Circuit/System Description
WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
The inflatable restraint sensing and diagnostic module (SDM) sends the status of the driver seat belt switch to the instrument panel cluster (IPC) via a GMLAN serial data message. If the seat belt is unfastened, the SDM will send a message to the IPC to illuminate the fasten safety belt indicator for 72 seconds or until the seat belt is fastened.