Troubleshooting Dim Lights on Trailer

Question:

only part of the lights are dim could that still be a weak ground

asked by: Douglas B

Expert Reply:

Absolutely. An insufficient ground connection can make trailer lights do all sorts of crazy things. Checking and fixing the grounds is very simple. The main ground will be located on the trailer tongue. Just follow the white wire from the trailer connector to where it connects to the trailer tongue using a bolt of self tapping screw. Make sure that connection is tight and not corroded. You can make this connection bulletproof by disconnecting the ground connection and using some sandpaper to take a dime-sized area around the screw or bolt hole down to bare metal. When you reattach the ground screw or bolt, place a star washer between the ring terminal and the trailer tongue. This will bite into the trailer tongue and make a great connection. Finally, give the area a quick shot of rust inhibiting spray pain like Rust Oleum to protect it.

Each trailer lamp picks up its ground connection either via its direct contact to the trailer frame or via a ground wire attached to the trailer frame. Make sure these connections are also tight and free of corrosion.

Once you get your grounds all cleaned up, you should be good to go. You might also consider switching over to LED trailer lamps at some point. LED's use a fraction of the power of incandescents, they last much much longer and they are quite a bit brighter.

I've linked to some trailer wiring articles that you might find helpful.

expert reply by: Mike L