WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Radio Power, Ground, DLC and Audio Communications Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Speakers +UX8 Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 3: Speakers +UY5 Schematic (1 of 3)
Courtesy of GENERAL MOTORS CORP.
Fig 4: Speakers +UY5 Schematic (2 of 3)
Courtesy of GENERAL MOTORS CORP.
Fig 5: Speakers +UY5 Schematic (3 of 3)
Courtesy of GENERAL MOTORS CORP.
Fig 6: Radio Antennas, Audio/Video Adapter Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 7: Digital Radio Receiver +U2K Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 8: Traffic Information Receiver Module (VICS) Schematic - Japan Only
Courtesy of GENERAL MOTORS CORP.
Fig 9: TV Tuner Assembly Schematic (North America)