1999 GMC YUKON wheel

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Your vehicle has a light that
comes on as a reminder to
buckle up. (See ªSafety Belt
Reminder Lightº in
the Index.)
In most states and Canadian provinces, the law says to
wear safety belts. Here's why: They work.
You never know if you'll be in a crash. If you do have a
crash, you don't know if it will be a bad one.
A few crashes are mild, and some crashes can be so
serious that even buckled up a person wouldn't survive.
But most crashes are in between. In many of them,
people who buckle up can survive and sometimes walk
away. Without belts they could have been badly hurt
or killed.
After more than 30 years of safety belts in vehicles, the
facts are clear. In most crashes buckling up does
matter ... a lot!Why Safety Belts Work
When you ride in or on anything, you go as fast as
it goes.
Take the simplest vehicle. Suppose it's just a seat
on wheels.

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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.How the Air Bag System Works
Where are the air bags?
The driver's air bag is in the middle of the
steering wheel.

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The right front passenger's air bag is in the instrument
panel on the passenger's side.
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.

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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.

2-
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Section 2 Features and Controls
Here you can learn about the many standard and optional features on your vehicle, and information on starting,
shifting and braking. Also explained are the instrument panel and the warning systems that tell you if everything is
working properly
-- and what to do if you have a problem.
2
-2 Keys
2
-3 Door Locks
2
-6 Keyless Entry System
2
-11 Rear Doors
2
-13 Theft
2
-13 Theft-Deterrent System
2
-16 Feature Customization
2
-20 Passlock

2-20 New Vehicle ªBreak-Inº
2
-21 Ignition Positions
2
-22 Starting Your Engine
2
-24 Engine Coolant Heater (If Equipped)
2
-25 Automatic Transmission Operation
2
-28 Four-Wheel Drive
2
-32 Parking Brake
2
-33 Shifting Into Park (P)
2
-35 Shifting Out of Park (P)
2
-36 Parking Over Things That Burn
2
-36 Engine Exhaust2
-37 Running Your Engine While You're Parked
2
-38 Locking Rear Axle
2
-38 Windows
2
-39 Horn
2
-39 Tilt Wheel
2
-40 Multifunction Lever
2
-46 Exterior Lamps
2
-49 Interior Lamps
2
-51 Mirrors
2
-55 Storage Compartments
2
-61 Ashtrays and Cigarette Lighter
2
-63 Sun Visors
2
-63 Universal Transmitter
2
-67 Cellular Telephone (If Equipped)
2
-67 OnStar
System (If Equipped)
2
-68 Instrument Panel
2
-70 Instrument Panel Cluster
2
-72 Warning Lights, Gages and Indicators

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Theft
Vehicle theft is big business, especially in some cities.
Although your vehicle has a number of theft
-deterrent
features, we know that nothing we put on it can make it
impossible to steal. However, there are ways you
can help.
Key in the Ignition
If you leave your vehicle with the keys inside, it's an
easy target for joy riders or professional thieves
-- so
don't do it.
When you park your vehicle and open the driver's door,
you'll hear a chime reminding you to remove your key
from the ignition and take it with you. Always do this.
Your steering wheel will be locked, and so will your
ignition and transmission. Also remember to lock
the doors.
Parking at Night
Park in a lighted spot, close all windows and lock your
vehicle. Remember to keep your valuables out of sight.
Put them in a storage area, or take them with you.
Parking Lots
If you park in a lot where someone will be watching
your vehicle, it's best to lock it up and take your keys.
But what if you have to leave your ignition key? What if
you have to leave something valuable in your vehicle?

Put your valuables in a storage area, like your
glove box.

Lock all the doors except the driver's.
Theft-Deterrent System
Your vehicle has a theft-deterrent alarm system. Once
armed, the system will sound the horn and flash the
parking lamps if the vehicle is tampered with.
Opening the doors may activate the alarm. See
ªDisarming the Systemº later in this section for further
information on turning the system off.