brakes GMC SIERRA DENALI 2003 User Guide

Anti-lock Brake System
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’s a problem with
the anti-lock brake system,
this warning light will stay on. See
Anti-Lock
Brake
System Warning
Light on page
3-35.
Along with ABS, your vehicle has a Dynamic Rear
Proportioning (DRP) system.
If there’s 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. Let’s
say the road is wet and you’re driving safely.
Suddenly, an animal jumps out in front of you.
You slam
on the brakes and continue braking. Here’s 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.
4-7

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. Remember:
Anti-lock doesn’t 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 won’t 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
Don’t pump the brakes. Just hold the brake pedal down
firmly 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, you can steer and brake at the same
time. In many emergencies, steering can help you more
than even the very best braking.
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.
4-8

Your vehicle can perform very well in emergencies like
these. First apply your brakes.
See
Braking on page 4-6. 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.
QUADRASTEERTM
The QUADRASTEERTM System has a control and
diagnostic module that monitors and records current
system status and operational information.
If your vehicle is equipped with the 4 Wheel Steer
system it has the ability to steer the vehicle with all four
wheels.
Once the
4 Wheel Steer mode is selected, it is
recommended
to leave the vehicle in this mode at all
times, and during all driving and weather conditions.
You can select this mode at any speed, however,
if you
are turning the system will not engage until the turn
is complete.
The 4 Wheel Steer system is equipped with three
different driving modes:
Two wheel steering (2)
Four wheel steering (4)
Four wheel steering with a trailer mode (q )
4-1 0

a
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 lane change 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.
Don’t overtake a slowly moving vehicle too rapidly.
Even though the brake lamps are not flashing, it may
be slowing down or starting to turn.
If you’re 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’s review what driving experts say about what
happens when the three control systems (brakes,
steering and acceleration) don’t have enough friction
where the tires meet the road to do what the driver
has asked.
In any emergency, don’t give up. Keep trying
to steer
and constantly seek an escape route or area of
less danger.
Skidding
In a skid, a driver can lose control of the vehicle.
Defensive drivers avoid most skids by taking reasonable
care suited
to existing conditions, and by not
“overdriving” those conditions. But skids are always
possible.
The three types of skids correspond to your vehicle’s
three control systems. In the braking skid, your wheels
aren’t rolling. In the steering or cornering skid, too
much speed or steering
in a curve causes tires to slip
and lose cornering force. And in the acceleration
skid, too much throttle causes the driving wheels
to spin.
A cornering skid is best handled by easing your foot
off
the accelerator pedal.
If your vehicle starts to slide, ease your foot off the
accelerator pedal and quickly steer the way you want
the vehicle
to go. If you start steering quickly enough,
your vehicle may straighten out. Always be ready
for a second skid
if it occurs.
Of course, traction is reduced when water, snow, ice,
gravel or other material
is on the road. For safety, you’ll
want to slow down and adjust your driving
to these
conditions.
It is important to slow down on slippery
surfaces because stopping distance will be longer and
vehicle control more limited.
4-1 5

Q: Suppose, after stalling, I try to back down the hill
A: Set the parking brake, put your transmission in
PARK (P) and turn
off the engine. Leave the
vehicle and go get some help. Exit
on the uphill
side and stay clear of the path the vehicle would
take
if it rolled downhill.
and decide
I just can’t
do it. What should I do?
Driving Downhill
When off-roading takes you downhill, you’ll want to
consider a number of things:
How steep is the downhill? Will I be able to maintain
vehicle control?
What’s the surface like? Smooth? Rough? Slippery?
Hard-packed dirt? Gravel?
0 Are there hidden surface obstacles? Ruts? Logs?
What’s at the bottom of the hill? Is there a hidden
Boulders?
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 won’t hate to do all the work. Descend slowly,
keeping your vehicle under control at all times. Heavy
braking when going down a
h 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
A: Yes! These are important because if you ignore
driving
down a hill?
0
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’s not too
steep to drive down may be too steep to drive
across. You could roll over
if you don’t 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.
4-24

Q: Am I likely to stall when going downhill?
A: It’s much more likely to happen going uphill. But if it
* Stop your vehicle by applying the regular brakes.
happens
going downhill, here’s what to do.
Apply the parking brake.
Shift to PARK (P) and, while still braking, restart the
Shift back to a low gear, release the parking brake,
engine.
and
drive straight down.
0 If the engine won’t start, get out and get help.
Driving Across an Incline
Sooner or later, an off-road trail will probably go across
the incline of a hill. If this happens, you have to
decide whether to try to drive across the incline. Here
are some things to consider:
A hill that can be driven straight up or down may be
too steep to drive across. When you go straight up or
down a hill, the length of the wheel bas (the distance
from the front wheels to the rear wheels) reduces the
likelihood the vehicle will tumble end over end. But
when you drive across an incline, the much more
narrow track width (the distance between the left and
right wheels) may not prevent the vehicle from tilting
and rolling over. Also, driving across an incline puts
more wight on the downhill wheels. This could cause
a downhill slide or a rollover.
0
0
Surface conditions can be a problem when you drive
across a hill. Loose gravel, muddy spots, or even wet
grass can cause your tires to slip sideways, downhill.
If the vehicle slips sideways, it can hit something that
will trip it (a rock,
a rut, etc.) and roll over.
Hidden obstacles can make the steepness of the
incline even worse.
If you drive across a rock with the
uphill wheels, or
if the downhill wheels drop into a rut
or depression, your vehicle can tilt even more.
For reasons like these, you need to decide carefully
whether to try to drive across an incline. Just because the
trail goes across the incline doesn’t mean you hat to drive
it. The last vehicle to try it might have rolled over.
Driving across an incline that’s too steep will
make your vehicle roll over. You could be
seriously injured or killed.
If you have any
doubt about the steepness
of the incline, don’t
drive across it. Find another route instead.
4-25

If the water isn’t too deep, drive slowly through it. At
faster speeds, water splashes on your ignition system
and your vehicle can stall. Stalling can also occur
if you
get your tailpipe under water. And, as long as your
tailpipe is under water, you’ll never be able to start your
engine. When you go through water, remember that
when your brakes get wet, it may take you longer
+- stop.
,,jving thr,,gh rushing water can be
dangerous. Deep water can sweep your vehicle
downstream and you and your passengers
could drown. If it’s only shallow water, it can
still wash away the ground from under your
tires, and you could lose traction and roll the
water.
~ vehicle over. Don’t drive through rushing
I
After Off-Road Driving
Remove any brush or debris that has collected on the
underbody, chassis or under the hood. These
accumulations can be a fire hazard.
After operation
in mud or sand, have the brake linings
cleaned and checked. These substances can cause
glazing and uneven braking. Check the body structure,
steering, suspension, wheels, tires and exhaust
system for damage. Also, check the fuel lines and
cooling system for any leakage.
Your vehicle will require more frequent service due
to
off-road use. Refer to the Maintenance Schedule
for additional information.
See
Driving in Rain and on Wet Roads on page 4-30 for
more information on driving through water.
4-28

The heavier the rain, the harder it is to see. Even if your
windshield wiper blades are in good shape, a heavy
rain can make it harder to see road signs and
traffic signals, pavement markings, the edge of the road
and even people walking.
It's wise to keep your wiping equipment in good shape
and keep your windshield washer tank filled with
washer fluid. Replace your windshield wiper inserts
when they show signs of streaking or missing areas on
the windshield, or when strips of rubber start to
separate from the inserts. Driving too fast through large
water puddles or even
going through some car washes can cause problems,
too. The water may affect your brakes. Try to avoid
puddles. But
if you can't, try to slow down before you
hit them.
Wet brakes
4 1 cause accidents. They won't
work as well in a quick stop and may cause
pulling
to one side. You could lose control of
the vehicle.
After driving through a large puddle of water
or a car wash, apply your brake pedal lightly
until your brakes work normally.
4-3 1

If you drive regularly in steep country, or if you’re
planning to visit there, here are some tips that can make
your trips safer and more enjoyable. See
Operating
Your All-Wheel-Drive Vehicle
Off Paved Roads on
page
4-16 for information about driving off-road.
Keep your vehicle in good shape. Check all fluid
levels and also the brakes, tires, cooling system
and transmission. These parts can work hard
on mountain roads.
Know how to go down hills. The most important
thing to know is this: let your engine do some of
the slowing down. Shift to a lower gear when you go
down a steep or long hill.
If you don’t I R down, your -____ 3s COL- ge-
so hot that they wouldn’t work well. You would
then have poor braking or even none going
down a hill. You could crash. Shift down to let
your engine assist your brakes on a steep downhill slope. Coasting
UVwnlll..
..I NEUTRAL (N) G. .... h the
ignition
off is dangerous. Your brakes will have
to do all the work
of slowing down. They could
get
so hot that they wouldn’t work well. You
would then have poor braking or even none
going down a
hill. You could crash. Always
have your engine running and your vehicle in
gear when you go downhill.
Know how to go uphill. You may want to shift down to
a lower gear. The lower gears help cool your engine
and transmission, and you can climb the hill better.
roads in hills or mountains. Don’t swing wide or cut
across the center of the road. Drive at speeds that let
you stay in your own lane.
As you go over the top of a hill, be alert. There could
be something in your lane, like a stalled car or an
accident.
You may see highway signs on mountains that warn
of special problems. Examples are long grades,
passing or no-passing zones, a falling rocks area or
winding roads. Be alert to these and take appropriate
action.
Stay in your own lane when driving on two-lane
4-37

Driving on Snow or Ice
Most of the time, those places where your tires meet
the road probably have good traction. the
least traction of all. You can get wet ice when it’s
about freezing (32°F; OOC) and freezing rain begins
to fall. Try to avoid driving on wet ice until salt and sand
crews can get there.
However,
if there is snow or ice between your tires and Whatever the condition - smooth ice, packed, blowing
the road, you can have a very slippery situation.
You’ll have a lot less traction or “grip” and will need to
be very careful. Accelerate gently. Try not to break the fragile traction.
If
or loose snow - drive with caution.
you accelerate too fast, the drive wheels will spin and
polish the surface under the tires even more.
m
What’s the worst time for this? “Wet ice.” Very cold
snow or ice can be slick and hard to drive on. But wet
ice can be even more trouble because it may offer Your
anti-lock brakes improve your vehicle’s stability
when you make a hard stop on a slippery road.
Even though you have an anti-lock braking system,
you’ll want to begin stopping sooner than you would on
dry pavement. See
Braking on page 4-6.
Allow greater following distance on any slippery
road.
0 Watch for slippery spots. The road might be fine
until you hit a spot that’s covered with ice. On
an otherwise clear road, ice patches may appear
in
shaded areas where the sun can’t reach: around
clumps
of trees, behind buildings or under bridges.
Sometimes the surface of a curve or an overpass
may remain icy when the surrounding roads
are clear.
If you see a patch of ice ahead of you,
brake before you are on it. Try not to brake
while you’re actually on the ice, and avoid sudden
steering maneuvers.
4-39