Air Bag Systems: Description and Operation

Air Bag Supplemental Restraint System (SRS)

Principle of operation
The SRS is an intelligent system, in that it deploys the appropriate airbag module for any impact event, based on information provided by the sensors around the vehicle.

Working in conjunction with the safety belt system, the SRS will provide the maximum protection for the vehicle occupants wherever the impact occurs.

In the event of a severe frontal impact, the restraints control module (RCM) will deploy the safety belt pretensioners and/or the front airbags as necessary, by measuring the impact via the crash sensor and comparing the measurement against data stored in it's memory.

In the event of a side impact, the RCM uses information from the side impact sensors to determine if the thoracic and/or curtain airbags should be deployed.

Occupancy classification sensor
In addition to determining the best deployment of the airbags from impact data, the system uses information from the occupancy classification sensor to control the two-stage airbag used in the passenger airbag module, and relays this information to the occupants via the passenger airbag deactivation (PAD) lamp.







Seat track position sensor
To determine the level of deployment of the front airbag modules, the system also uses inputs from the seat track position sensor.

The system will not deploy the second stage of the airbag if the front occupants are too close to the front airbag modules.

Warning tones
In the event of a second fault occurring whilst there is a warning light fault, there will be an audible warning, initiated by the instrument cluster.

This secondary warning will be activated when the SRS system detects any additional fault, other than a warning light fault.

The secondary warning will consist of five sets of five tone bursts, each set of five tones being separated by a five second silence.

This sequence will be repeated approximately every 30 minutes.