Air Bag Systems: Description and Operation

System is activated by sensors, whereby there must be a vehicle deceleration equal to a direct head-on collision of at least 18 km/h against a solid (non-resilient) obstacle.

Electric circuit is made and gas generators ignited. In the process, flash combustion of solid-propellant mixture causes non-toxic gases to be released, which fully inflate folded airbag in steering wheel and in instrument panel within approx. 30 ms.

Crash-inflated airbag reduces severity of injury to head and upper part of body in head-on collisions. Airbag deflates through two holes at side of bag, which point away from driver/passenger.

Monitoring

Airbag I system is monitored continuously by a diagnosing unit from ignition lock position "1". Indicator light illuminates and goes back out after about 6 seconds - Airbag II approx. 4 seconds signalling that system is ready to operate.

If this indicator light comes on again, a fault has been detected in the system. Self-diagnosis - fault memory inquiry with BMW DIAGNOSIS SYSTEM. Airbag II troubleshooting refer to