Troubleshooting Trailer Running Lights on Right Side Not Working

Question:

brand new trailer tailight I just bought it may be bad wire connection?

asked by: Bryan P

Expert Reply:

If the running lights on your right (or passenger) side are working, but they are working for the other side then this indicates that you either have a short, some damaged wiring, or your running light (or just the bulb) on the left side needs to be replaced.

Since trailer running lights on both sides use the same wiring you know that your trailer is getting the power because one side is lighting up. Start at your trailer plug and work your way back to your running light on the right side being sure to look for any places where the ground isn't securely connected to a clean bare-metal surface, or bent/damaged wiring and fix accordingly with 16 Gauge Wire # DW02359-1 and Heat Shrink Butt Connectors # DW05744-5.

If you don't see any damage or your lights still aren't working after fixing the bad wiring then you either need to replace the bulb or the entire assembly.

I have attached a helpful article on troubleshooting trailer wiring that you can check out.

expert reply by: Jon G

Bryan P.

12/6/2019

brand new trailer tailight I just bought it may be bad wire connection?

Jon G.

12/6/2019

If it's a brand new trailer tail light then I would hope that it is functioning properly which would mean that you need to perform the maintenance I mentioned for your wiring and any grounds. Again, if the wiring and grounds look good then you could have potentially received a bad tail light that needs to be exchanged, but you need to thoroughly check the rest of your trailer wiring before you jump to the conclusion that it's a bad tail light.