Troubleshooting # 118418 T-One Vehicle Harness Installed on Saturn Vue

Question:

Hi, I purchased this harness awhile back. Its been working great until two weeks ago when it started to show some strange behavior with the passenger side lights. The right turn signal no longer works at all. With the taillights on, the trailer bulb WILL light up but only on the brighter brake filament. If you step on the brakes with the taillights on, there is no change in brightness because the brake light is already on steady. If you step on the brakes with the taillights OFF, the brake light will work properly. I experience similar issues when using a tester on the harness. For troubleshooting so far, I have: removed the ground screw, cleaned and sanded and retightened. I have checked and cleaned all connections behind the taillights. I have tried different bulbs and even switched over the entire light assembly from the other side of the trailer. By the way, all of the lights on the vehicle are working properly, even with the trailer plugged-in. I believe that the converter or another part of this harness is faulty. It carries a 1-year warranty and Id like to see about getting it replaced. Thank you for your help.

asked by: Dan M

Expert Reply:

Whenever trailer lights exhibit strange behavior, its typically a result of a poor ground connection. It sounds like you have done a wonderful job of troubleshooting up to this point. The only thing it appears you have not checked is the grounding point on the vehicle side of the equation, where you have the ground wire for the converter attached.

Another quick method of troubleshooting is trying the trailer on a different vehicle or the vehicle with a different trailer (if possible). This will tell you right off the bat where the problem lies.

If checking the converter box ground on the vehicle does not fix the problem, you can test the converter box itself. Activate the right turn signal and use a circuit tester like part # PTW2993 on the green wire on the INPUT side of the converter box. The tester should blink along with the turn signal. Then, test the green wire on the OUTPUT side of the box. If you have signal entering, but not leaving the box the converter is indeed bad and would need to be replaced. At that point, you would want to call our Customer Service folks for instructions on how to proceed.

I have linked you to our FAQ page on trailer wiring troubleshooting.

expert reply by: Mike L