GM Service Manual Online
For 1990-2009 cars only
Driver Seat Belt Switch: The scan tool displays the current status of the driver seat belt switch. The scan tool will display Buckled when the driver seat belt is buckled and Unbuckled when the belt is unbuckled.

Passenger Seat Belt Switch: The scan tool displays the current status of the passenger seat belt switch. The scan tool will display Buckled when the passenger seat belt is buckled and Unbuckled when the belt is unbuckled.