What Functions Would Tail Lights with 4 Wires Use

Published 12/10/2019

Question:

I am putting all new lights on a 16ft. Car hauler including running new wire. My taillights are LED and have the reverse lights in them also. There are 4 wires coming out the back of the new taillights. Black, yellow, white, and red. White is my ground, yellow will be my R and L turn/brake lights. Not sure which is the other two for? Reverse and tail lights? Which is which? 4 wires off plug .

asked by: April

Expert Reply:

Thank you for the info! It sounds like your tail lights have the stop, turn, tail (running), and reverse functions similar to the Fusion LED Trailer Tail Light # STL211XRFHB. This means that one wire is for the stop and turn functions, one wire is for ground, one is for the tail/running function, and the other wire is for the reverse function.

The light that you sent in a picture of doesn't look like anything we have on our site so I'm not able to confirm what wires are for what functions but you can easily determine this by applying 12V power to each of the wires to see what part of the light actually lights up. If I had to guess I would think the follow:

White - Ground
Black - Running
Yellow - Stop/Turn
Red - Reverse

Obviously you'll want to test the lights to confirm this prior to making your connections more permanent.

expert reply by: Jon G