Troubleshooting Why Only One Trailer Taillight Works at a Time

Updated 08/23/2021 | Published 08/22/2021

Question:

The right light on my trailer was not working so I replaced it. cut the wires and connected all matching colors back together. The right side worked great, but for some reason the left side stopped working. I went and bought a new light even though the other left light was just working prior to me fixing the right light. Put in the new left light, now the left side works and the right side doesnt. Im so confused as to how the could be happening. any help would be appreciated.

asked by: Kristin

Expert Reply:

Sounds like your trailer doesn't have enough of a ground circuit to power both of your trailer taillights at the same time which is why only one of them is working at a time. So what you can do is improve the grounds of the lights and you should see the lights work again. You can do this by running a jumper wire from the light assemblies up to the main ground of the trailer and also verify that the grounds of each light is connected properly to a clean ground circuit.

expert reply by: Jameson C