Chevrolet 2006 TrailBlazer EXT Owner's Manual page 73

If a person of adult-size is sitting in the right front
passenger's seat, but the off indicator is lit, it could be
because that person is not sitting properly in the seat. If
this happens, turn the vehicle off and ask the person to
place the seatback in the fully upright position, then sit
upright in the seat, centered on the seat cushion, with the
person's legs comfortably extended. Restart the vehicle
and have the person remain in this position for about
two minutes. This will allow the system to detect that
person and then enable the passenger's airbag.
CAUTION:
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If the airbag readiness light in the instrument
panel cluster ever comes on and stays on,
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's seat may not have the protection
of the frontal airbag. See Airbag Readiness
Light on page 3-34 for more on this, including
important safety information.
Aftermarket equipment, such as seat covers, can affect
how well the passenger sensing system operates.
You may want to consider not using seat covers or other
aftermarket equipment if your vehicle has the passenger
sensing system. See Adding Equipment to Your
Airbag-Equipped Vehicle on page 1-69 for more
information about modifications that can affect how the
system operates.
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