I found this by pure happenstance. It contains all the electrical diagrams, chassis diagrams...etc...and all in nice, easy to search PDF files. You can find data all the way back to 1999.
Enjoy, it helped me immensely to wire my foglights and understand what GM did for my Suburban.
https://www.gmupfitter.com/pdflists/view/39
Enjoy, it helped me immensely to wire my foglights and understand what GM did for my Suburban.
https://www.gmupfitter.com/pdflists/view/39