How to Install a 7-Way on a Trailer that Had a 4-Way and Wire Up Brakes

Published 01/29/2016

Products Featured in This Question

10 Gauge Wire - Blue Primary - Per Foot

(108)

$1.65

Trailer Wiring Junction Box

(824)

$35.47

Question:

I have a couple of brake assemblies in my cart to add electric brakes to my 22 ft boat trailer with 3500 dexter ezlube axle. It has backing plates. Current has flat 4 wiring for the lights, working fine. Is there a wiring kit for this purpose to add the brakes and switch to 7 pin ?

asked by: Patrick

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