WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Radio/Audio System Schematic (Power and Ground)
Courtesy of GENERAL MOTORS CORP.
Fig 2: Radio/Audio System Schematic (Speakers-UQ3)
Courtesy of GENERAL MOTORS CORP.
Fig 3: Radio/Audio System Schematic (Audio Amplifier)
Courtesy of GENERAL MOTORS CORP.
Fig 4: Radio/Audio System Schematic (Speakers-U85)