GMC Sierra Denali 2006 Owner's Manual page 146

If the word ON or the on symbol is lit on the passenger
airbag status indicator, it means that the right front
passenger's frontal airbag is enabled (may inflate).
CAUTION:
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If the on indicator comes on when you have a
rear-facing child restraint installed in the right
front passenger's seat, it means that the
passenger sensing system has not turned off
the passenger's frontal airbag. A child in a
rear-facing child restraint can be seriously
injured or killed if the right front passenger's
airbag inflates. This is because the back of the
rear-facing child restraint would be very close
to the inflating airbag. Do not use a rear-facing
child restraint in the right front passenger's
seat if the airbag is turned on.
If the word OFF or the off symbol is lit on the airbag
status indicator, it means that the passenger sensing
system has turned off the right front passenger's frontal
airbag. See Passenger Sensing System on page 1-56
for more on this, including important safety information.
3-32
If, after several seconds, all status indicator lights
remain on, or if there are no lights at all, there may
be a problem with the lights or the passenger sensing
system. See your dealer for service.
CAUTION:
{
If the off indicator and the airbag readiness
light ever come on together, it means that
something may be wrong with the airbag
system. If this ever happens, have the vehicle
serviced promptly, because an adult-size
person sitting in the right front passenger seat
may not have the protection of the frontal
airbag. See Airbag Readiness Light on
page 3-30.