Troubleshooting No Running Lights on Tractor Supply Trailer

Question:

I have brake lights and turn signal lights but no clearance lights

asked by: James C

Helpful Expert Reply:

There are numerous possible causes as to why the clearance/running lights aren't working on your trailer, and the root of the issue could be on the trailer or on your tow vehicle. Because of this the first thing I recommend doing is using a circuit tester like # PTW2993 on the vehicle-side connector to test the running lights circuit when you have them powered on.

If you don't get power on the tester you know the issue is somewhere on the vehicle. If you do show power then the problem is somewhere on the trailer.

If you didn't get power on the tester, I recommend checking your vehicle's owner's manual for any trailer related fuses under the hood. If your vehicle has some kind of factory tow package, there's likely a fuse dedicated to the trailer running light circuit. Check to make sure it's present and in good condition, replacing as needed.

If the fuses are good or you don't have a tow package, inspect the wiring connector itself for any debris or corrosion that needs to be cleaned out. Inspect any wiring you can access going back from the running lights circuit pin and look for any pinched or damaged portions that need to be replaced. Make sure it's still securely attached to the running lights circuit wire on the vehicle.

If you did show power when testing the vehicle's connector then you can focus on the trailer. Inspect its connector for debris/corrosion and try and trace the running lights wire down the trailer, again looking for anything that needs to be repaired/replaced. Make sure the main harness ground is securely attached to a clean, bare piece of metal on the frame. Also do this for the individual light assemblies at the back of the trailer, whether they use a dedicated wire or ground through their mounting hardware.

If you still aren't able to resolve the issue please let me know and we can continue troubleshooting. I have attached a great article on common trailer light issues below that you can also check out.

expert reply by: Chris R