Which Fuse In My 2005 GMC Sierra Powers The Trailer Running Light Circuit?

Published 10/08/2021

Question:

I was finally Hooking up a Trailer harness on my boat trailer ~Submersible, Under 80inch Trailer Light Kit with 25foot Wiring Harness purchased a while ago and had all lights working except front side lights. got the driver side hooked up and moved to the passenger side. That side did not work so I went to trouble shoot the light socket and Shorted out the truck by putting the probe in the light socket. Bad move as i found out but still couldnt find any blown fuses anywhere unless I missed it . but did pull alot of them and checked but none were blown, Still no power to the 7 Pin on back of Truck.

asked by: Stanley D

Expert Reply:

The fuse for the trailer running lights on your 2005 GMC Sierra 1500 is going to be located in the engine bay fuse box and will be labeled as the trailer parking lights.

If you just visually inspected the fuse it may have been missed because not all fuses are super visible when blown. You will want to use your circuit tester to test each contact on the top of the fuse and see if power is making its way through the fuse.

Once the fuse is replaced then you can check the wiring to the passenger side front clearance light. It should have a brown wire running to the brown wiring on your trailer connector, and it will either have a ground wire or will ground through the mounting hardware. Make sure the ground wire is connected to clean corrosion free metal, or if it grounds through the mounting hardware you will want to make sure the light is connected to metal with no plastic getting between the light and trailer frame.

I went ahead and included a link to a helpful article on troubleshooting trailer wiring for you to take a look at.

expert reply by: Samuel C