How to Install 7-way Trailer Connector on Trailer

Updated 04/14/2014 | Published 04/12/2014

Products Featured in This Question

10 Gauge Wire - Blue Primary - Per Foot

(108)

$1.65

Trailer Wiring Junction Box

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$35.35

Question:

I have a Toyota Tundra with a 7 way connector. The trailer I have uses the 4 way. I have the adapter to connect to the Tundra. No issue there. I want to add electric brakes to the trailer, but I cannot find any instructions on wiring. I need to convert the existing wiring to a seven way. Is there a converter/connector that lets you plug in the four way and then the brake wiring is a separate set of wires coming out of the connector?

asked by: Emmett T

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: Mike L