GMC 2007 Sierra - Manual (Page 250)

Passenger Airbag Status Indicator
If your vehicle has the passenger sensing system,
your rearview mirror will have a passenger
airbag status indicator.
When the ignition key is turned to RUN or START,
the passenger airbag status indicator will light
ON and OFF, or the symbol for on and off,
for several seconds as a system check. Then,
after several more seconds, the status indicator
will light either ON or OFF, or either the on or off
symbol to let you know the status of the right
front passenger’s frontal airbag.
Your vehicle may have a label on your sun visor
that says, “Never put a rear-facing child seat in the
front.” This is because the risk to the rear-facing
child is so great, if the airbag deploys.
{ CAUTION:
Even though the passenger sensing
system is designed to turn off the
passenger’s frontal airbag if the system
detects a rear-facing child restraint, no
system is failsafe, and no one can
guarantee that an airbag will not deploy
under some unusual circumstance, even
though it is turned off. We recommend
that rear-facing child restraints be secured
in the rear seat, even if the airbag is off.
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