Troubleshooting Trailer Wiring Running Light Circuit Not Working on Truck

Question:

2010chevy Silverado seven pin for my camping tailer.yellow being my left turn.my wire colors of my truck are blue,black and red,dark grey,light grn,yellow ,brown ,white

asked by: Scott S

Expert Reply:

First thing you should do is check the pin of the 7-way on your truck that's in the 11:00 position for corrosion and/or dirt and clean as necessary. Next test the 7-way of the wiring harness with a circuit tester part # PTW2993 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached.

If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. That would mean that problem is either due to a ground issue or a short issue.

Make sure that the trailer side connector is 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.

If the problem is on the vehicle side then I would first recommend you double check how the harness is installed on your vehicle, make sure all of the connections are good and tight. You should check all towing related fuses and relays as well.

expert reply by: Jameson C