WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 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 Schematic - L26
Courtesy of GENERAL MOTORS CORP.
Fig 2: Power, Ground, Serial Data, and Gages Schematic - LY7
Courtesy of GENERAL MOTORS CORP.
Fig 3: Ambient Air Temperature Sensor, Electronic Compass Module & Oil Level Switch Schematic