Chevrolet 2003 Silverado 1500 Pickup Owner's Manual page 73

Single Stage Air Bags
If your vehicle has frontal air bags with single stage
deployment and your vehicle goes straint into a wall that
doesn't move or deform, the threshold level is about
13 to 16 mph (20 to 25 km/h). The threshold level
can vary, however, with specific vehicle design, so that
it can be somewhat above or below this range.
If your vehicle strikes something that will move or
deform, such as a parked car, the threshold level will be
higher. The air bag is not designed to inflate in
rollovers, rear impacts, or in many side impacts because
inflation would not help the occupant.
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.
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.
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