Troubleshooting Trailer Running Light Circuit that Stays On all the Time


hello, I purchased the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56040. I installed it in my car and I recently noticed that my trailer lights tail and license plate lamp stay illuminated when the car is turned on and the harness is plugged in. I checked with my wifes car and the lights of the trailer turn off with the car. Is there something wrong with the wiring box system?


Expert Reply:

If you have LED taillights on your trailer and they are only partially illuminating then that is normal. If you have incandescent bulbs on your trailer and the light are fully illuminating then the problem is most likely the trailer harness on the vehicle.

Use a circuit tester to test the pin on the 4-way for the brown wire to see if there is voltage there at al times. Now test the brown wire going in to the converter box for voltage as well. If there isn't voltage going into the box on the brown wire but there is coming out then the box has shorted out and needs replacing.

I attached a help article on troubleshooting 4-ways for you to check out as well.

expert reply by:
Jameson C

Ask The Experts a Question >>

Products Referenced in This Question

Product Page this Question was Asked From

Similar Expert Q&A Pages

See More Q&A Expert Answers >>