Hopkins 7 Way Molded Plug Wiring and Junction Box for a Boat Trailer Wiring Harness

Updated 11/01/2021 | Published 10/31/2021

Products Featured in This Question

Hopkins 7-Way RV Style Connector with Molded Cable - Trailer End - 8' Long - RV Standard

(912)

$46.90

Trailer Wiring Junction Box - 7 Terminals - Polypropylene

(247)

$15.21

Question:

My trailer wiring harness has 2 black wires, 2 white wires and 2 green wires. How do i match them up to the 7 blade Hopkins molded trailer plug? The wires coming from the plug, if I match them by color does not work. Very confused

asked by: Ryan W

Expert Reply:

There's not a universal way that trailers are wired. I have attached a diagram showing the three typical ways and this should also help you to connect to the 7-way harness you purchased once you identify your wires. Yours is obviously different, thank you for including the picture. To identify the wires on the trailer you will need to apply 12V power from a car battery to see what function each wire activates. Ground the battery negative terminal to the trailer frame and then one by one apply +12V power to each wire to see what each wire connects to. Since you already have the Hopkins 7-Way RV Style Connector with Molded Cable item # H20046, I recommend using the Trailer Wiring Junction Box item # 3375601100. This junction box provides a centralized place to make all your wiring connections. It will provide a professional looking installation that will keep all your wiring connections protected from the elements.

expert reply by: Jerred H