WARNING: This page is about a different car, the 2011 Chevrolet Volt. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: High Speed GMLAN Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: High Voltage Management And Powertrain Expansion Busses Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 3: Chassis Expansion Bus Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 4: Low Speed CAN Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 5: Communications Enable Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 6: Serial Data Wake-Up
Courtesy of GENERAL MOTORS CORP.
Fig 7: Linear Interconnect Network (LIN) Wiring Schematic