1994 GMC SIERRA Owners Manual

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’re driving on snow or ice, it‘s 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 perceptiorz time and renction time.
First, you have to decide to push on the brake pedal. That’spemptiorz time.
Then you have to bring up your foot and do it. That’s reaction time.
Average reaction time is about 3/4 of a second. But that’s only an average. It
might be less
with one driver and as long as two 01- 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 34 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’s pavement
or gravel); the condition of the road (wet, dry,
icy); tire tread; and the condition of your brakes.
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.
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If your engine ever stops while you’re driving, brake normally but don’t
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.
Anti-Lock Brakes (ABS)
Your vehicle has an advanced electronic braking system that can help you
keep it under control.
When you start your vehicle and begin to drive away, you may hear
a
momentary motor or clicking noise. The ABS motor comes on momentarily
when
the vehicle reaches 8 mph (I 2 km/h). And you may even notice that
your brake pedal moves a little while this is going on. This
is the ABS
system testing itself.
Here’s how anti-lock works. Let’s say the road is wet. You’re driving safely.
Suddenly an animal jumps out
in front of you.
You slam on the brakes. Here’s what happens with ABS.
A computer senses that the rear wheels are slowing down.
IT one of the rear
wheels is about to stop rolling, the computer will work
the brakes at the rear
wheels.
It is programmed to make the most of available tire and road
conditions.
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As you brake, your computer keeps receiving updates on rear 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. 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.
To Use Anti-Lock
Use rear-wheel anti-lock like regular brakes. You may feel the brakes
vibrate, or
you may notice some noise outside your vehicle, but this is
normal. Let anti-lock work for
you, but remember: Your front wheels can
still stop rolling.
If that happens, release enough pressure on the brakes to
get the wheels rolling again
so that you can steer.
With the four-wheel drive option, you won't have anti-lock braking when
you shift into four-wheel drive. But you will have regular braking. When
you shift back into two-wheel drive, you
will have anti-lock again.
Braking in Emergencies
At some time, nearly every driver gets into a situation that requires hard
braking.
You have the rear-wheel anti-lock braking system.
Your front wheels can
stop rolling
when you brake very hard. Once they do, the vehicle can't
respond
to your steering. Momentum will carry it in whatever direction it
was headed when the front wheels stopped rolling. That could be off the
road, into the very thing you were trying to avoid, or into traffic.
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So, use a “squeeze” 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. When you do,
it will help
maintain steering control. 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.
Steering lips
Driving on Curves
It’s important to take curves at a reasonable speed.
A lot of the “driver lost control” 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. Adding the hard braking can demand
too much at 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.
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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.
Try
to adjust your speed so you can “drive” 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.
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.
Your Vehicle can perform very well
in emergen.cies like these. First apply
your brakes, but not enough to lock your front wheels. 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 quicltly, and just
as quickly
straighten
the wheel once you have avoided the object.
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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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Off-Road Recovery
You may find sometime that your right wheels have dropped off the edge of
a road onto the shoulder while you’re driving.
If the level of the shoulder is only slightly below
the pavement, recovery
should be fairly easy. Ease
off the accelerator and then, if there is nothing in
the way, steer so that your vehicle straddles the edge of the pavement. You
can turn the steering wheel up to 1/4 turn until the right front tire contacts
the pavement edge. Then turn your steering wheel
to go straight down the
roadway.
1. Edge of Road
Surface
2. Slow Down
3. Left Approx.
Quarter Turn
4. Recover
Passing
The driver of a vehicle about to pass another on a two-lane highway waits
for just the right moment, accelerates, moves around the vehicle ahead, then
goes back into
the right lane again. A simple maneuver?
Not necessarily! Passing another vehicle
on a two-lane highway is a
potentially dangerous move, since the passing vehicle occupies the same
lane
as oncoming traffic for several seconds. A miscalculation, an error in
judgment, or
a brief surrender to frustration or anger can suddenly put the
passing driver face to face
with the worst of all traffic accidents - the
head-on collision.
So here are some tips for passing:
0 “Drive ahead.” Look down the road, to the sides. and to crossroads for
situations that might affect your passing patterns.
If you have any doubt
whatsoever about making
a successful pass, wait for a better time.
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Watch for traffic signs, pavement markings, and lines. If you can see a
sign
up ahead that might indicate a turn or an intersection, delay your
pass.
A broken center line usually indicates it’s all right to pass
(providing the road ahead is clear). Never cross
a solid line on your
side of the lane or
a double solid line, even if the road seems empty of
approaching traffic.
Do not get too close to the vehicle you want to pass while you’re
awaiting an opportunity. For one thing, following
too closely reduces
your area of
vision, especially if you’re following a larger vehicle.
Also, you won’t 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 don’t 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 cars are lined up to pass a slow vehicle, wait your turn. But
take care that someone isn’t 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 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 lights are not flashing,
it may be slowing down or start
If you’re being passed, make it easy for the following driver
ahead
of you. Perhaps you can ease a little to the right. ;ing to turn.
to get
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.
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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 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’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). 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.
Remember: The rear-wheel anti-lock braking system (RWAL) helps avoid
only
a rear braking skid. In a braking skid (where the front wheels are no
longer rolling), release enough pressure
on the brakes to get the front wheels
rolling again. This restores steering control. Push the brake pedal down
steadily when you have
to stop suddenly. As long as the front wheels are
rolling, you
will have steering control.
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