Troubleshooting 2011 Kia Sorento 4-Way Tail and Running Lights Not Working

Question:

Hi, I installed a 4 pin electrical connector/harness on a 2011 Kia Sorento, but wasnt able to get trailer marker and tail lights to come on, but they worked as turn signals/flashers and brake lights. I tried another harness with the same results. I tested and got ~12 volts at connector for the lights, when Kia parking lights were turned on. U-Haul electrical tester also showed the harness/connector as good. How can it test good and have working flashers and brake lights, but no working marker/tail lights? I even tested it on another trailer with known good tail/marker lights, and those same lights wouldnt come on on the other trailer either. Is there too much voltage/amp draw that the Kia couldnt compensate for the trailer lights. I tested the same U-Haul trailer with my Jeep and was able to get all the lights to come on correctly. Any advice is appreciated.

asked by: Abe G

Expert Reply:

This is a tough one. It is safe to say we can rule out the trailer since you plugged it into your Jeep and everything worked. I would also say you ruled out any issues with the aftermarket wiring harness. Since you have installed two different wiring harnesses and got the same result with both it is likely a problem with your 2011 Sorento factory wiring.

The trailer lights aren't going to be pulling too much power, especially on something small like a U-Haul trailer. The wiring harness also has a powered converter so there won't be any real strain on the vehicle wiring. That doesn't mean it is absolutely impossible but I don't think that is something you will be fixing on your own.

If you can find the ground for the factory wiring I would double check that since bad grounds are known to create strange issues like what you have encountered. Outside of the ground I would try taking it to the dealer and have them check it out. It would probably be a good idea to show them what it is doing with the trailer so they don't just test it like you did and say nothing is wrong.

expert reply by: Robin H