Only One Trailer Brake Light Does Not Work, All Other Trailer Lights Work

Updated 06/10/2015 | Published 06/08/2015

Question:

My travel trailer has LED style tail lights without separate bulbs for the turn signals. both blinkers work but only one side comes on with brakes. also hazards work fine. what might cause this?

asked by: Travis B

Expert Reply:

Usually when all other lighting functions work except for one it indicates a bad ground. Ground problems normally show up when there is more draw on a system such as the constant draw of the brake lights.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

expert reply by: Michael H