2004 GMC Savana Van Owner's Manual - Page 79

Seat Position Sensors Vehicles with dual stage air bags are also equipped with special sensors which enable the sensing system to monitor the position of both the driver and passenger front seats. The seat position sensors provide information which is used to determine if the air bags should deploy at a reduced level or at full depoyment. What Makes an Air Bag Inflate? In an impact of sufficient severity, the air bag sensing system detects that the vehicle is in a crash. The sensing system triggers a release of gas from the inflator, which inflates the air bag. The inflator, air bag, and related hardware are all part of the air bag modules inside the steering wheel and in the instrument panel in front of the right front passenger. Air Bag Systems In any particular crash, no one can say whether an air bag should have inflated simply because of the damage to a vehicle or because of what the repair costs were. Inflation is determined by the angle of the impact and how quickly the vehicle slows down in front or near-frontal impacts. How Does an Air Bag Restrain? In moderate to severe frontal or near-frontal collisions, even belted occupants can contact the steering wheel or the instrument panel. Air bags supplement the protection provided by safety belts. Air bags distribute the force of the impact more evenly over the occupant's upper body, stopping the occupant more gradually. But air bags would not help you in many types of collisions, including rollovers, rear impacts and many side impacts, primarily because an occupant's motion is not toward those air bags. Air bags should never be regarded as anything more than a supplement to safety belts, and then only in moderate to severe frontal or near-frontal collisions. 1-73