Identifying Circuits on Possible Wishbone Trailer Connector

Question:

i have a 4 prong plug with 5wires coming out of it. On right side of trailer i have 2 greens with a brown connected to them, on left i have yellow and brown and a white common how do i wire these together correctly?

asked by: Mike

Expert Reply:

What you are describing sounds like a wishbone harness. A wishbone harness splits the running light circuit into two wires coming directly out of the 4-pole connector.Instead of a single brown wire carrying the running light circuit, you would have a brown/green wire for running lights on the right side of the trailer and a brown/yellow wire for left side running lights. You would also have a yellow wire carrying the left turn/brake light circuit, a green wire for right turn and brake, and a white wire for ground.

To confirm, you can always use a car battery to apply 12 volts to each circuit on the trailer to see which lamps each circuit illuminates.

I have linked you to our Trailer Wiring FAQ article that you might find helpful.

expert reply by: Mike L