Troubleshooting Trailer's Right Turn Signal that is No Longer Working

Question:

Hello, I have a 2007 F-150 Supercrew Cab. I was towing a 24foot Enclosed Trailer and my right turning signal is no longer working on the towing harness. It still works fine on my truck, once I tried hooking any type of trailer to it. The right side still doesnt work. I had got a light tester and moved some wires around, but no results were made. The left signal works just fine with and without a trailer. Does anyone know what can cause this to happened? What can I do to fix this?

asked by: Carlos

Expert Reply:

It sounds like you have a short on the right turn/brake light circuit. This is the pin in the 3 O'clock position on the 7-way at the back of your truck, and the 9 O'clock position on the trailer. The first thing to do is to make sure these are clean of debirs and corrosion.

Next check the fuse. According to an online owner's manual, your truck's "Trailer tow right turn/stop lamps" fuse is in location 36. You might check your owner's manual first just to be sure.

If it's not that simple use your tester on the same pin of the truck's connetor with the right turn signal engaged. If you aren't showing power here then there is a problem with the trailer wiring harness or somewhere else in your truck.

If you do have power at the truck's 7-way the problem is with the trailer's wiring. You'll need to inspect the wires running from the back of the trailer's 7-way connector to the light. You're looking for any pinches, damage, or any places where the bare wire is exposed.

If you've verified all of this is in working order, let me know and we'll continue troubleshooting.

expert reply by: Charles S