Troubleshooting Trailer Lights not Working After Harness Install

Published 06/21/2017

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(543)

$49.26

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(198)

$41.94

Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(5)

$65.84

Hook Probe Circuit Tester

(60)

$12.27

Question:

Installed trailer wiring harness and the lights on trailer still don't work. Any suggestions? Thanks.

asked by: Bob

Expert Reply:

There are a number of steps for you to take to figure out exactly why the lights on your trailer are not working. You did not specify the harness you used, but for a 2007 Honda Odyssey, there are three fits, the T-One # 118438, Curt # C56161, and Hopkins # HM11143115.

To start, we'll isolate the problem to either the trailer or vehicle. You can do this by using a circuit tester such as # PTW2993 to check the functions of the 4-way plug while somebody else engages them (brake, turn signal, taillights). If there is an issue, check for a blown fuse. However, if all the functions are right, this will tell us the wiring harness is fine and the problem is on the trailer side.

You will need to check to ensure the wires are connected in the right locations, and that the ground wire is attached to the trailer frame in a clean surface free of any paint, dirt or rust. I have linked an article called "Troubleshooting 4 and 5-Way Wiring Installations" you will want to follow, as well as an article on trailer wiring which you will want to look over.

expert reply by: Kyle S