Replacement 7-Way Trailer Wiring Junction Box Installation

Updated 03/07/2019 | Published 03/06/2019

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Question:

The 7 way plug pulled completely out of the junction box. Including the red #8 wires, Cannot figure out how to reconnect. I tried checking each wire with a hot jumper but the lights would come on and then go off. The lights from the truck are all functioning as should, but the RV wiring doesnt seem to work. The RV wiring did not get pulled out just the 7 way. Please help!

asked by: William S

Expert Reply:

We can help you get your RV's 7-way wiring sorted out.

The easiest way to go is to replace the whole junction box with etrailer # HS381-9000 since this has a pre-wired 7-way. This means you only have to make the RV side connections. The wire gauge will be thicker for the 12V (black) and ground (white) wires which gets a few of those out of the way right off the bat.

It sounds like you already tried testing the functions on the RV wires. This process is usually pretty straightforward. You can use set of jumper cables and two short lengths of wire to first make a battery ground connection to the trailer frame ( a clean bare metal spot is best) and then, one by one, apply the +12V wire to each wire on the trailer to see what function becomes active.

The linked article on wiring and the photo of a trailer side plug show the usual RV 7-way connector's circuit arrangement for each function. Having a helper on hand to watch the trailer lights
as they activate will make this process easier.

expert reply by: Adam R