Seat Belt Systems: Description and Operation

The SRS is a safety device which, when used in conjunction with the seat belt, is designed to help protect the driver and front passenger in a frontal impact exceeding a certain set limit. The system consists of the SRS unit (including safing sensor and impact sensor), the cable reel, the driver's airbag, and front passenger's airbag.

The seat belt tensioner is linked with the SRS airbags to further increase the effectiveness of the seat belt. In a front-end collision, the tensioner instantly retracts the belt firmly to secure the occupants in their seats.

Operation
The main circuit in the SRS unit senses and judges the force of impact and, if necessary, ignites the inflator charges. It battery voltage is too low or power is disconnected due to the impact, the back-up power circuit will keep voltage at a constant level.