GMC Sierra Classic 2007 Owner's Manual page 92

The frontal airbags (driver and right front
passenger) are not intended to inflate during
vehicle rollovers, rear impacts, or in many
side impacts.
In any particular crash, no one can say whether
an airbag should have inflated simply because
of the damage to a vehicle or because of what the
repair costs were. Inflation is determined by
what the vehicle hits, the angle of the impact, and
how quickly the vehicle slows down.
The airbag system is designed to work properly
under a wide range of conditions, including off-road
usage. Observe safe driving speeds, especially
on rough terrain. As always, wear your safety belt.
See Off-Road Driving on page 366 for more tips
on off-road driving.
92
Single Stage vs. Dual Stage Airbags
Depending on the weight of your vehicle, you will
have either "Single Stage Airbags" or "Dual
Stage Airbags." Vehicles that have a passenger
sensing system also have dual stage airbags.
If the rearview mirror in your vehicle has a
passenger airbag status indicator, your vehicle
has the passenger sensing system and therefore,
it has dual stage airbags. If the rearview mirror
in your vehicle does not have a passenger airbag
status indicator, then your vehicle does not
have the passenger sensing system and it has
single stage airbags. See Passenger Airbag Status
Indicator on page 248 or Passenger Sensing
System on page 99.