1.  The gas generator emits a spark when a signal is received from the SAS control module, causing gas to form.

2.  The gas pressure pushes the piston inside the tube, pulling the lead wire.

3.  As the lead wire is pulled, the part of the front seat belt (driver side) attached to the wire is also pulled.

4.  The slack in the belt is tightened due to the buckle being pulled and the seat belt ELR mechanism, safely restraining the driver.

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1.  After the pre-tensioners operate (deploy), the lead wire is pulled back. However the front seat belts are locked by activation of the stopper function so that the belt webbing is not released.

2.  The restraint force of the seat belt is adjusted by the return of the buckle together with the front seat belt load limiter mechanism, preventing injury to the driver and passenger due to seat belt pressure

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