1999 GMC YUKON Owner's Manual

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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.
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.

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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.
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.

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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.
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 GM 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 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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1-30 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.)
Rear Seat Passengers
It's very important for rear seat passengers to buckle up!
Accident statistics show that unbelted people in the rear
seat are hurt more often in crashes than those who are
wearing safety belts.
Rear passengers who aren't safety belted can be thrown
out of the vehicle in a crash. And they can strike others
in the vehicle who are wearing safety belts.
Rear Seat Outside Passenger Positions

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Lap-Shoulder Belt
The positions next to the windows have lap
-shoulder
belts. Here's how to wear one properly.
1. Pick up the latch plate and pull the belt across you.
Don't let it get twisted.
2. Push the latch plate into the buckle until it clicks.
Pull up on the latch plate to make sure it is secure.When the shoulder belt is pulled out all the way, it
will lock. If it does, let it go back all the way and
start again.
If the belt is not long enough, see ªSafety Belt
Extenderº at the end of this section.
Make sure the release button on the buckle is
positioned so you would be able to unbuckle the
safety belt quickly if you ever had to.
3. To make the lap part tight, pull down on the buckle
end of the belt as you pull up on the shoulder part.

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The lap part of the belt should be worn low and snug on
the hips, just touching the thighs. In a crash, this applies
force to the strong pelvic bones. And you'd be less likely
to slide under the lap belt. If you slid under it, the belt
would apply force at your abdomen. This could cause
serious or even fatal injuries. The shoulder belt should go
over the shoulder and across the chest. These parts of the
body are best able to take belt restraining forces.
The safety belt locks if there's a sudden stop or a crash.
Each position next to the windows has a shoulder belt
height adjuster. Move the shoulder belt height adjuster
to the height that is right for you.

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To move the height adjuster down, push in at the word
PRESS and move the height adjuster to the desired
position. You can move the adjuster up just by pushing up
on the shoulder belt guide. After you move the adjuster to
where you want it, try to move it down without pushing in
to make sure it has locked into position.
Adjust the height so that the shoulder portion of the belt is
centered on your shoulder. The belt should be away from
your face and neck, but not falling off your shoulder.
CAUTION:
You can be seriously hurt if your shoulder belt is
too loose. In a crash, you would move forward
too much, which could increase injury. The
shoulder belt should fit against your body.
To unlatch the belt, just push the button on the buckle.

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Rear Safety Belt Comfort Guides for
Children and Small Adults
Rear shoulder belt comfort guides will provide added
safety belt comfort for children who have outgrown
child restraints and for small adults. When installed on a
shoulder belt, the comfort guide pulls the belt away
from the neck and head.
There is one guide for each outside passenger position in
the rear seat. To provide added safety belt comfort for
children who have outgrown child restraints and for
smaller adults, the comfort guides may be installed on
the shoulder belts. Here's how to install a comfort guide
and use the safety belt:
1. Remove the guide from its storage clip on the side of
the seatback.