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.
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 (wet, dry, icy); tire
tread; the condition of your brakes; the weight of
the vehicle and the amount of brake force applied.
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.
4-6
Anti-Lock Brake System (ABS)
Your vehicle may have anti-lock brakes. ABS is an
advanced electronic braking system that will help
prevent a braking skid.
If your vehicle has anti-lock brakes, this warning light on
the instrument panel will come on brie y when you
start your vehicle.
When you start your engine, or when you 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, and you may even notice that
your brake pedal moves or pulses a little. This is normal.
If there is a problem with the anti-lock brake system,
the anti-lock brake system warning light will stay on.
SeeAnti-Lock Brake System Warning Light on
page 3-33.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. United States
Canada
4-7
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 do not have anti-lock, your
rst 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 cannot
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 do not have anti-lock, use a “squeeze” braking
technique. This will give you maximum braking while
maintaining steering control. You can 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 youdohave anti-lock,
it is different. SeeAnti-Lock Brake System (ABS) on
page 4-7.
In many emergencies, steering can help you more than
even the very best braking.
Traction Control System (TCS)
Your vehicle may have a traction control system 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 front wheels are spinning or
beginning to lose traction. When this happens,
the system works the front brakes and reduces engine
power to limit wheel spin.
You may feel or hear the system working, but this is
normal. Leave the system on during ordinary driving so
that it can operate when needed. When the ignition
is turned to ON, the system automatically turns on.
This light should come on
brie y when you start the
engine. If it stays on or
comes on while you
are driving, there is a
problem with your traction
control system.
4-9
The TRAC OFF button
is located to the left
of the steering wheel
below the instrument
panel cluster.
When getting the vehicle out of mud or newly fallen
snow, turn off the traction control system. The system
that controls engine performance interferes with the
process of freeing the front wheels. To turn off traction
control, press the TRAC OFF button. The traction
control system warning light will come on. The vehicle
stability control system (Stabilitrak
®) is always activated,
even when the traction control system is turned off.
To turn the traction control system back on, press the
TRAC OFF button again. The traction control system
warning light will go off. SeeTraction Control System
(TCS) Warning Light on page 3-34for more information.
Stabilitrak®System
The Stabilitrak®system helps provide integrated control
of the systems such as anti-lock brake system, traction
control and engine control. This system automatically
controls the brakes and engine to help prevent the
vehicle from skidding when cornering on a slippery road
surface or turning the steering wheel abruptly.
This system will activate when your vehicle speed
reaches or exceeds 9 mph (15 km/h), and will
deactivate when the vehicle speed reduces to below
9 mph (15 km/h).
You may hear a sound in the engine compartment for a
few seconds when the engine is started or just after the
vehicle begins to move. This means that the system is in
the self-check mode, but does not indicate a malfunction.
If the vehicle is going to skid during driving, the traction
control system warning light will blink and an alarm
will sound intermittently. Adjust your driving accordingly.
This light warns that there
is a problem somewhere
in the traction control
system or Stabilitrak
®.
4-10
Panic Brake Assist
Your vehicle has a panic brake assist system that
monitors the intention of the driver while braking. If the
system senses that the driver has applied hard/fast
pressure to the brake pedal, the system will generate
additional pressure, making it easier for the driver
to maintain brake application. When this happens the
brake pedal will feel easier to push. Just hold the brake
pedal down rmly and let the system work for you.
You may feel the brakes vibrate, or you may notice
some noise but this is normal. The brakes will return to
normal operation after the brake pedal has been
released.
The brake assist system becomes operational after the
vehicle has accelerated to a speed in excess of
approximately 6 mph (10 km/h). It stops operating when
the vehicle decelerates to a speed below approximately
3 mph (5 km/h).
All-Wheel Drive (AWD) System
If your vehicle has all-wheel drive (AWD), the AWD
system operates automatically without any action
required by the driver. If the front drive wheels begin to
slip, the rear wheels will automatically begin to drive
the vehicle as required. There may be a slight
engagement noise during hard use but this is normal.
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.
4-11
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.
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
are not 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 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
will 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. 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 mirrored surface — 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.
4-16
Hydroplaning
Hydroplaning is dangerous. So much water can build up
under your tires that they can actually ride on the
water. This can happen if the road is wet enough and
you are going fast enough. When your vehicle is
hydroplaning, it has little or no contact with the road.
Hydroplaning does not happen often. But it can if your
tires do not have much tread or if the pressure in
one or more is low. It can happen if a lot of water is
standing on the road. If you can see re ections
from trees, telephone poles, or other vehicles, and
raindrops dimple the water’s surface, there could be
hydroplaning.
Hydroplaning usually happens at higher speeds.
There just is not a hard and fast rule about hydroplaning.
The best advice is to slow down when it is raining.
Driving Through Deep Standing Water
Notice:If you drive too quickly through deep
puddles or standing water, water can come in
through your engine’s air intake and badly damage
your engine. Never drive through water that is
slightly lower than the underbody of your vehicle.
If you cannot avoid deep puddles or standing water,
drive through them very slowly.
Driving Through Flowing Water
{CAUTION:
Flowing or rushing water creates strong forces.
If you try to drive through owing water, as you
might at a low water crossing, your vehicle
can be carried away. As little as six inches of
owing water can carry away a smaller vehicle.
If this happens, you and other vehicle
occupants could drown. Do not ignore police
warning signs, and otherwise be very cautious
about trying to drive through owing water.
Some Other Rainy Weather Tips
Besides slowing down, allow some extra following
distance. And be especially careful when you
pass another vehicle. Allow yourself more clear
room ahead, and be prepared to have your
view restricted by road spray.
Have good tires with proper tread depth. SeeTires
on page 5-57.
4-20
When you want to leave the freeway, move to the
proper lane well in advance. If you miss your exit,
do not, under any circumstances, stop and back up.
Drive on to the next exit.
The exit ramp can be curved, sometimes quite sharply.
The exit speed is usually posted. Reduce your speed
according to your speedometer, not to your sense
of motion. After driving for any distance at higher
speeds, you may tend to think you are going slower
than you actually are.
Before Leaving on a Long Trip
Make sure you are ready. Try to be well rested. If you
must start when you are not fresh — such as after
a day’s work — do not plan to make too many miles
that rst part of the journey. Wear comfortable clothing
and shoes you can easily drive in.
Is your vehicle ready for a long trip? If you keep it
serviced and maintained, it is ready to go. If it needs
service, have it done before starting out. Of course,
you will nd experienced and able service experts in
GM dealerships all across North America. They will be
ready and willing to help if you need it.Here are some things you can check before a trip:
Windshield Washer Fluid:Is the reservoir full?
Are all windows clean inside and outside?
Wiper Blades:Are they in good shape?
Fuel, Engine Oil, Other Fluids:Have you checked
all levels?
Lamps:Are they all working? Are the lenses clean?
Tires:They are vitally important to a safe,
trouble-free trip. Is the tread good enough for
long-distance driving? Are the tires all in ated to
the recommended pressure?
Weather Forecasts:What is the weather outlook
along your route? Should you delay your trip a
short time to avoid a major storm system?
Maps:Do you have up-to-date maps?
4-23