GMC 2007 Acadia - Manual (Page 218)

If the airbag readiness light stays on after you
start the vehicle or comes on when you are driving,
your airbag system may not work properly.
Have your vehicle serviced right away.
{ CAUTION:
If the airbag readiness light stays on after
you start your vehicle, it means the airbag
system may not be working properly. The
airbags in your vehicle may not inflate in
a crash, or they could even inflate without
a crash. To help avoid injury to yourself
or others, have your vehicle serviced right
away if the airbag readiness light stays
on after you start your vehicle.
The airbag readiness light should flash for a
few seconds when you turn the ignition key to ON.
If the light does not come on then, have it fixed
so it will be ready to warn you if there is a problem.
Passenger Airbag Status Indicator
Your vehicle has the passenger sensing system.
Your instrument panel has a passenger airbag
status indicator.
When you start the vehicle, the passenger airbag
status indicator will light ON and OFF, or the
symbol for on and off, for several seconds as a
system check. If you use remote start to start your
vehicle from a distance, if your vehicle has this
feature, you may not see the 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 and seat-mounted
side impact airbags.
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