WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Power, Ground, Serial Data & Gages (L26) Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Power, Ground, Serial Data & Gages (LY7) Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 3: Indicators (U2E) Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 4: Indicators (UH8) Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 5: Ambient Air Temperature Sensor, Electronic Compass Module & Oil Level Switch Schematic