind the brake controller on the output circuit but then only 5 volts on same circuit right behind the 7-way that is probably not an issue with the brake controller but instead the wiring. That much of a voltage drop would typically mean the gauge wire used there is too thin. You want 10 gauge wire for this circuit for this reason. Also it could be a short on the circuit, but you most likely would see an error on your brake controller. Especially if it's a P3 part # 90195 like you referenced.

expert reply by: Jameson C