Trailer Running Lights Stopped Working with 2015 Kia Sorento

Question:

My trailer lights were working and then the running lights stopped working. My turn signals and brake lights still work. I have a 2015 kia Sorento. I bought the curt harness from etrailer.com. can you help?

asked by: Lonnie R

Expert Reply:

I will be happy to help figure out the problem with the wiring harness on your 2015 Kia Sorento. The first step is to determine where the problem is. To do this some testing is required using a circuit tester such as # PTW2993. Or if you have a meter that will work too.

With the trailer disconnected you can test the wiring harness. First, check the brown wire that goes into the converter box from the vehicle. This is the running light circuit. If it does not show power with the vehicle headlights on then check the connection of that brown wire to the vehicle wire. It may just need a new connection to the vehicle wire.

If everything is connected properly and there is still no power on that wire then the likely cause is a blown vehicle running light fuse. If there is power on the brown wire then we can move on to the next step.

The next step is testing the wiring coming out of the converter to the 4-Way plug. The brown wire should have power when the vehicle headlights are on. If it does not then something is wrong inside the converter and the wiring harness will need to be replaced. For the i4 cylinder motor on models without the factory tow package I recommend # HM11143820 which plugs in line with the vehicle tail light wiring.

But if everything is working on the vehicle side trailer connector then the issue is on the trailer; likely a bad ground. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light but can show up any time.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.