Trailer Brake Wiring Diagram 4 Pin. It gets complicated when you have trailers with more cables, and in this case, you need an adapter to make the connections. Offroaders Staff Editor Trailer & Towing.
Learn all about trailer wiring at HowStuffWorks. Cut the four-pin plug off of the trailer harness. This is where it gets a bit tricky.
There should be a common color for both the tail lights.
But if you only need the brake lights and taillights hooked up, why would you ever need more than four pins?
Common trailer wiring faults & some helpful wiring diagrams. Trailers that use this are usually fairly light weight and don't have brakes or other power. Cut the four-pin plug off of the trailer harness.