WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Valve Controls and Brake Switch Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Switch Inputs Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 3: Tow/Haul and PNP Switches Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 4: Vehicle Speed and 4WD Signal Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 5: Auxiliary Pump Controls Schematic - Hybrid Only