What are the Functions of the Wires on a Gooseneck Trailer with 7 Wires

Question:

Left lights plug into truck pulled out at goose neck of trailor 7 wires black blue brown yellow green red white

asked by: Jim A

Expert Reply:

There isn't a standard for trailer wiring color but the likely functions of those wires are red for left turn/brake lights, yellow for reverse lights, brown for right turn and brake lights, green for running lights, black for 12 volt power, blue for output to trailer brakes, and white for ground.

On the trailer side you could either trace each wire back to determine the function of each or you could use a separate 12 volt battery and connect each wire, one at a time, to the positive terminal to determine what turns on. I have included a link to our help article that covers trailer wiring and the various types of connectors.

expert reply by: Michael H