Circuit Description
WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) compares the restraints ID that is stored in the SDM to the restraints ID that is stored in the body control module (BCM). The restraints ID that is being compared contains the last four digits of the SDM part number. Also, the VIN that is stored in the SDM is compared to the VIN that is stored in the powertrain control module (PCM). For more detailed information concerning the Class 2 data lines, refer to Data Link Communications Description and Operation in Data Link Communications.