1999 GMC C-SERIES brakes

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4-9
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 pulsate, or you may hear air exhausting, but this
is normal.
Braking in Emergencies
At some time, nearly every driver gets into a situation
that requires hard braking.
If you have anti
-lock, you can steer and brake at the
same time. However, if you don't have anti
-lock, your
first reaction
-- to hit the brake pedal hard and hold it
down
-- may be the wrong thing to do. Your wheels can
stop rolling. Once they do, the vehicle can't respond to
your steering. Momentum will carry it in whatever
direction it was headed when the wheels stopped rolling.That could be off the road, into the very thing you were
trying to avoid, or into traffic.
If you don't have anti
-lock, use a ªsqueezeº braking
technique. This will give you maximum braking while
maintaining steering control. You do this by pushing on
the brake pedal with steadily increasing pressure.
In an emergency, you will probably want to squeeze the
brakes hard without locking the wheels. If you hear or
feel the wheels sliding, ease off the brake pedal. This
will help you retain steering control. (If you do have
anti
-lock, it's different: see ªAnti-Lock Brakesº in
the Index.)
In many emergencies, steering can help you more than
even the very best braking.
Steering
Power Steering
If you lose power steering assist because the engine
stops or the system is not functioning, you can steer but
it will take much more effort.
On vehicles with hydraulic brakes, the power steering
and main hydraulic brake system both use the power
steering pump. See ªHydraulic Brake Systemsº in
the Index.
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4-10 Steering Tips
Driving on Curves
It's important to take curves at a reasonable speed.
A lot of the ªdriver lost controlº accidents mentioned on
the news happen on curves. Here's why:
Experienced driver or beginner, each of us is subject to
the same laws of physics when driving on curves. The
traction of the tires against the road surface makes it
possible for the vehicle to change its path when you turn
the front wheels. If there's no traction, inertia will keep
the vehicle going in the same direction. If you've ever
tried to steer a vehicle on wet ice, you'll understand this.
The traction you can get in a curve depends on the
condition of your tires and the road surface, the angle
at which the curve is banked, and your speed. While
you're in a curve, speed is the one factor you
can control.
Suppose you're steering through a sharp curve. Then
you suddenly apply the brakes. Both control
systems
-- steering and braking -- have to do their
work where the tires meet the road. Unless you have
four
-wheel anti-lock brakes, adding the hard braking
can demand too much of those places. You can
lose control.The same thing can happen if you're steering through a
sharp curve and you suddenly accelerate. Those two
control systems
-- steering and acceleration -- can
overwhelm those places where the tires meet the road
and make you lose control.
What should you do if this ever happens? Ease up on the
brake or accelerator pedal, steer the vehicle the way you
want it to go, and slow down.
Speed limit signs near curves warn that you should
adjust your speed. Of course, the posted speeds are
based on good weather and road conditions. Under less
favorable conditions you'll want to go slower.
If you need to reduce your speed as you approach a
curve, do it before you enter the curve, while your front
wheels are straight ahead.
This is especially important with a tractor
-trailer. Try to
adjust your speed so you can ªdriveº through the curve.
Maintain a reasonable, steady speed. Wait to accelerate
until you are out of the curve, and then accelerate gently
into the straightaway.
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4-11 Steering in Emergencies
There are times when steering can be more effective
than braking. For example, you come over a hill and
find 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 can't; there isn't room. That's
the time for evasive action
-- steering around
the problem.
In emergencies like these, first apply your brakes
-- but
unless you have anti
-lock, not enough to lock your
wheels. (See ªBraking in Emergenciesº earlier in this
section.) 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. If your vehicle has anti
-lock brakes, you don't
need to release the brakes to maintain steering control.
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 may be
able to turn it just enough to miss the object without
removing either hand. But you must act fast, steering
precisely. The more sharply you turn, the greater the
chance of a skid, a rollover or a ªjackknifeº with a
tractor
-trailer. 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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4-14
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 ªoverdrivingº
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 and an acceleration skid are
usually best handled by easing your foot off the
accelerator pedal.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.
While driving on a surface with reduced traction, try
your best to avoid sudden steering, acceleration or
braking (including engine braking by shifting to a lower
gear). See ªDiesel Engine Exhaust Brakeº in the Index
for information about using the exhaust brake on
slippery surfaces. Any sudden changes could cause the
tires to slide. You may not realize the surface is slippery
until your vehicle is skidding. Learn to recognize
warning clues
-- such as enough water, ice or packed
snow on the road to make a ªmirrored surfaceº
-- and
slow down when you have any doubt.
If you have the anti
-lock braking system, remember: It
helps avoid only the braking skid. If you do not have
anti
-lock, then in a braking skid (where the wheels are
no longer rolling), release enough pressure on the brakes
to get the wheels rolling again. This restores steering
control. Push the brake pedal down steadily when you
have to stop suddenly. As long as the wheels are rolling,
you will have steering control.
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4-17
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 vehicle 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.
CAUTION:
Wet brakes can 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 vehicle wash, apply your brake pedal lightly
until your brakes work normally.
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4-22
Hill and Mountain Roads
Driving on steep hills or mountains is different from
driving in flat or rolling terrain.Here are some tips that can make your drive through
steep country safer:

Keep the 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.
CAUTION:
If you don't shift down, your brakes 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. Shift down to let your
engine assist your brakes on a steep
downhill slope.
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4-23
CAUTION:
Coasting downhill in NEUTRAL (N) or with 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. Use lower gears. They help
cool your engine and transmission, and you can
climb the hill better.
Stay in your own lane when driving on two
-lane
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,
winding roads and special truck lanes. Be alert to
these and take appropriate action.
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4-25
What's the worst time for this? ªWet ice.º 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 the
least traction of all. You can get wet ice when it's about
freezing (32
F; 0
C) and freezing rain begins to fall.
Try to avoid driving on wet ice until salt and sand crews
can get there.Whatever the condition
-- smooth ice, packed, blowing
or loose snow
-- drive with caution.
Accelerate gently. Try not to break the fragile traction.
If you accelerate too fast, the drive wheels will spin and
polish the surface under the tires even more.
Unless you have the anti
-lock braking system, you'll
want to brake very gently, too. (If you do have anti
-lock,
see ªAnti
-Lockº in the Index. This system improves
your vehicle's stability when you make a hard stop on a
slippery road.) Whether you have the anti
-lock braking
system or not, you'll want to begin stopping sooner than
you would on dry pavement. Without anti
-lock brakes,
if you feel your vehicle begin to slide, let up on the
brakes a little. Push the brake pedal down steadily to get
the most traction you can.
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