Fasten Safety Belt Warning

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.

The inflatable restraint sensing and diagnostic module (SDM) senses that the drivers seat belt is not buckled and the signal is low. The SDM sends a class 2 message to the instrument panel cluster (IPC) requesting illumination of the seat belt indicator. The SDM sends a class 2 message to the chime producer indicating a chime at the rate of 50 pulses per minute, slow rate chime, for a duration of approximately 6 seconds. The fasten safety belt warning sounds and the seat belt indicator illuminates when the following occurs:

Ignition switch transitions to ON.
The seat belt switch signal to the SDM is low.

If the seat belt is buckled when the ignition is turned ON, the chime will not sound. If the seat belt is buckled while the chime is sounding, the chime stops.