A Supplemental Restraint System - or SRS Airbag - is a safety measure that’s routinely found in modern vehicles. These devices are intended to provide protection, in addition to the seatbelt, in the event of an accident. They are made from stretchable fabrics and are tightly compressed into various locations around your vehicle: steering wheel, dashboard, side doors, etc.
The airbag system is one of the most important components in your vehicles safety system. When there is an accident, airbags fill up with air very quickly to provide a cushioning system for the people in the car. Proper airbag deployment is critical for survival and protection from injury during a crash. Airbags save lives. But how do they work?
If your vehicle is in an accident where it hits another vehicle or object or is hit, the airbag sensor (also known as the airbag ECU) will signal the airbag to open. Airbag sensors are small pieces of electronics are designed to tell when the vehicle has been damaged in an accident. These sensors respond to several different sets of stimuli, including sudden stopping, increased pressure as pieces of the car are moved due to the force of the collision, and more.
Impact sensors that measure the direction and intensity of an impact in the front, rear and sides of the vehicle. Seat sensors that determine if someone is sitting there as well as how much they weigh, to prevent an airbag from going off when no one is in a particular seat and or deploying with too much force for a smaller person. Sensors measuring wheel speed brake pressure and impact and other vehicle status indicators are monitored by the airbag control unit located in the front portion of the cabin.
The sensors relay signals to the airbag control unit, which analyzes the data and invokes safety features like seat belt lock, automatic door locks, as well as airbag deployment. When the control unit determines there is an accident, it sends a signal to the inflator system. The inflator sets off a chemical charge, producing an explosion of nitrogen gas, filling up the airbag. As the airbag fills up, it bursts through the panelling that contains it and enters into the space of the car in order to protect you.
This all happens in an instant, usually within 25 or 50 milliseconds. That translates to almost 200 miles per hour. The airbag then will deflate itself on its own once it deploys.
When you start your engine, you will briefly see the SRS dash light come on and then turn off. This is a system self-test. If the SRS light remains illuminated, that means the system has detected a problem that could affect the proper deployment of your airbags.