Wiring New 3 Wire Light on Trailer to Replace 2 Wire Light

Updated 06/04/2024 | Published 07/27/2018

Question:

hi bought pair of led tail lights for older trailer called top brand of course out of business now. has normal 4 wire hook up back light has two wires brown and yellow on one side then brown and green on the other. my problem is the new lights come with three wires red black and green.cant return bought at yard sale, i think i know why they where selling them. thanks for any kind of help.

asked by: Joe

Expert Reply:

I can't be certain what the function for each of the wires are on your new trailer lights, but one of the three wires is likely for ground. Your old/existing trailer lights grounded through their mounting hardware, which is why they only had two wires and didn't need a third for a ground connection.

If you turn the light assembly over, the functions for each wire should hopefully labeled somewhere. The most likely scenario is that the black wire is for ground, the green wire is for stop/turn lights, and the red wire is for running lights.

expert reply by: Chris R