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Home >> Volvo >> 2007 >> S40 Base, 2.4 38, Automatic >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Miscellaneous Components - Design And Function (544 Body) >> Supplemental Restraint System Control Module (SRS) (2004-2007) >> Design >> Front Airbags
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Front Airbags

Fig 1: Identifying Front Airbags
GLL117746Courtesy of VOLVO CARS OF NORTH AMERICA.
WARNING:

Never use an ohmmeter or similar tool to test airbags, inflatable curtains, adaptive seatbelt limiters, adaptive steering column or seat belt tensioners. Disconnect airbags, inflatable curtains adaptive seatbelt limiters, adaptive steering column or seat belt tensioners before testing them. Failure to do so may result in accidental deployment. This could result in serious injury or death.

The airbags at the front of the vehicle are:

The driver's airbag is located in the steering wheel. The passenger airbag is located above the glove compartment in the dashboard.

The front airbags have two ignition components each. These are electrically separated from each other. This means that the different ignition components have their own separate power supply and grounding points from the control module. Two power supply outputs are required from the control module for each airbag, one for each ignition component. This means that in total four pins on the control module, two power supply pins and two ground pins, are used for each airbag.

When activating the airbags, electrical signals are transmitted from the supplemental restraint system module (SRS) to the relevant airbag stage.

Stage 1 

Stage 1 of the driver's airbag is pyrotechnic. In the event of deployment, the charge combusts and the gas which develops is blown into the airbag.

Stage 1 on the passenger airbag consists of a pyrotechnic component in combination with a reservoir which stores a gas. On activation the pyrotechnic charge and mixes with the stored gas. The gas mixture is blown into the airbag.

Stage 2 

Stage 2 of the driver's and passenger airbags is pyrotechnical. In the event of deployment, the charge combusts and the gas which develops is blown into the airbag.

The pace of the airbag 2 stage activation is dependent on collision type and seat belt use. Both stages activate but in the event of a lesser impact, there is a greater time delay between stage 1 and stage 2. For more serious impacts the time delay is shorter between stages 1 and 2.

WARNING:

Never use an ohmmeter or similar tool to test airbags, inflatable curtains, adaptive seatbelt limiters, adaptive steering column or seat belt tensioners. Disconnect airbags, inflatable curtains adaptive seatbelt limiters, adaptive steering column or seat belt tensioners before testing them. Failure to do so may result in accidental deployment. This could result in serious injury or death.