Troubleshooting Trailer Wiring Where Only Right Turn/Stop Signal isn't Working

Question:

Flatbed trailer w/ rear gate. Lights and all functions on the left side work perfectly. Right side running lights and brake lights work perfectly. Only thing that doesn’t work is the right turn directional. The bolts are the ground with these lights. So made sure clean bare metal was showing including filing down the inside of the holes for the bolts. Used contact cleaner and dialectic grease and cleaned bulb contact areas this way but no luck at all! Help!

asked by: Dave L

Expert Reply:

Sounds like an issue on the tow vehicle since the light activates like it should with the brake lights. That means the trailer wiring is correct but the signal is just not present on the tow vehicle like it needs to be. It almost has to be a fuse on the vehicle too since the corresponding brake light circuit is also activating like it should so that would be what I would check first.

I attached a help article with more troubleshooting info on trailer wiring for you to check out as well.

expert reply by: Jameson C