How To Wire Trailer With Red, Green, Yellow, And Brown Wires

Updated 08/09/2021 | Published 08/07/2021

Question:

My trailer wiring has a red green yellow and brown wire, my harness connection has a yellow green and two browns. What goes where?

asked by: Tom B

Expert Reply:

It sounds like you have a 4 way flat wiring setup. The yellow wires (left turn/stop) will connect to each other, just as the green wires (right turn/stop) will connect to each other. The brown wire (taillight/side marker) should connect to the other two brown wires. By process of elimination, your red wire looks to be your ground wire which would normally attach to the white wire for ground.

Keep in mind, there is not a definite standard for color coding when it comes to trailers, so an absolute sure way of knowing the function of each wire is to use a tester such as # PTW2992. You can have someone test each light function on your vehicle while you check to see which wire gets 12v, then match the wires up accordingly to your trailer.

expert reply by: Andrew N