Question:
Y is ther a light green and a dark green wire coming off the truck harness at the trailer feed.
asked by: Scott
Expert Reply:
The color of wires on a trailer wiring harness can be different colors so we always recommend using a circuit tester like part # PTW2993 to test the wires on a harness by function instead of color.
A typical 4-wire harness will use White for ground, Brown for running lights, Yellow for left turn/brake, and green for right turn/brake.
The best way to determine what the functions are is to have someone sit in the driver seat and run through the functions while using the circuit tester.