What are the Functions of Trailer Light Green, Yellow, and Brown Wires
Updated 06/03/2025 | Published 06/23/2012
Question:
Installing turn lights to a 4 flat trailer. Old original lights have 3 leads, Red, black and green. New Right side wires are Green and brown. New left side wires are yellow and brown. Which colors should be spliced together?
asked by: William I
Expert Reply:
Normally, the green wire on the right side carries right turn signal and brake light functions and the brown wire carries running light functions. On the left side, the yellow wire carries left turn and brake lights and the brown wire again carries the running lights. With only 2 wires, these lights must ground through the mounting studs.
Make sure to wire in the new lights by function to the existing trailer wiring and not by color.
Roger
6/1/2025
Appreciate your help! I’m wiring My boat trailer lights to the usual flat four plug I understand the color arrangements green yellow brown and white. However one wire is green on one side and brown on the other side. Where is it supposed to hook into? I have it with the green it’s that correct? Or brown? Or is it meant for a five flat? Thanks. Roger C ???
Robin H.
6/3/2025
Product Page this Question was Asked From
Hopkins Wiring Harness with 5-Pole Flat Trailer Connector - Vehicle End - 5' Long
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- No Converter
- Universal Fit
- 5 Flat
- Plug and Lead
- Splice-In
- Hopkins
more information >
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on Custom Fit Vehicle Wiring
Line C.
5/24/2020
Hi! I only have 3 wires on the trailer (brown, white, green) and 4 on my Chevy van.. extra red.. How do I plug it in ? Thanks!