Help Wiring New Trailer with 5 Wires Coming From Each Tail Light Assembly

Updated 09/21/2017 | Published 09/20/2017

Question:

Just bought a food concession trailer from China. Tail/Brake lights to the trailer are installed but 5 wires are coming out on both tail lights going into the trailer. My Chevy Colorado is wired to hook up. Cant remember if it is 4 way or 5 way harness. The distance from the tail lights to back of the truck is 16 feet. My question is what wiring would I need to be able to get power supply to my tail lights on my trailer.

asked by: William M

Helpful Expert Reply:

Since you have 5 wires coming from each tail light on your new trailer, the first thing I recommend doing is testing each wire for function. You can use a spare 12V battery to test each wire to see what they active on the tail light assemblies. Simply connect the battery's negative terminal to ground, then one by one, apply the positive terminal to each of the circuits.

Since it appears that your tail lights do have an amber light, I would expect 4 wires to be coming from each assembly (with white being for ground), but I am not sure what the 5th wire would be used for. This is why you will need to test them before proceeding.

You will then just need to run the wires up to the trailer tongue and to a 4-way harness like # A35W42B to connect with your tow vehicle. I have attached an article on trailer wiring that you might also find helpful.

expert reply by: Chris R