WARNING: This page is about a different car, the 2007 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Dash Integration Module (DIM) Power, Ground, and Serial Data Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 2: Ignition Switch Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 3: DIM Inputs and Outputs Schematics - 1 of 3
Courtesy of GENERAL MOTORS CORP.
Fig 4: DIM Controlled/Monitored Subsystem References Schematics - 2 of 3
Courtesy of GENERAL MOTORS CORP.
Fig 5: DIM Inputs and Outputs Schematics - 3 of 3
Courtesy of GENERAL MOTORS CORP.
Fig 6: Rear Integration Module (RIM) Power, Ground, and Serial Data Schematics
Courtesy of GENERAL MOTORS CORP.
Fig 7: RIM Controlled/Monitored Subsystem References Schematics - 1 of 2
Courtesy of GENERAL MOTORS CORP.
Fig 8: RIM Controlled/Monitored Subsystem References Schematics - 2 of 2