How to Install a 7-Way Trailer Connector Harness on a 5th Wheel Trailer

Updated 07/25/2014 | Published 07/24/2014

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Question:

Hi John, Thanks for your help on the height of camper to truck bed rails. Someone took my wiring from my camper and I dont have a clue on how to wire the new plug. Pin box has a switch with 2 black wires, 1 Blue wire, 1 Black wire, looks to be 2 green wires,1 Brown wire, 1 Red wire,1 white wire. Plug that goes to truck has 1 Blue, 1 White, 1 Black, 1 Yellow, 1 Green, 1 Red, 1 Brown. Thank You. Place help ASAP I need to move the camper.

asked by: Jack G

Expert Reply:

The switch on your pin box is probably the breakaway switch. One wire from the switch will go to a 12v battery on the trailer and the other wire will tap into the electric brake wire on the trailer (typically a blue wire). I have attached an installation video for a breakaway kit to give you an idea of how it is installed.

The wires that you listed on your trailer are not all common colors, so the best way to determine the function of each wire is to use an independent 12 volt power source such as a vehicle battery to apply power to each wire to determine its function.

The plug that you have does have typical RV wire colors. I have listed the typical RV style colors and functions below.

Blue - Electric Brakes
White - Ground
Black - 12 Volt Battery Charge
Yellow - Auxiliary Power/Reverse Lights
Green - Running Lights
Brown - Right Turn/Brake Light
Red - Left Turn/Brake Light

Check out the trailer wiring help article that I attached. Keep in mind, not all trailer manufacturers stick with the same color code, so it is important to wire the colors by function. To make the process easier, I recommend using a junction box like part # 38656. This will make it easier to rewire the trailer if the plug is stolen again. I have attached a junction box and 7-way wiring harness installation video that may help as well.