Determining Function of Trailer Wires with Unknown Colors

Question:

My old lights have yellow, for indicator red and brown for brake light and black for reverse. Which wires do I connect when the new lights are yellow, red, black, white, green and purple?

asked by: Jerimme W

Expert Reply:

The new lights are probably wired for yellow being reverse lights, red for left turn/stop, black for 12 volt power, white for ground, green for running lights, and purple maybe is brake output or right turn/stop.

With that said I would recommend you test to determine this for sure as it doesn't look like it's standard colors. You can do this by tracing the wires or by putting 12 volts on each circuit and seeing what activates. Ground will spark as you'd be creating a short so be aware of that.

expert reply by: Jameson C