4-Pole Trailer Wiring Functions & Wiring Installation for Optronics Oval LED Trailer Light STL78RB

Updated 05/08/2018 | Published 05/06/2018

Question:

STL78RB I was going to purchase two of these for a coleman camper. I have a 2017 Tacoma with tow package. I have the 7 pin and 4 pin options. Could i just use a 4 pin for this application when hooking to tacoma just not using the 4th pin for marker lights?? Didnt know if i need the 3 pin adaptor. Thank You very much !!!!

asked by: Bill B

Expert Reply:

In standard 4-pole trailer wiring there are actually three active lighting circuits plus a ground. The tail light (or running light) function is carried on the (usually brown) wire that is next to the ground pin. Please refer to the linked photo of a trailer-side 4-pole connector that shows these circuit/function assignments.

The next pin over, the one for the yellow wire, typically carries the LEFT stop and turn light functions which are combined onto this one wire; and the RIGHT stop and turn light functions are on the green wire. You need all three of these lighting functions active for towing your Coleman camper trailer. If the trailer has electric brakes then you need an additional circuit for that trailer brake function to work, either a 5-pole, 6-way or your factory-installed 7-way wiring setup. You can also refer to the linked article on trailer wiring for more information.

The Optronics Oval LED Trailer Light # STL78RB uses a 3-wire hook-up. The white wire is ground, the red wire handles the stop and turn functions and the black wire handles the running light circuit.

expert reply by: Adam R