WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: 6-Way Power (-AN3) Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Module Power, Ground, Serial Data & Memory Switch (AN3) Schematic