WARNING: This page is about a different car, the 2003 Saturn LW300, 2003 Saturn LW200, 2003 Saturn L300, and 2003 Saturn L200. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: BCM Power, Ground, and Serial Data Schematic
Courtesy of GENERAL MOTORS CORP.
Fig 2: Lighting, Defogger, and Wipers References Schematic