Trailer Wiring has 3 Wires for Brakes But Magnets Only have 2 Wires

Updated 01/18/2017 | Published 01/17/2017

Question:

I have a tandem axle trailer with 3 wires running underneath it, if get a hub/drum assembly and brakes, should I still get the brake that only has two wires? Does it matter which wire I tap into or are they all the same? I think they are all connected together and they are green.

asked by: Daine J

Helpful Expert Reply:

Electric trailer brake magnets only have a power wire and a ground wire (doesn't matter which is which). The power wires will attach to whichever of the 3 wires carries the brake signal from the brake controller. One of the other wires must be a ground but you can ground the magnets to any clean metal surface. The third wire could be for something else or it could be a power or ground that tees off from the main ground/power wire.

expert reply by: Michael H