2008 GMC Envoy Owner's Manual - Page 62

When Should an Airbag Inflate? Frontal airbags are designed to inflate in moderate to severe frontal or near-frontal crashes to help reduce the potential for severe injuries mainly to the driver's or right front passenger's head and chest. However, they are only designed to inflate if the impact exceeds a predetermined deployment threshold. Deployment thresholds are used to predict how severe a crash is likely to be in time for the airbags to inflate and help restrain the occupants. Whether your frontal airbags will or should deploy is not based on how fast your vehicle is traveling. It depends largely on what you hit, the direction of the impact, and how quickly your vehicle slows down. Frontal airbags may inflate at different crash speeds. For example: • If the vehicle hits a stationary object, the airbags could inflate at a different crash speed than if the vehicle hits a moving object. • If the vehicle hits an object that deforms, the airbags could inflate at a different crash speed than if the vehicle hits an object that does not deform. • If the vehicle hits a narrow object (like a pole), the airbags could inflate at a different crash speed than if the vehicle hits a wide object (like a wall). • If the vehicle goes into an object at an angle, the airbags could inflate at a different crash speed than if the vehicle goes straight into the object. 1-58 Thresholds can also vary with specific vehicle design. Frontal airbags are not intended to inflate during vehicle rollovers, rear impacts, or in many side impacts. In addition, your vehicle has dual-stage frontal airbags. Dual-stage airbags adjust the restraint according to crash severity. Your vehicle has electronic frontal sensors, which help the sensing system distinguish between a moderate frontal impact and a more severe frontal impact. For moderate frontal impacts, dual-stage airbags inflate at a level less than full deployment. For more severe frontal impacts, full deployment occurs. Your vehicle has seat position sensors which enables the sensing system to monitor the position of the driver's and right front passenger's seat. The sensors provide information that is used to determine if the airbags should deploy at a reduced level or at full deployment. Your vehicle has roof-rail airbags. See Airbag System on page 1-53. Roof-rail airbags are intended to inflate in moderate to severe side crashes. In addition, these roof-rail airbags are intended to inflate during a rollover. Roof-rail airbags will inflate if the crash severity is above the system's designed threshold level. The threshold level can vary with specific vehicle design. Roof-rail airbags are not intended to inflate in frontal impacts, near-frontal impacts, or rear impacts. Both roof-rail airbags will deploy when either side of the vehicle is struck or if the sensing system predicts that the vehicle is about to roll over.