WARNING: This page is about a different car, the 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Power, Ground, Serial Data, MIL and Indicators Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 2: Underhood Fuse Block Main Relay Schematics (1 Of 2)
Courtesy of GENERAL MOTORS CORP.
Fig 3: Underhood Fuse Block Main Relay Schematics (2 Of 2)
Courtesy of GENERAL MOTORS CORP.
Fig 4: Engine Data Sensors - 5-Volt Reference Bus Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 5: Engine Data Sensors - Low Reference Bus Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 6: Engine Data Sensors - BARO, ECT and MAF/IAT Sensors Schematics