Troubleshooting Right Side Trailer Lights Not Working  

Question:

Expert Reply:

If just the right side trailer lights aren't working then the first thing I recommend doing is using a circuit tester like # PTW2979 on the tow vehicle side connector. Test the right side turn/brake circuit pin with that function activated on the vehicle to see if you get power.

This will let you quickly determine which side the issue is on (vehicle or trailer) so you don't have to waste time troubleshooting an area that's good to go. If you do get power then you know the problem is on the trailer. If you don't get power the issue is somewhere on the tow vehicle.

If you do get power at the connector, first visually inspect the trailer side connector for any debris/corrosion that might be built up inside and around the pins, cleaning out as needed. Then try to trace the right side wiring as far as you can from the back of the connector to the rear of the trailer where they connect to the light assembly. Look for any damaged, pinched, or exposed areas of wiring that need to be replaced. Make sure the light assembly itself is securely grounded to a clean, bare metal surface (whether it uses a dedicated ground wire or simply grounds through its mounting hardware). If all of this is good it will be worth it to make sure the light itself is in good working order. You can try applying 12V power directly to it to make sure it's not just a bulb that needs to be replaced.

If you didn't get power at the tow vehicle connector then it could be a blown fuse under the hood (if you have factory trailer wiring). Check your owner's manual for the appropriate fuse locations and replace if needed. Make sure the main harness ground is securely attached to the frame.

If this doesn't resolve the issue please let me know and we can continue to troubleshoot.

expert reply by: Chris R

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