Why Would Trailer Wiring have Two White and Brown Wires

Updated 03/22/2022 | Published 03/20/2022

Question:

Hello, I bought the A20WB wiring harness to replace the harness on my encloses trailer that rodents eat up. They ate away at the original harness where it went into the floor. I ordered dthis harness because it looked like what the original did. However when I went to start making connections I realized there was a fifth qhite wire? The tail lights are LED. The original had yellow, brown and black, green wires. The one I ordered from you all had a white wire that grounds to the tongue. When I went to connect to the lights in the trailer, there was a white wire that seemed to go to both of the LED lights. When I connected all the wires except for the white, only the running lights work. No tail, turn signals, or brakes. Do I need to extend the white ground from the tongue of the new wiring harness to go to the white wire on the inside of the trailer? I cant see how it was originally because apparently those rodent were hungry and they didnt leave me much to work with.

asked by: Brian Q

Expert Reply:

It's not uncommon for trailer wiring to have more than one wire for the same circuit for the ground and running light circuit. For the running light circuit (brown wire) this is to allow you an easier way to run the circuit to either side of the trailer. For the ground circuit (white wire) it's to allow for making more ground circuit connections easier since all of the circuits have to be grounded. So if your trailer has two ground wires you could run them both together and then to the white wire of the # A20WB.

expert reply by: Jameson C