Re-Wiring Trailer with 4-Pole Flat Wiring

Question:

The wishbone wiring on my utility wire consists of 4 wires which are solid green, solid yellow, green/brown and yellow brown. No white ground wire exists. The original plug end on my trailer is gone and I need to install a new one. My issue is I have been unable to a find a plug end with wiring that mirrors the color combination on my trailer wiring. They all seem to have wiring of the solid green/yellow/brown and white variety. Is there a way to use the solid 4 color plug end with the color combination wiring on my utility trailer? If so what would serve as a ground wire? Any help your are able to provide would be appreciated. Thanks.

asked by: Gary E

Expert Reply:

Wire colors in trailer wiring sometimes follow convention, such as a white wire most often being used for ground and a brown wire being used for running lights. But there is never a guarantee that the "usual" wire color for any given function is used on any particular trailer. In typical 4-pole wiring the wire color convention is: white is ground, brown is running lights, yellow is left stop/turn and green is right stop/turn. This wiring scheme information is included in the linked help article on trailer wiring.

The best way to know what function a trailer wire handles is to apply 12V power from a battery so you can see which function is activated. But since you seem not to have a ground wire you might simply prefer to start over and replace your trailer wiring.

The best way to do this is with a junction box # 38656, ring terminals # 44-5310A, a 4-pole wring harness like # A35W42B and bonded wire # 16-4B-1 which will run from the junction box to the lights.

expert reply by: Adam R