Turn Signal Lights Work on Trailer but No Brake Lights

Question:

My trailer has only a white, yellow, green and brown wire, the 4 way flat trailer connector from power fist has a white, green, yellow wire and 2 brown wires. i connected yellow to yellow green to green and both browns to brown. When I connect i can get my turn signals to work but my brakes dont work but the brake lights come on the truck without pushing the breaks

asked by: Alice

Expert Reply:

I believe there is an issue on the vehicle's wiring as the connections you made are inline with the industry standard. Also, this would make sense because the stop and turn signals on a trailer with a 4-way connector are integrated into the same circuit so it sounds like the vehicle is only sending one of them or not combining them together. Can you please inform me of the year, make, and model of your tow vehicle in addition to what wiring harness you are using?

I would first start off by using a circuit tester and testing the pins on the vehicle side trailer connector. If the light only illuminates with the turn signals and not the brakes then you need to trace the turn/brake wire back to see which circuit it is tied into. If your vehicle has separate brake/turn signal lights then they will need to be combined with a converter like part # 119250KIT.

expert reply by: Conner L