Parts Needed to Add 7-Way and Junction Box to Trailer

Updated 03/28/2017 | Published 03/27/2017

Products Featured in This Question

10 Gauge Wire - Blue Primary - Per Foot

(108)

$1.65

Trailer Wiring Junction Box

(824)

$35.35

Question:

Hello, I recently bought a tandem axle trailer with electric brakes but the brakes are not hooked up but have the two wires coming off them. the trailer has the 4 wire plug for the lights and all the lights work and are wired right. I was wondering how I should go about wiring the brakes in. I know I will need a 7 way plug and id assume use a junction box? not to sure any help would be appreciated thanks.

asked by: Zach

Helpful Expert Reply:

If you are wanting to add brakes to your trailer, the correct way to to it would be to remove the 4-pole connector and install a 7-way harness/plug like part # H20046. You would use a junction box like part # 38656, and some 10 gauge wire like part # 10-1-1 to run the brake output circuit from the junction box to the brake assemblies. Each brake magnet will have two wires exiting it. One wire will ground to the trailer frame, the other will attach to the brake output circuit. The junction box provides a neat and weather-protected way of joining the trailer connector to the trailer wiring.

The wires from the existing 4-pole would connect to the appropriate terminals in the junction box, and the wires from the # H20046 would connect using the same terminals. Be sure to look at the table I provided, as the wire color code for the H20046 wiring won't match up color for color with the typical trailer wiring code.

I have linked you to some excellent videos showing how the junction box and wiring harness is installed.

expert reply by: Jameson C