Installing Brown Running Light Wire on Trailer

Updated 11/24/2017 | Published 11/23/2017

Question:

Hi guys, I am wiring a small trailer for my friend, and Im using a 4 way connection plug. So now I have wired the whole trailer but before I hook up the 4 way harness to my wires I wanted to test them with a battery pack so what I did is ground my battery pack to the trailer and I than proceed to test each wires separately. I touch the yellow one and the left light came on, which should be ok, than I touch the green wire and the right light came on which is ok too, but when I touch the brown wire all the lights came on side markers too but for some reason the left one didnt ?? so I guess what Im asking, is this OK still I know once the 4 way plug is hook up to a car or truck that power might go to more than one wire at the time but for testing purpose only if I want to test the trailer by testing one wire at the time are my result OK ? Im wiring this trailer for a friend so I dont have a car to test it right now.

asked by: Claude P

Expert Reply:

When testing the brown wire on your trailer, all of the tail lights on the trailer should be activated. Since you are using a standard 4-wire harness on the trailer, you will need to make sure that you are using jumper wires to provide running light functions for both sides of the trailer. The single brown wire will go back from the 4-Way connector on one side of the trailer, but will then need to be fed to the lights on the other side as well.

I have attached a wiring diagram that clarifies this. Take note of how the brown wire is run down to the left rear of the trailer, and then back across to the other tail light with jumper wire.

expert reply by: Chris R