2005 GMC YUKON Owner's Manual

Many adults — by some estimates, nearly half the adult
population — choose never to drink alcohol, so they
never drive after drinking. For persons under 21,
it is against the law in every U.S. state to drink alcohol.
There are good medical, psychological and
developmental reasons for these laws.
The obvious way to eliminate the leading highway
safety problem is for people never to drink alcohol and
then drive. But what if people do? How much is
“too much” if someone plans to drive? It is a lot less
than many might think. Although it depends on
each person and situation, here is some general
information on the problem.
The Blood Alcohol Concentration (BAC) of someone
who is drinking depends upon four things:
The amount of alcohol consumed
The drinker’s body weight
The amount of food that is consumed before and
during drinking
The length of time it has taken the drinker to
consume the alcohol
According to the American Medical Association, a
180 lb (82 kg) person who drinks three 12 ounce (355 ml)
bottles of beer in an hour will end up with a BAC of about
0.06 percent. The person would reach the same BAC bydrinking three 4 ounce (120 ml) glasses of wine or
three mixed drinks if each had 1-1/2 ounces (45 ml) of
liquors like whiskey, gin, or vodka.
It is the amount of alcohol that counts. For example, if
the same person drank three double martinis (3 ounces
or 90 ml of liquor each) within an hour, the person’s
BAC would be close to 0.12 percent. A person
who consumes food just before or during drinking will
have a somewhat lower BAC level.
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There is a gender difference, too. Women generally
have a lower relative percentage of body water
than men. Since alcohol is carried in body water, this
means that a woman generally will reach a higher BAC
level than a man of her same body weight will when
each has the same number of drinks.
The law in most U.S. states, and throughout Canada,
sets the legal limit at 0.08 percent. In some other
countries, the limit is even lower. For example, it is
0.05 percent in both France and Germany. The
BAC limit for all commercial drivers in the United States
is 0.04 percent.
The BAC will be over 0.10 percent after three to
six drinks (in one hour). Of course, as we have seen,
it depends on how much alcohol is in the drinks,
and how quickly the person drinks them.
But the ability to drive is affected well below a BAC of
0.10 percent. Research shows that the driving skills
of many people are impaired at a BAC approaching
0.05 percent, and that the effects are worse at night. All
drivers are impaired at BAC levels above 0.05 percent.Statistics show that the chance of being in a collision
increases sharply for drivers who have a BAC of
0.05 percent or above. A driver with a BAC level of
0.06 percent has doubled his or her chance of having a
collision. At a BAC level of 0.10 percent, the chance
of this driver having a collision is 12 times greater; at a
level of 0.15 percent, the chance is 25 times greater!
The body takes about an hour to rid itself of the alcohol in
one drink. No amount of coffee or number of cold
showers will speed that up. “I will be careful” is not the
right answer. What if there is an emergency, a need to
take sudden action, as when a child darts into the street?
A person with even a moderate BAC might not be able to
react quickly enough to avoid the collision.
There is something else about drinking and driving that
many people do not know. Medical research shows
that alcohol in a person’s system can make crash
injuries worse, especially injuries to the brain, spinal
cord, or heart. This means that when anyone who has
been drinking — driver or passenger — is in a crash,
that person’s chance of being killed or permanently
disabled is higher than if the person had not been
drinking.
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{CAUTION:
Drinking and then driving is very dangerous.
Your reexes, perceptions, attentiveness, and
judgment can be affected by even a small
amount of alcohol. You can have a
serious — or even fatal — collision if you drive
after drinking. Please do not drink and drive or
ride with a driver who has been drinking. Ride
home in a cab; or if you are with a group,
designate a driver who will not drink.
Control of a Vehicle
You have three systems that make your vehicle go where
you want it to go. They are the brakes, the steering, and
the accelerator. All three systems have to do their work at
the places where the tires meet the road.
Sometimes, as when you are driving on snow or ice, it is
easy to ask more of those control systems than the tires
and road can provide. That means you can lose control
of your vehicle. SeeTraction Assist System (TAS)
on page 4-8.
Braking
Braking action involves perception time and
reaction time.
First, you have to decide to push on the brake pedal.
That is perception time. Then you have to bring up your
foot and do it. That is reaction time.
Average reaction time is about three-fourths of a
second. But that is only an average. It might be less
with one driver and as long as two or three seconds or
more with another. Age, physical condition, alertness,
coordination, and eyesight all play a part. So do alcohol,
drugs, and frustration. But even in three-fourths of a
second, a vehicle moving at 60 mph (100 km/h) travels
66 feet (20 m). That could be a lot of distance in an
emergency, so keeping enough space between
your vehicle and others is important.
And, of course, actual stopping distances vary greatly
with the surface of the road, whether it is pavement
or gravel; the condition of the road, whether it is
wet, dry, or icy; tire tread; the condition of your brakes;
the weight of the vehicle; and the amount of brake
force applied.
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Avoid needless heavy braking. Some people drive in
spurts — heavy acceleration followed by heavy
braking — rather than keeping pace with traffic. This is
a mistake. Your brakes may not have time to cool
between hard stops. Your brakes will wear out much
faster if you do a lot of heavy braking. If you keep pace
with the traffic and allow realistic following distances,
you will eliminate a lot of unnecessary braking.
That means better braking and longer brake life.
If your engine ever stops while you are driving, brake
normally but do not pump your brakes. If you do,
the pedal may get harder to push down. If your engine
stops, you will still have some power brake assist.
But you will use it when you brake. Once the power
assist is used up, it may take longer to stop and
the brake pedal will be harder to push.Anti-Lock Brake System (ABS)
Your vehicle has anti-lock brakes. ABS is an advanced
electronic braking system that will help prevent a
braking skid.
When you start your engine and begin to drive away,
your anti-lock brake system will check itself. You
may hear a momentary motor or clicking noise while
this test is going on. This is normal.
If there is a problem with
the anti-lock brake system,
this warning light will
stay on. SeeAnti-Lock
Brake System Warning
Light on page 3-44.
Along with ABS, your vehicle has a Dynamic Rear
Proportioning (DRP) system. If there is a DRP problem,
both the brake and ABS warning lights will come on
accompanied by a 10-second chime. The lights and
chime will come on each time the ignition is turned on
until the problem is repaired. See your dealer for service.
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Let us say the road is wet and you are driving safely.
Suddenly, an animal jumps out in front of you. You slam
on the brakes and continue braking. Here is what
happens with ABS:
A computer senses that wheels are slowing down.
If one of the wheels is about to stop rolling, the computer
will separately work the brakes at each front wheel
and at both rear wheels.The anti-lock system can change the brake pressure
faster than any driver could. The computer is
programmed to make the most of available tire and road
conditions. This can help you steer around the obstacle
while braking hard.
As you brake, your computer keeps receiving updates
on wheel speed and controls braking pressure
accordingly.
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Remember: Anti-lock does not change the time you
need to get your foot up to the brake pedal or always
decrease stopping distance. If you get too close to
the vehicle in front of you, you will not have time to apply
your brakes if that vehicle suddenly slows or stops.
Always leave enough room up ahead to stop, even
though you have anti-lock brakes.
Using Anti-Lock
Do not pump the brakes. Just hold the brake pedal
down rmly and let anti-lock work for you. You may feel
the brakes vibrate, or you may notice some noise,
but this is normal.
Braking in Emergencies
With anti-lock brakes, you can steer and brake at the
same time. In many emergencies, steering can help you
more than even the very best braking.
Traction Assist System (TAS)
Your vehicle may have a Traction Assist System (TAS)
that limits wheel spin. This is especially useful in
slippery road conditions. The system operates only if it
senses that one or both of the rear wheels are
spinning or beginning to lose traction. When this
happens, the system reduces engine power to limit
wheel spin.The traction control system is enabled every time your
vehicle is started. The system will activate if it senses
that any of the wheels are spinning or beginning to lose
traction.
You may hear or feel the system working or notice a
lack of accelerator response, but this is normal.
The Traction Assist System may operate on dry roads
under some conditions. When this happens, you
may notice a reduction in acceleration. This is normal
and doesn’t mean there’s a problem with your vehicle.
Examples of these conditions include a hard
acceleration in a turn, an abrupt upshift or downshift of
the transmission or driving on rough roads.
If your vehicle is in cruise control when the TAS begins
to limit wheel spin, the cruise control will automatically
disengage. When road conditions allow you to safely
use it again, you may re-engage the cruise control.
SeeCruise Control on page 3-11.
When the traction off light
is on, the TAS is off and
will not limit wheel
spin. Adjust your driving
accordingly.
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The traction off light will come on under the following
conditions:
The Traction Assist System is turned off, either by
pressing the TAS on/off button or turning off the
automatic engagement feature of the TAS.
The transmission is in FIRST (1); TAS will not
operate in this gear. This is normal.
The vehicle is driven on an extremely rough road.
When the vehicle leaves the rough surface, slows
down or stops, the light will go off and TAS will
be on again. This is normal.
A Traction Assist System, Anti-Lock Brake System
or engine-related problem has been detected and
the vehicle needs service.
If the vehicle has been driven with the TAS system
on for long periods of time, or if the vehicle has
gone through many high speed braking maneuvers
the system may be automatically disabled. The
system will automatically re-enable after
approximately two minutes of not using the brakes.
The Traction Assist System, as delivered from the
factory, will automatically come on whenever you start
your vehicle. To limit wheel spin, especially in
slippery road conditions, you should always leave the
system on. But you can turn the TAS off if you ever need
to. You should turn the TAS off if your vehicle evergets stuck in sand, mud or snow and rocking the vehicle
is required. SeeRocking Your Vehicle to Get It Out
on page 4-50.
To turn the system on or
off, press the TAS on/off
button located on the
instrument panel.
If you used the button to turn the system off, the traction
off light will come on and stay on. You can turn the
system back on at any time by pressing the button
again. The traction off light should go off.
If desired, you can change the TAS automatic
engagement feature so that the system will not come on
automatically when the engine is started. To do so:
1. Park the vehicle with the ignition off and the
transmission in PARK (P).
2. Turn the ignition to RUN; do not start the engine.
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3. Apply the brake pedal, shift into NEUTRAL (N),
press the accelerator pedal to the oor and then
press the TAS on/off button and hold it down for at
least six seconds.
4. Release the TAS button and both pedals.
5. Turn off the ignition and wait a few seconds.
The next time you start your vehicle, the TAS will not
automatically come on. You can restore the automatic
feature by using the same procedure. Whether the TAS is
set to come on automatically or not, you can always turn
the system on or off by pressing the TAS on/off button.
Locking Rear Axle
If your vehicle has this feature, your locking rear axle
can give you additional traction on snow, mud, ice, sand
or gravel. It works like a standard axle most of the
time, but when one of the rear wheels has no traction
and the other does, this feature will allow the wheel with
traction to move the vehicle.
StabiliTrak®System
Your vehicle may be equipped with the StabiliTrak®
system which combines antilock brake, traction
and stability control systems and helps the driver
maintain directional control of the vehicle in most
driving conditions.When you rst start your vehicle and begin to drive away,
the system performs several diagnostic checks to ensure
there are no problems. You may hear or feel the system
working. This is normal and does not mean there is a
problem with your vehicle. The system should initialize
before the vehicle reaches 20 mph (32 km/h). In some
cases, it may take approximately two miles of driving
before the system initializes.
If the system fails to turn on or activate, the STABILITY
SYS DISABLED or SERVICE STABILITY message
will be displayed. If the vehicle has gone through heavy
acceleration or braking during the rst two miles after
starting your vehicle, the STABILITY SYS DISABLED
message may appear. If this is the case, your
vehicle does not need servicing. Turn your vehicle off
and back on again to reset the system. If either message
appears on the Driver Information Center (DIC), and
your vehicle hasn’t gone through hard acceleration
or braking in the rst two miles, your vehicle should be
taken in for service.
The STABILITY SYS ACTIVE message will appear on
the Driver Information Center (DIC) only when the
system is both on and activated. You may also feel or
hear the system working; this is normal. For more
information on the stability messages, seeDriver
Information Center (DIC) on page 3-54.
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