I have a 2007 Yukon XL and was having a similar issue with the trailer lights when I came across this post. I looked under the hood in the main fuse box and sure enough it was a blown fuse. It was the trailer stop rt fuse.
A forum community dedicated to all General Motors truck owners and enthusiasts. Come join the discussion about performance, lift kits, wheels, tires, modifications, troubleshooting, maintenance, and more!