Left Side Trailer Lights Don't Work When Towing with 2003 Honda Pilot

Question:

Hi, I recently bought a trailer harness for my Pilot, installed it and am having lighting issues on my trailer. My boat trailer works fine on a different vehicle, but not this one. Im assuming ground issues. The entire right side of the trailer works great, but the left side brakes only work some of the time and the blinker is very dim. All the grounds on the trailer each trailer light are attached to the trailer frame. The ground wire on the vehicle side is black when I strip it back corroded?. If it was a ground issue, wouldnt all the lights not be working, not just the left side? Would it help if I take the vehicle side ground, strip it, and mount it to the frame of the vehicle somewhere? All the lights on my vehicle work great as well. Helppppp

asked by: Cory

Helpful Expert Reply:

I agree that it sounds like you have a ground issue. Ground problems often present themselves through strange wiring issues. Having a ground issue may not cause all of the trailer lights not to work. It is not uncommon for only one side of the trailer lights to not work, or the lights to dim when the blinker is used, when there is a ground issue.

When stripped back, a black ground wire would more likely indicated that it has somehow been fried, not corroded. Corrosion usually presents a white or blueish-green substance.

Since the trailer wiring for your vehicle is a plug-and-play style connector, I would not recommend cutting the trailer wiring harness or your vehicle factory wiring to attach the ground wire to the vehicle frame.

I recommend your next step be testing the vehicle side connector at the 12V wire to ensure that you have 11-12 volts of power at the connector. If you are not getting the correct voltage at the connector, then we can be sure that the issue is on the vehicle. Since the trailer wiring connector plugs into your vehicle's factory wiring harness, we recommend taking it to your local Honda dealer and having the vehicle wiring checked out by a certified automotive mechanic.

expert reply by: Victoria B