DTC B1000: Body Control Module Malfunction: Description
WARNING: This page is about a different car, the 2002 Pontiac Grand Am and 2002 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.
Body Control Module (BCM) performs a self-test when ignition switch is turned to RUN position. Only requirements are voltage and ground. Program runs even if voltage is out of valid operating range. If BCM detects an internal error, DTC B1000 sets, SERVICE VEHICLE SOON light illuminates and check gauges chime sounds.