Wire Functions for an ID Light Bar at the Top Center of a Trailer
Question:
I have a old LED slimline tail light that burned out on my horse trailer across the top of the back of the trailer, it has 4 wires on it, white, green, yellow and brown. All the new lights I see for a replacement are 3 wire, how do I put it back together right?
asked by: Sandy
Expert Reply:
On trailer wiring the common wire functions are white for ground, green for right turn signal/brake light, yellow for left turn signal/brake light, and brown for running lights.
Usually the light at the top center at the back of the trailer is an ID light bar and it usually runs just off the running light circuit. It sounds like the one you have also is being used as a third brake light and might or might not flash with a turn signal on.
It is also possible that he replacements you have seen ground through the mounting hardware so they would only need 3 wires. But it depends on the color/function of each wire. If you can tell me which replacement(s) you are looking at and what functions the original light has (just running lights, just brake light, both, turn signals, etc) I can make some recommendations.
