Troubleshooting Curt 4-Pole Trailer Wiring Harness Installation in 2016 Kia Sedona

Question:

I just recently traded in my Chevy Equinox for a 2016 Kia Sedona I put a new trailer hitch on the Sedona and bought the proper wiring package for it everything fit in there properly and I checked each individual part with a light and everything works fine blinkers running lights brake lights but then when I plug it into the trailer I get nothing but running lights no brake lights no turn signals but it works fine on my old vehicle what could be my issue

asked by: Dale S

Expert Reply:

Thank you for your recent hitch and wiring harness purchase. I am sorry that Curt 4-pole wiring harness C56151 is giving you trouble in your 2016 Kia Sedona, which is intended for vehicles with the tow package. We're glad to help you troubleshoot.

It sounds like you applied a circuit tester like # PTW2993 to the pins on the 4-pole after you competed the installation. We know the harness is getting power since it is able to deliver the running light signal to your trailer. This means the fuse is okay. If all the light signals are present on the 4-pole connector when you test, but just not when the trailer is connected, then it sounds like the harness is okay but there could be an issue on the trailer side.

First, make sure that the trailer's wiring harness ground wire is securely attached to a clean bare metal point on the trailer frame. A bad ground may let some light functions operate properly while others may not. You can sand off any rust or paint at the grounding point to provide good metal-to-metal contact or you can relocate that ground wire to a new clean spot if you prefer. Also check the trailer connector for signs of corrosion or discoloration and clean if needed. Sometimes a connector may have an intermittent internal connection problem that only shows up when it is plugged in.

If that does not correct the problem then check the two vehicle side connectors on the harness that plug in under the left rear wheel well. Inspect the contact pins inside each connector (on both harness and vehicle) looking for bent pins, corrosion or anything else like trapped dirt or water that could interfere with signal transmission.

You can also apply your tester to the 4 wires leading into the black harness plug from the car. With the harness plugged in test the green and yellow wires (one at a time) while your helper activates the right turn/brake and left turn/brake. If there are no signals entering the harness from the car, then the vehicle may be missing a relay or fuse related to the tow package.

expert reply by: Adam R