1. Inspect the belts, buckles, and belt attachments to the body for visible damage or wear.
2. Check if the reminder signal on the dashboard lights up when the ignition is turned on. In this case, the sound signal should also work. If the car is equipped with belts with inertia drums, check if the shoulder belt retracts into the center pillar.
3. The seat belt should prevent the movement of the torso during sudden braking or collision, but during normal movement it should give a certain freedom of movement. Make sure the drums pull the belt across your chest when the vehicle is moving, and fully retract the belt into the upright when the buckle is released.
4. If at least one of the indicated checks gave a negative result, replace the corresponding parts or assembly.