Is there an Adapter to Go From Semi Style 7-Way to RV Style 7-Way Trailer Connector

Updated 07/30/2018 | Published 07/28/2018

Question:

You have instructions on how to do this with three parts including a converter on another answer page I am just wondering it would seem somebody would make this adapter pre-made. Do you know if there is one?

asked by: Dyrell H

Expert Reply:

Because the functions on a semi 7-Way connector are different than those in the RV industry a regular adapter would not work. Some of the circuits have to be combined so a converter is needed. It would actually be easier to just add an RV style 7-Way on the semi rather than making an adapter as described in the question you referenced.

If your semi has combined brake lights and turn signals on the same circuits then you would just need a vehicle side 7-Way such as # 50-87-009 and wire it in by function. On this harness green is for running lights, red for left turn signal and brake lights, yellow is auxiliary power or reverse lights, brown is right turn signal and brake lights, white wire is the ground, black is the 12 volt hot lead, and blue is output to electric brakes from a brake controller.

If the turn signals and brake lights have separate bulbs on your semi then you would first need to convert the separate circuits to combined using a converter such as # 119178 (you would cut the 4-Way end off and hardwire it to the 7-Way by function (white is ground, green is right turn/brake, yellow is left turn/brake, brown is running lights).

expert reply by: Michael H