How to Wire in New Trailer Lights When Wire Colors are Non-Standard

Question:

My truck has a 7 blade hook up. The older camper we bought recently had brake lights by no turn signal. We bought replacement lights that were wired for turn signal and brakes. But when I took the old lights off I have 2 white wires, 2 green wires and a black wire coming out of the trailer. On my new lights I have 2 white, 1 green, 1 red, and 1 black wire. How am I supposed to wire this together?

asked by: Caleb R

Expert Reply:

You'll have to use a circuit tester like part # PTW2993 to test all of the wires on your trailer when you apply the various turn/brake signals so that you can identify what each wire carries. And then you can use a jumper wire from a 12 volt battery to each of the wires on the new light to determine the function of each. Most likely white is ground though just from looking at the picture.

Aside from that there's no way to for sure know what the color wires all carry function wise.

expert reply by: Jameson C