Trailer Plug is a 4-Way Flat But there are 6 Wires

Updated 05/24/2024 | Published 10/06/2018

Question:

My trailer has a white green yellow and brown my trailer lights have a white green yellow and to Browns what do I do

asked by: Paul

Expert Reply:

It sounds like your trailer had a wishbone harness and/or could have multiple ground wires. On a 4-Way trailer end, the one covered pin is the ground. Next to that is the running light pin. The running light pin on some connectors will have more than 1 wire coming out. One of those wires is for the driver's side running lights and the other is for the passenger's side running lights. So it could be a situation like that.

On the actual trailer lights look at where the wires go into the lights. The functions might be labeled on the light housing.

Usually, white wires are grounds, green is right turn signal/brake lights, yellow is left turn signal/brake lights, and brown is running lights.

If you'd like you can snap some pictures of what you're seeing and email them to me.

expert reply by: Michael H

Micheal C.

2/11/2020

I have a trailer with a yellow, yellow brown,green, green with brown,brown wire, white how do wire to 4 wire plug.

Jacob H.

2/12/2020

It sounds like your trailer has a wishbone harness. A wishbone harness splits the running light circuit at the connector so you do not have to run a jumper from one side of the trailer to the other side. On a wishbone 4-Way connector the white wire is ground, yellow is left turn signal, yellow/brown is left side running lights, green is right turn signal, and green/brown is right side running lights. If there is a 5th pin then this most likely goes to an electric reverse lockout solenoid for hydraulic brakes, typically found on boat trailers. It could also be electric brake if the trailer is not a boat trailer but is still equipped with brakes. If the trailer is not equipped with breaks at all then it is most likely a reverse light signal. Lastly, it could be a 12V power wire run for any accessories that might be on the trailer. To wire up your trailer you will need # 20036. I have linked a helpful article to help you get it wired up correctly.

Helpful Links

faq-wiring.aspx

Wiring/Tow-Ready/20036.html

David B.

3/27/2021

Problem: 6 wires coming from trailer, 4 wires from vehicle pin connector. Solution : Simply connect colors together, All brown together with brown, and all white together with white. Green with green, yellow with yellow. Reason: Two ground (white) one for each side. Marker and tail lights (brown) one for each side. (Green) right stop and turn (Yellow) left stop and turn. On some aluminum trailers, there is no visible ground on the tongue. The ground wire runs to the individual lights, thus the need for one on each side. Source : School of Hard Knocks

Kef G.

3/30/2021

@DavidB While it's likely in your situation that matching the colors will work out, it's always important to remember that this isn't always the case. That's why we recommend verifying the functions for each wire and going that route. Sometimes the colors don't end up matching since many manufacturers like to use their own color schemes.