Sensing & Diagnostic Module (SDM)
WARNING: This page is about a different car, the 2000 Buick Park Avenue. However, it is still accessible from the selected car via links, so may be relevant.
SDM monitors vehicle velocity changes to detect frontal crashes which are severe enough to warrant air bag module deployment. When a frontal crash of sufficient force is detected, SDM causes enough current flow through air bag modules to deploy air bags. SDM also maintains a 23 Volt Loop Reserve (23 VLR) energy supply to provide deployment energy for up to 10 minutes after loss of voltage.
Additionally, SDM provides diagnostic monitoring of SIR system electrical components. When a malfunction is detected, SDM sets a Diagnostic Trouble Code (DTC) which can be retrieved using a scan tool. SDM warns driver of system malfunctions by controlling AIR BAG warning light.