WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Power, Ground, Serial Data, and Gages (L26) Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Power, Ground, Serial Data, and Gages (LY7) Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 3: Ambient Air Temperature Sensor, Electronic Compass Module, and Oil Level Switch Schematic