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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. See
StabiliTrak
®System on page 330.
Adding non-GM accessories can affect your
vehicle’s performance. SeeAccessories and
Modi cations on page 396.
Braking
SeeBrake System Warning Light on page 235.
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.
Adding non-GM accessories can affect your
vehicle’s performance. SeeAccessories and
Modi cations on page 396.Anti-Lock Brake System (ABS)
Your vehicle has the Anti-Lock Brake System
(ABS), an advanced electronic braking system
that will help prevent a braking skid.
When you start your engine and begin to drive
away, ABS 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 ABS, this warning
light will stay on.
SeeAnti-Lock Brake
System Warning
Light on page 237.
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.ABS 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: ABS 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 ABS.
Using ABS
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 ABS, you can steer and brake at the same
time. In many emergencies, steering can help you
more than even the very best braking.
Locking Differential
If your vehicle has this feature, your locking
differential 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 wheels has no traction and the other does,
this feature will allow the wheel with traction
to move the vehicle.
Road Sensing Suspension
The Road Sensing Suspension (RSS) feature
provides superior vehicle ride and handling under
a variety of passenger and loading conditions.
The system is fully automatic and uses a computer
controller to continuously monitor vehicle speed,
wheel to body position, lift/dive and steering
position of the vehicle. The controller then sends
signals to each shock absorber to independently
adjust the damping level to provide the optimum
vehicle ride.
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