WARNING: This page is about a different car, the 2005 GMC Sierra and 2005 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Driver Door Module (DDM) Power, Ground, Serial Data and References Schematic - 1 of 2
Courtesy of GENERAL MOTORS CORP.
Fig 2: Driver Door Module (DDM) References Schematic - 2 of 2
Courtesy of GENERAL MOTORS CORP.
Fig 3: Passenger Door Module (PDM) Power, Ground, Serial Data and References Schematic - 1 of 2
Courtesy of GENERAL MOTORS CORP.
Fig 4: Passenger Door Module (PDM) References Schematic - 2 of 2