Circuit Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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 stored in the SDM to the restraints ID stored in the body control module (BCM). The restraints ID being compared contains the last four digits of the SDM part number. For more detailed information concerning Class 2 serial data lines, refer to Data Link Communications Description and Operation in Data Link Communications.