July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!
Navigation System Schematics
WARNING: This page is about a different car, the 2004 Cadillac Seville. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Power, Ground, Components, and GPS Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Auxiliary RCA Video Jacks and Export Microphone Schematic