2005 GMC YUKON brakes

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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The StabiliTrak®button is
located on the instrument
panel.
StabiliTrak
®and part of the traction control system can
be turned off or back on by pressing the StabiliTrak®
button. All-wheel drive vehicles must be in all-wheel
drive mode to turn the system on or off.
Four-wheel-drive vehicles must be in 2HI, 4HI
or AUTO 4WD to turn the system on or off.
When the system is turned off, the traction off light will
illuminate, and the STABILITY SYS DISABLED
message will appear on the DIC to warn the driver that
both the stability system and part of the traction
control system are disabled. Your vehicle will still have
brake-traction control when StabiliTrak
®is off, but
will not be able to use the engine speed management
system. See “Traction Control Operation” next for
more information.
When the StabiliTrak
®system has been turned off, you
may still hear system noises as a result of the
brake-traction control coming on.It is recommended to leave the system on for normal
driving conditions, but it may be necessary to turn the
system off if your vehicle is stuck in sand, mud, ice or
snow, and you want to “rock” your vehicle to attempt to
free it. It may also be necessary to turn off the system
when driving in extreme off-road conditions where high
wheel spin is required. SeeIf Your Vehicle is Stuck in
Sand, Mud, Ice or Snow on page 4-49.
When the transfer case is in 4LO, the stability system is
automatically disabled, and the STABILITY SYS
DISABLED message will appear on the DIC. In 4LO,
the StabiliTrak
®button only turns the traction control
system on and off.
Traction Control Operation
The traction control system is part of the StabiliTrak®
system. Traction control limits wheel spin by reducing
engine power to the wheels (engine speed
management) and by applying brakes to each individual
wheel (brake-traction control) as necessary.
The traction control system is enabled automatically
when you start your vehicle, and it will activate
and display the TRACTION ACTIVE message in the
Driver Information Center (DIC) if it senses that any of
the wheels are spinning or beginning to lose traction
while driving. If you turn off StabiliTrak
®, only the
brake-traction control portion of traction control will work.
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The engine speed management will be disabled. In this
state, engine power is not reduced automatically and
the driven wheels can spin more freely. This can cause
the brake-traction control to activate constantly. For
more information on the traction active message, see
Driver Information Center (DIC) on page 3-54.
Notice:If the traction off light comes on due to
heavy braking and/or because the traction control
system has been continuously active, do not
allow the wheel(s) of one axle to spin excessively.
If you do, you may be causing damage to the
transfer case. This could lead to costly repairs not
covered by your warranty.
If the brake traction-control system activates constantly
or if the brakes have heated up due to high speed
braking, brake traction-control will be disabled and the
TRACTION SYS LIMITED message will be displayed. In
the limited mode, the traction-control system will only
use engine traction-control and is limited in it’s ability to
provide optimal performance since the system will
not utilize brake traction-control to control slip on the
drive wheels. The system will return to normal operation
after the brakes have cooled. This can take up to two
minutes or longer depending on brake usage.Notice:If you allow the wheel(s) of one axle to spin
excessively while the traction off, ABS and brake
warning lights and the SERVICE STABILITY
message are displayed, you could damage the
transfer case. The repairs would not be covered by
your warranty. Reduce engine power and do not
spin the wheel(s) excessively while these lights and
this message are displayed.
The traction control system may activate on dry or
rough roads or under conditions such as heavy
acceleration while turning or abrupt upshifts/downshifts
of the transmission. When this happens, you may
notice a reduction in acceleration, or may hear a noise
or vibration. This is normal.
If your vehicle is in cruise control when the system
activates, the STABILITY SYS ACTIVE message will
appear on the Driver Information Center (DIC), and the
cruise control will automatically disengage. When road
conditions allow you to use cruise again, you may
re-engage the cruise control. SeeCruise Control on
page 3-11.
StabiliTrak
®may also turn off automatically if it
determines that a problem exists with the system.
If the problem does not clear itself after restarting
the vehicle, you should see your dealer for service.
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Steering in Emergencies
There are times when steering can be more effective
than braking. For example, you come over a hill and nd
a truck stopped in your lane, or a car suddenly pulls
out from nowhere, or a child darts out from between
parked cars and stops right in front of you. You can
avoid these problems by braking — if you can stop in
time. But sometimes you cannot; there is not room.
That is the time for evasive action — steering around the
problem.
Your vehicle can perform very well in emergencies like
these. First apply your brakes.
SeeBraking on page 4-5. It is better to remove as much
speed as you can from a possible collision. Then
steer around the problem, to the left or right depending
on the space available.An emergency like this requires close attention and a
quick decision. If you are holding the steering wheel at
the recommended 9 and 3 o’clock positions, you
can turn it a full 180 degrees very quickly without
removing either hand. But you have to act fast, steer
quickly, and just as quickly straighten the wheel
once you have avoided the object.
The fact that such emergency situations are always
possible is a good reason to practice defensive driving
at all times and wear safety belts properly.
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Do not get too close to the vehicle you want to
pass while you are awaiting an opportunity. For one
thing, following too closely reduces your area of
vision, especially if you are following a larger
vehicle. Also, you will not have adequate space if
the vehicle ahead suddenly slows or stops.
Keep back a reasonable distance.
When it looks like a chance to pass is coming up,
start to accelerate but stay in the right lane and
do not get too close. Time your move so you will be
increasing speed as the time comes to move into
the other lane. If the way is clear to pass, you
will have a running start that more than makes up
for the distance you would lose by dropping
back. And if something happens to cause you to
cancel your pass, you need only slow down
and drop back again and wait for another
opportunity.
If other vehicles are lined up to pass a slow vehicle,
wait your turn. But take care that someone is not
trying to pass you as you pull out to pass the slow
vehicle. Remember to glance over your shoulder
and check the blind spot.
Check your mirrors, glance over your shoulder and
start your left lane change signal before moving out
of the right lane to pass. When you are far
enough ahead of the passed vehicle to see its front
in your inside mirror, activate your right lanechange signal and move back into the right lane.
Remember that if your right outside mirror is convex,
the vehicle you just passed may seem to be
farther away from you than it really is.
Try not to pass more than one vehicle at a time on
two-lane roads. Reconsider before passing the
next vehicle.
Do not overtake a slowly moving vehicle too rapidly.
Even though the brake lamps are not ashing, it
may be slowing down or starting to turn.
If you are being passed, make it easy for the
following driver to get ahead of you. Perhaps
you can ease a little to the right.
Loss of Control
Let us review what driving experts say about what
happens when the three control systems — brakes,
steering, and acceleration — do not have enough friction
where the tires meet the road to do what the driver
has asked.
In any emergency, do not give up. Keep trying to steer
and constantly seek an escape route or area of less
danger.
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Are there hidden surface obstacles? Ruts? Logs?
Boulders?
What is at the bottom of the hill? Is there a hidden
creek bank or even a river bottom with large rocks?
If you decide you can go down a hill safely, then try to
keep your vehicle headed straight down, and use a
low gear. This way, engine drag can help your brakes
and they will not have to do all the work. Descend
slowly, keeping your vehicle under control at all times.
{CAUTION:
Heavy braking when going down a hill can
cause your brakes to overheat and fade. This
could cause loss of control and a serious
accident. Apply the brakes lightly when
descending a hill and use a low gear to keep
vehicle speed under control.
Q:Are there some things I should not do when
driving down a hill?
A:Yes! These are important because if you ignore
them you could lose control and have a serious
accident.
When driving downhill, avoid turns that take you
across the incline of the hill. A hill that is not too
steep to drive down may be too steep to drive
across. You could roll over if you do not drive
straight down.
Never go downhill with the transmission in
NEUTRAL (N). This is called “free-wheeling.”
Your brakes will have to do all the work and could
overheat and fade.
Q:Am I likely to stall when going downhill?
A:It is much more likely to happen going uphill. But if
it happens going downhill, here is what to do.
1. Stop your vehicle by applying the regular brakes.
Apply the parking brake.
2. Shift to PARK (P) and, while still braking, restart the
engine.
3. Shift back to a low gear, release the parking brake,
and drive straight down.
4. If the engine will not start, get out and get help.
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