Troubleshooting New Trailer LED Side Markers Not Working

Published 01/11/2019

Question:

My lights on my trailer all worked until I changed the side marker lights to led. The old lights used a self tapping screw going though the trailer metal as a ground. The white ground wire for the trailer was also attached to one of these screws. When I tried to remove the old lights, 3 out of the 4 broke due to rust. So I drilled new mounting holes for the lights, and used bolts and nuts to secure the new leds. I made sure that the trailer where the nuts made contact was bare metal. So now the only thing that works are brake lights. Side marker lights dont work. Like I said everything worked before I made the switch to side marker led lights.

asked by: Brian A

Expert Reply:

The issue you are having still sounds like there might be a weak or bad ground on the new LED lights. The mix between them and the incandescent assemblies at the rear of the trailer should not be causing this problem so it has to be something specific with the new lights that were installed.

Many LED trailer lights feature a 2 wire design (one for ground and one for power) and don't actually use the mounting hardware for its ground like with your old assemblies. If the new lights have 2 wires make sure they are connected appropriately. The ground wire would just be attached to a bare metal surface on the trailer.

If this is not the case with the LEDs or you have already ensured that the ground and power wires are secure and correctly attached, then I next recommend making sure the lights themselves are good. Test them independently just to be certain that they are in good working order.

If you still are having trouble finding the problem please let me know and we can continue to troubleshoot.

expert reply by: Chris R