There is a driver seat belt reminder light on the instrument cluster.

When the vehicle is started, this light flashes and a chime may come on to remind the driver to fasten their seat belt. Then the light stays on solid until the belt is buckled.
This cycle may continue several times if the driver remains or becomes unbuckled while the vehicle is moving.
If the driver seat belt is buckled, neither the light nor the chime comes on.
Passenger Seat Belt Reminder Light#03-00-89-006J: New Vehicle Pre-Delivery Inspection (PDI) - Delivering Quality Vehicles and Generating Higher CSi Scores - (Jun 19, 2013)
Subject:New Vehicle Pre-Delivery Inspection (PDI) – Delivering Quality Vehicles and GeneratingHigher CSi ScoresModels: 2014 and Prior GM Passenger Cars and Light Duty TrucksAttention: It is recommended that this bulletin be reviewed by the Vehicle Prep Department, ServiceManager and Sales Manage ...