Where does this ground wire go to?

[Tonyrodz]

I'm STILL clueless about a few of the smaller changes that GM did in 03. LOL
Like I just recently realized that the map lights in the overhead console also turned on with the dome light in 03+ trucks. I had to rewire mine and add a relay and two diodes in order to get them to turn on with the door switches AND still function as normal button operated map lights when the doors are closed.

It's an ongoing learning process. GM has no rhyme or reason in the things they do. Back in the day you could get cars with power locks and manual windows. Go figure.