Troubleshooting Trailer Taillight Running Lights Not Functioning 2013 Honda CR-V

Question:

I installed the wiring harness a little over a year ago and everything went well, all the circuits worked fine during our travels last year. Today I hitched up the trailer and when checking the lights I found that the tail lights on the trailer do not work. Turn signal and brake lights are fine, but no tail lights. The CRV lights work fine. Before I open up the panels to check the harness can you advise what is the likely problem that I should look for and a fix?

asked by: Daniel E

Expert Reply:

First thing you should do at this point is test the 4-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. A lot of times the problem you described is due to weak grounds on the taillight assemblies.

Make sure that the trailer side connector 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.

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