GMC SIERRA 1999 Owner's Guide

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CAUTION:
Children who are up against, or very close to, any
air bag when it inflates can be seriously injured or
killed. This is true even though your vehicle has
Next Generation frontal air bags. Air bags plus
lap
-shoulder belts offer the best protection for
adults, but not for young children and infants.
Neither the vehicle's safety belt system nor its air
bag system is designed for them. Young children
and infants need the protection that a child
restraint system can provide. Always secure
children properly in your vehicle. To read how, see
the part of this manual called ªChildrenº and see
the caution labels on the sunvisors and the right
front passenger's safety belt.
There is an air bag
readiness light on the
instrument panel, which
shows AIR BAG.
The system checks the air bag electrical system for
malfunctions. The light tells you if there is an electrical
problem. See ªAir Bag Readiness Lightº in the Index
for more information.

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1-26 How the Air Bag System Works
Where are the air bags?
The driver's air bag is in the middle of the
steering wheel.
The right front passenger's air bag is in the instrument
panel on the passenger's side.

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CAUTION:
If something is between an occupant and an air
bag, the bag might not inflate properly or it
might force the object into that person. The path
of an inflating air bag must be kept clear. Don't
put anything between an occupant and an air
bag, and don't attach or put anything on the
steering wheel hub or on or near any other air
bag covering.
When should an air bag inflate?
An air bag is designed to inflate in a moderate to severe
frontal or near
-frontal crash. The air bag will inflate
only if the impact speed is above the system's designed
ªthreshold level.º If your vehicle goes straight into a
wall that doesn't move or deform, the threshold level is
about 9 to 16 mph (14 to 26 km/h). The threshold level
can vary, however, with specific vehicle design, so that
it can be somewhat above or below this range. If your vehicle strikes something that will move or
deform, such as a parked car, the threshold level will be
higher. The air bag is not designed to inflate in rollovers,
side impacts or rear impacts, because inflation would
not help the occupant.
In any particular crash, no one can say whether an air
bag should have inflated simply because of the damage
to a vehicle or because of what the repair costs were.
Inflation is determined by the angle of the impact and
how quickly the vehicle slows down in frontal or
near
-frontal impacts.
The air bag system is designed to work properly under a
wide range of conditions, including off
-road usage.
Observe safe driving speeds, especially on rough terrain.
As always, wear your safety belt. See ªOff
-Road
Drivingº in the Index for more tips on off
-road driving.
What makes an air bag inflate?
In an impact of sufficient severity, the air bag sensing
system detects that the vehicle is in a crash. The sensing
system triggers a release of gas from the inflator, which
inflates the air bag. The inflator, air bag and related
hardware are all part of the air bag modules inside the
steering wheel and in the instrument panel in front of the
right front passenger.

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How does an air bag restrain?
In moderate to severe frontal or near
-frontal collisions,
even belted occupants can contact the steering wheel or
the instrument panel. Air bags supplement the protection
provided by safety belts. Air bags distribute the force of
the impact more evenly over the occupant's upper body,
stopping the occupant more gradually. But air bags would
not help you in many types of collisions, including
rollovers, rear impacts and side impacts, primarily
because an occupant's motion is not toward those air
bags. Air bags should never be regarded as anything
more than a supplement to safety belts, and then only in
moderate to severe frontal or near
-frontal collisions.
What will you see after an air bag inflates?
After an air bag inflates, it quickly deflates, so quickly that
some people may not even realize the air bag inflated.
Some components of the air bag module
-- the steering
wheel hub for the driver's air bag, or the instrument panel
for the right front passenger's bag
-- will be hot for a short
time. The parts of the bag that come into contact with you
may be warm, but not too hot to touch. There will be some smoke and dust coming from vents in
the deflated air bags. Air bag inflation doesn't prevent the
driver from seeing or from being able to steer the vehicle,
nor does it stop people from leaving the vehicle.
CAUTION:
When an air bag inflates, there is dust in the air.
This dust could cause breathing problems for
people with a history of asthma or other
breathing trouble. To avoid this, everyone in the
vehicle should get out as soon as it is safe to do so.
If you have breathing problems but can't get out
of the vehicle after an air bag inflates, then get
fresh air by opening a window or door.

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In many crashes severe enough to inflate an air bag,
windshields are broken by vehicle deformation.
Additional windshield breakage may also occur from the
right front passenger air bag.

Air bags are designed to inflate only once. After they
inflate, you'll need some new parts for your air bag
system. If you don't get them, the air bag system
won't be there to help protect you in another crash.
A new system will include air bag modules and
possibly other parts. The service manual for your
vehicle covers the need to replace other parts.

Your vehicle is equipped with a crash sensing and
diagnostic module, which records information about
the air bag system. The module records information
about the readiness of the system, when the
sensors are activated and driver's safety belt usage
at deployment.

Let only qualified technicians work on your
air bag system. Improper service can mean that
your air bag system won't work properly. See your
dealer for service.
NOTICE:
If you damage the covering for the driver's or the
right front passenger's air bag, the bag may not
work properly. You may have to replace the air
bag module in the steering wheel or both the air
bag module and the instrument panel for the
right front passenger's air bag. Do not open or
break the air bag coverings.
If your vehicle ever gets into a lot of water -- such as
water up to the carpeting or higher
-- or if water enters
your vehicle and soaks the carpet, the air bag controller
can be soaked and ruined. If this ever happens, and then
you start your vehicle, the damage could make the air
bags inflate, even if there's no crash. You would have to
replace the air bags as well as the sensors and related
parts. If your vehicle is ever in a flood, or if it's exposed
to water that soaks the carpet, you can avoid needless
repair costs by turning off the vehicle immediately and
disconnecting the battery cables. Don't let anyone start
the vehicle under any circumstances. See your dealer
for service.

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1-30 AIR BAG OFF Switch
If your vehicle has air bags, it also has a switch on the
instrument panel that you can use to turn off the right
front passenger's air bag.
This switch should only be turned to AIR BAG OFF if
the person in the right front passenger's position is a
member of a passenger risk group identified by the
national government as follows:Infant. An infant (less than 1 year old) must ride in the
front seat because:

my vehicle has no rear seat;

my vehicle has a rear seat too small to accommodate
a rear
-facing infant seat; or

the infant has a medical condition which, according
to the infant's physician, makes it necessary for the
infant to ride in the front seat so that the driver can
constantly monitor the child's condition.
Child age 1 to 12. A child age 1 to 12 must ride in the
front seat because:

my vehicle has no rear seat;

although children ages 1 to 12 ride in the rear
seat(s) whenever possible, children ages 1 to 12
sometimes must ride in the front because no space is
available in the rear seat(s) of my vehicle; or

the child has a medical condition which, according
to the child's physician, makes it necessary for the
child to ride in the front seat so that the driver can
constantly monitor the child's condition.

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Medical Condition. A passenger has a medical
condition which, according to his or her physician:

causes the passenger air bag to pose a special risk
for the passenger; and

makes the potential harm from the passenger air bag
in a crash greater than the potential harm from
turning off the air bag and allowing the passenger,
even if belted, to hit the dashboard or windshield
in a crash.
CAUTION:
If the right front passenger's air bag is turned off
for a person who isn't in a risk group identified
by the national government, that person won't
have the extra protection of an air bag. In a
crash, the air bag wouldn't be able to inflate and
help protect the person sitting there. Don't turn
off the passenger's air bag unless the person
sitting there is in a risk group.
To turn off the right front passenger's air bag, insert
your ignition key into the switch, push in, and move the
switch to AIR BAG OFF.
The AIR BAG OFF light will come on to let you know
that the right front passenger's air bag is off. The right
front passenger's air bag will remain off until you turn it
back on again, and the AIR BAG OFF light will stay on
to remind you that the air bag is off.

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CAUTION:
If the air bag readiness light ever comes on when
you have turned off the air bag, it means that
something may be wrong with the air bag system.
The right front passenger's air bag could inflate
even though the switch is off.
If this ever happens, don't let anyone whom the
national government has identified as a member
of a passenger air bag risk group sit in the right
front passenger's position (for example, don't
secure a rear
-facing child restraint in the right
front passenger's seat) until you have your
vehicle serviced.
To turn the right front passenger's air bag on again,
insert your ignition key into the switch, push in, and
move the switch to the ON position.

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1-33 Servicing Your Air Bag-Equipped Vehicle
Air bags affect how your vehicle should be serviced.
There are parts of the air bag system in several places
around your vehicle. You don't want the system to
inflate while someone is working on your vehicle.
Your dealer and the service manual have information
about servicing your vehicle and the air bag system.
To purchase a service manual, see ªService and Owner
Publicationsº in the Index.CAUTION:
For up to 10 minutes after the ignition key is
turned off and the battery is disconnected, an air
bag can still inflate during improper service. You
can be injured if you are close to an air bag when
it inflates. Avoid wires wrapped with yellow tape
or yellow connectors. They are probably part of
the air bag system. Be sure to follow proper
service procedures, and make sure the person
performing work for you is qualified to do so.
The air bag system does not need regular maintenance.

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1-34 Adding Equipment to Your Air
Bag-Equipped Vehicle
Q:If I add a push bumper or a bicycle rack to the
front of my vehicle, will it keep the air bags
from working properly?
A:As long as the push bumper or bicycle rack is
attached to your vehicle so that the vehicle's basic
structure isn't changed, it's not likely to keep the
air bags from working properly in a crash.
Q:Is there anything I might add to the front of the
vehicle that could keep the air bags from
working properly?
A:Yes. If you add things that change your vehicle's
frame, bumper system, front end sheet metal or
height, they may keep the air bag system from
working properly. Also, the air bag system may not
work properly if you relocate any of the air bag
sensors. If you have any questions about this, you
should contact Customer Assistance before you
modify your vehicle. (The phone numbers and
addresses for Customer Assistance are in Step Two
of the Customer Satisfaction Procedure in this
manual. See ªCustomer Satisfaction Procedureº
in the Index.)
Q:What if I add a snow plow? Will it keep the air
bags from working properly?
A:We've designed our air bag systems to work
properly under a wide range of conditions,
including snow plowing with vehicles equipped
with the optional Snow Plow Prep Package (RPO
VYU). But don't change or defeat the snow plow's
ªtripping mechanism.º If you do, it can damage
your snow plow and your vehicle, and it may cause
an air bag inflation.