WARNING: This page is about a different car, the 2011 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Power, Ground and Serial Data Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Monitored/Controlled References (1 of 3) Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 3: Monitored/Controlled References (2 of 3) Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 4: Monitored/Controlled References (3 of 3) Wiring Schematic