Troubleshooting Running Lights Not Working On Two Trailers Towed by a 2006 Jeep Commander

Question:

I have a 2006 Jeep Commander and have no running lights on either my utility trlr. or boat trlr. All of the wires are hot to the trlr. lights. Could this be a ground problem?

asked by: Greg W

Expert Reply:

This could definitely be a ground problem. Without a proper ground, the circuit cannot be completed which can cause light failure and/or malfunction. You will also want to make sure you are using the correct wiring harness. For a 2006 Jeep Commander with no factory package, you will need to use Tow Ready Custom Fit Vehicle Wiring, # 118408, instructions linked below. With a tow package, you would use Tow Ready Custom Fit Vehicle Wiring, # 118381. I have included a link to the installation details below.

With the correct harness installed, you can check the 4-Way like you have done. Make sure that the functions are working properly using a circuit tester like # PTW2993. If everything is working as it should, I would check the grounds on the trailers. Make sure they are attached to a clean and corrosion free bare metal surface. You can also check the grounds at the trailer taillights. Trailer lights usually ground through the mounting studs if an obvious ground wire is not present. They will also need to be attached to a clean and corrosion free bare metal surface.

After checking and fixing any bad grounds, you can also make sure the vehicle and trailer side 4-Way connectors are clean and free of corrosion. Finally, if the trailers have extra clearance lights on the running light circuit, it could be too much power draw on the system causing the lights not to work. In some cases, a vehicle will need a fuse or relay added to allow all of the functions for trailer wiring to work. I would check the fuse box/power distribution box to determine if a fuse is missing or blown that operates the lights.

expert reply by: Michael H