Troubleshooting Trailer Running Lights Not Working

Question:

Trailer lights My running lights don’t work but everything else works

asked by: Scott S

Expert Reply:

The running lights are on a different pin than every other wire on your trailer. It is very likely that you have some corrosion on the running light pin at your trailer connection. Use a little sandpaper or steel wool to clean the pins and then use a little dielectric grease like # 11755 to keep the pins from corrosion. Also check your ground wire on your trailer to make sure it is a bare metal to metal connection free of corrosion, rust, and debris.

You can test your wiring harness using a circuit tester like # PTW2993 to ensure each pin on your vehicle is working correctly. This will also allow you to probe the running light wire on your trailer to help you find a short if the trailer connector isn't the issue. Replace with # 16-1-1 as needed. I've attached a wiring article that includes diagrams to assist.

Some vehicles also have a separate fuse for trailer running/parking lights so you will want to check your owner's manual.

expert reply by: Jason S