How to Upgrade Trailer from 6-Way to 7-Way RV-Type Wiring for Lighting and 12V Power Functions

Question:

I have a 7 way connector on my 4Runner so I have a 7 wire electrical cord but Im putting a 6 way on the other end because my trailer only has 6 wires so which wire do I not use ? Right now I have it so the black wire isnt connected at all on the 6 way side but I was told that with the old cord it would charge the battery the old cord was a 7 way with only 6 wires attached to a 6 way square on the other end please help I have it all hooked up and I have turn signals hazards brake lights and electric brake but I want to see will it charge my batter and how would I check to see if its charging my battery

asked by: Josh S

Expert Reply:

The best way to match up your different vehicle and trailer wiring is to install a 7-way on the trailer.
It is much easier to work on a trailer's wiring than a vehicle's. And doing this avoids adapters that can often end up being a pain in the long run.

A standard RV-type 7-way trailer setup includes all the lighting signals for the trailer plus a brake circuit for the trailer's brakes, a reverse light circuit for trailers that have clear backup lights and a 12V trailer power circuit that can help maintain a charged trailer battery while you drive. You can refer to the linked photo for illustration of the functions and pin assignments on an RV 7-way.

I suggest you use a 7-way trailer plug and wiring junction box, parts # H20046 and # 38656, along with ring terminals like # 44-5310A. All you need to do is apply 12V power to each trailer wire to see what function it has and then connect up all the wires according to the photo. This will ensure all your lighting and 12V power functions operate properly.

expert reply by: Adam R