WARNING: This page is about a different car, the 2011 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Power, Ground, References and Antennas Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Amplifier Wiring Schematic - UQA
Courtesy of GENERAL MOTORS CORP.
Fig 3: Speakers Wiring Schematic - UQA
Courtesy of GENERAL MOTORS CORP.
Fig 4: Speakers Wiring Schematic - UQ3
Courtesy of GENERAL MOTORS CORP.
Fig 5: Radio/HVAC Controls Wiring Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 6: Auxiliary Audio Input Wiring Schematic without USR
Courtesy of GENERAL MOTORS CORP.
Fig 7: Auxiliary Audio Input Wiring Schematic with USR