1996 GMC Jimmy Owner's Manual - Page 32

When should an air bag inflate? The air bag is designed to inflate in moderate to severe frontal or near-frontal crashes. The airbag will inflate only if the impact speed is above the system's designed "threshold level." If your vehicle goes straight into a wall that doesn't move or deform, the threshold level is about 14 to I8 mph (23 to 29 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, side impacts or rear impacts, because inflation would not help the occupant. What makes an air bag inflate? In a frontal or near-frontal impact of sufficient severity, the air bag sensing system detects thatthe vehicle is suddenly stopping as a result of a crash. The sensing system triggers a chemical reaction of the sodium azide sealed in the inflator. The reaction produces nitrogen gas, which inflates the air bag. The inflator?air bag and related hardware are allpart of the air bag module packed inside the steering wheel. How does an air bag restrain? In moderate to severe frontal or near-frontal collisions, even belted occupants can contact the steering wheel. The air bag supplements 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 side impacts, primarily because an occupant's motion is not toward the air bag. 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. 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 the vehicle's deceleration. Vehicle damage is only one indication of this. The air bag system is designed to work properly under a wide range of conditions, includingoff-road usage. Observe safe driving speeds, especially rough terrain. on As always, wear your safety belt. See "Off-Road Driving" in the Index for more tips on off-road driving. 1-21