Troubleshooting Wishbone Wiring On Trailer

Question:

You have answered this question but it didnt work as planned for myself. I connected the white with the white, the green with green, the yellow with yellow, and the yellow with brown stripe along with the green with brown stripe to the brown wire. The turn signals work, the lights come on when I turn truck lights on, the turn signals work much brighter when the lights are on. The brake lights dont work and they cancel out the lights being on. The flashers only work when the truck headlights are on and when the brakes are applied it cancels them out and no lights are on at that point. Hope you understand. So lights are on with truck headlights on, blinkers work and are the only thing that work when the brake is applied, all else is cancelled out and there is no brake lights. Not sure if there is another way to hook these wires up or not?

asked by: D

Expert Reply:

It sounds like you have attached the wiring on your trailer correctly. You may want to check the ground to make sure it is attached to a clean bare metal area on the trailer. Also make sure the lights on the trailer are properly attached. Many lights are grounded through the mounting hardware.

You will want to check the trailer connector on your truck to make sure all of the functions are working on the appropriate wires. You can use a circuit tester like part # PTW2993.

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 attached a helpful article on trailer wiring you can check out.

expert reply by: Jeffrey L