WARNING: This page is about a different car, the 2005 GMC Savana and 2005 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Module Power, Ground, Serial Data and MIL Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 2: Engine Data Sensors - 5-Volt and Low Reference Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 3: Engine Data Sensors - Pressure, Temperature and Position Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 4: Engine Data Sensors - Oxygen Sensors Schematics