Savana Special
WARNING: This page is about a different car, the 2003 GMC Savana Special, 2003 GMC Savana Camper Special, 2003 GMC Savana, and 2003 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
For G3500, see SYSTEM WIRING DIAGRAMS - G3500 in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.