WARNING: This page is about a different car, the 2006 Chevrolet Monte Carlo and 2006 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Power, Ground, and References - Wiring Diagram
Courtesy of GENERAL MOTORS CORP.
Fig 2: Radio to Speakers - UW6 - Wiring Diagram
Courtesy of GENERAL MOTORS CORP.
Fig 3: Audio Signal Communication - UQ3 - Wiring Diagram
Courtesy of GENERAL MOTORS CORP.
Fig 4: Audio Amplifier to Speakers - UQ3, Sedan - Wiring Diagram
Courtesy of GENERAL MOTORS CORP.
Fig 5: Amplifier to Speakers - UQ3, Coupe - Wiring Diagram
Courtesy of GENERAL MOTORS CORP.
Fig 6: Radio to Speakers - 9C1, 9C3, w/o WX7 - Wiring Diagram
Courtesy of GENERAL MOTORS CORP.
Fig 7: Radio to Speakers - 9C1, 9C3, and WX7 - Wiring Diagram