Chevrolet 2003 Silverado 1500 Pickup Owner's Manual page 83

If this happens and the switch is in the proper position,
turn the vehicle off and ask the person to place the
seatback in the full 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 air bag.
If the air bag readiness light in the instrument
panel cluster ever comes on and stays on, it
means that something may be wrong with the
air bag 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 air bag. See "Air Bag Readiness
Light" in the Index 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.
1-76