1999 GMC YUKON gas type

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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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If your vehicle is certified to meet California Emission
Standards (indicated on the underhood emission control
label), it is designed to operate on fuels that meet
California specifications. If such fuels are not available
in states adopting California emissions standards, your
vehicle will operate satisfactorily on fuels meeting
federal specifications, but emission control system
performance may be affected. The malfunction indicator
lamp on your instrument panel may turn on and/or your
vehicle may fail a smog
-check test. If this occurs, return
to your authorized GMC dealer for diagnosis to
determine the cause of failure. In the event it is
determined that the cause of the condition is the type of
fuels used, repairs may not be covered by your warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane
-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask your service station operator whether or not
his fuel contains MMT. General Motors does not
recommend the use of such gasolines. If fuels containing
MMT are used, spark plug life may be reduced and your
emission control system performance may be affected.
The malfunction indicator lamp on your instrument
panel may turn on. If this occurs, return to your
authorized GMC dealer for service.To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent deposits from forming in your engine and fuel
system, allowing your emission control system to
function properly. Therefore, you should not have to add
anything to the fuel. In addition, gasolines containing
oxygenates, such as ethers and ethanol, and
reformulated gasolines may be available in your area to
contribute to clean air. General Motors recommends that
you use these gasolines, particularly if they comply with
the specifications described earlier.
NOTICE:
Your vehicle was not designed for fuel that
contains methanol. Don't use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn't
be covered under your warranty.

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CAUTION:
If you get gasoline on yourself and then
something ignites it, you could be badly burned.
Gasoline can spray out on you if you open the
fuel filler cap too quickly. This spray can happen
if your tank is nearly full, and is more likely in
hot weather. Open the fuel filler cap slowly and
wait for any ªhissº noise to stop. Then unscrew
the cap all the way.
Be careful not to spill gasoline. Clean gasoline from
painted surfaces as soon as possible. See ªCleaning the
Outside of Your Vehicleº in the Index.When you put the cap back on, turn it to the right
(clockwise) until you hear a clicking sound. Make sure
you fully install the cap. The diagnostic system can
determine if the fuel cap has been left off or improperly
installed. This would allow fuel to evaporate into the
atmosphere. See ªMalfunction Indicator Lampº in
the Index.
NOTICE:
If you need a new cap, be sure to get the right type.
Your dealer can get one for you. If you get the
wrong type, it may not fit properly. This may cause
your malfunction indicator lamp to light and your
fuel tank and emissions system may be damaged.
See ªMalfunction Indicator Lampº in the Index.

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Bulb Replacement
Before you replace any bulbs, be sure that all the lamps
are off and the engine isn't running. For the proper bulb
type, see ªReplacement Bulbsº in the Index. For any
bulb changing procedure not listed in this section,
contact your dealer's service department.
Halogen Bulbs
CAUTION:
Halogen bulbs have pressurized gas inside and
can burst if you drop or scratch the bulb. You or
others could be injured. Be sure to read and
follow the instructions on the bulb package.
Headlamps
Parking/Turn Signal Lamp Removal
1. Remove the two phillips-head screws on the side of
the parking/turn signal bulb assembly. The
parking/turn signal assembly must be removed to
provide clearance for headlamp removal.
2. Pull the parking/turn signal assembly toward the side
of the vehicle until the tabs are out of the grille.