Seat Belt Tension Sensor
WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.
The seat belt tension sensor is a sensor mounted on the passenger seat belt retractor and provides an input to the passenger presence module. When an infant car seat is properly restrained on the front passenger seat, the seat belt is tightly secured through the car seat. The seat belt pulls on the tension sensor and changes the voltage signal to the passenger presence module. If the shoulder portion of a passenger belt is pulled out all the way, the child restraint locking feature may be engaged and may disable the passenger air bag.