What Does My Red and Black Wire Do on My Trailer Lighting?

Question:

I am replacing my boat trailer lights. the lights have only a black and red wire coming out of them. I am using a flat four wire harness. With the brown going to both sides , green going to the right for turn and brake, and the yellow going to the left for turn and brake. What is the connection sequence to the trailer wires.

asked by: Larry A

Expert Reply:

I have an answer for you. You are correct in your wiring for your flat four-pole harness. When it comes to the black and red wire coming out of your replacement lights, there is really no way for sure to know what the functions are of those two wires without knowing the specific model of lights that you have. Typically, the black is ground and the red is power. With that being said, I suggest inputting power to each of those wires individually to see what activates. Once you know the function of the individual wires, you can splice accordingly to the trailer wires.

expert reply by: Bob C