Trailer Left Brake Light Does Not Work with Trailer Connected to a 2003 Dodge Ram 1500  

Question:

Expert Reply:

Normally when all the lights work on a trailer except one or one side it is a ground issue. Ground problems usually show up when there is more of a draw on the system. The brake light is the brightest light requiring constant higher voltage than the other lights. A weak ground would cause the brake light not to light up.

Check the offending tail light for a good ground. Trailer lights usually ground through the mounting studs if there is not an obvious ground wire. In either case, the light needs to be ground to a clean and corrosion free bare metal surface. Also check the main trailer connector ground.

Another possible issue is that if you recently added a plastic license plate holder, that will cause a weak ground. You would need to use a metal license plate holder.

expert reply by: Michael H

0