1993 GMC SIERRA tires

Featwes & Contmk
The front axle portion of the indicator diagram will light up when you shift into
four-wheel drive.
A slight delay between shifting and the indicator’s lighting is
normal.
If the indicator does not light up, or if the front axle light does not go
out after you shift out of four-wheel drive, have your dealer check your
system.
When your headlights or parking lights are on, rotate the dial\

to the right of
your headlight switch up
to brighten, or down to dim, your transfer case
indicator light.
Transfer Case Shift Positions
2H (High): This setting is for driving in most street and highway situations.
Your front axle is not engaged in two-wheel drive.
4H (High): This setting engages your front axle to help drive your vehicle.
Use
4H when you need extra traction, such as on wet or icy roads, or in
most
off -road situations.
N (Neutral): Shift to this setting only when your vehicle needs to be towed or
when using a power take
off.
4L (Low): This setting also engages your front axle to give you extra traction,
but should be used only for off-road or on extremely slippery surfaces.
You can shift from
2H to 4H or from 4H to 2H while the vehicle is moving.
Your front axle will engage faster
if you take your foot off of the accelerator
for a few seconds after you shift. In extremely cold weather it may be
necessary to stop or slow the vehicle to shift out of
2H.
To shift into or out of 4L or N (Neutral):
1. Slow the vehicle to a roll, about 3 mph (5 kmlh) and shift your
2. Shift the transfer case shift lever in one continuous motion.
transmission into neutral.
Don’t pause in
N (Neutral) as you shift the transfer case into 4L, or your
aears could clash.
Kernember that driving
in 4H or 4L may reduce fuel economy. Also, driving in
four-wheel drive on dry pavement could cause your tires to wea\
r faster and
make your transfer case harder
to shift.
Front Axle Locking Feature
The front axle locks and unlocks automatically when you shift the transfer
case.
A slight delay for the axle to lock or unlock is normal. If the outside
temperature is very hot, or the vehicle has been used under hard driving
conditions, there may be a slight delay for the axle to unlock.
2-38
ProCarManuals.com

Your Driving and the Road
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.
AM409002
Sometimes, as when you’re driving on snow or ice, it’s e\
asy to ask more of
those control systems than the tires and road can provide. Tha\
t 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’s perception
time.
Then you have to bring up your foot and do it. That’s reaction time.
Average reaction time is about 314 of a second. But that’s only an average.
It might be less with one driver and as long as two or thre\
e seconds or
more with another. Age, physical condition, alertness, coordinati\
on, and
eyesight all play a part.
So do alcohol, drugs and frustration. But even in 3/4
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,
4-1 4
ProCarManuals.com

Rear Drum Brakes
If you have rear drum brakes, they don’t have the wear indicators, \
but if you
ever hear a rear brake rubbing noise, have the rear brake lining inspected.
Also, the rear brake drums should be removed and inspected each time\
the
tires are removed for rotation or changing. When you have the \
front brakes replaced, have the rear brakes inspected, too.
Brake linings should always be replaced as complete axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does not return to normal height, or if
there is a rapid increase in pedal travel. This could be a sign of brake
trouble.
Brake Adjusiment
Every time you make a brake stop, your disc brakes adjust for\
wear. If your
brake pedal goes down farther than normal, your rear drum brak\
es may need
adjustment. Adjust them by backing up and firmly applying the brakes a few
times.
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 wheels stopped rolling. That could be off the \
road, into the
very thing you were trying to avoid, or into traffic.
So, use a “squeeze” braking technique. This will give you max\
imum 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 Sieerhg
If you lose power steering assist because the engine stops or \
the system
fails to function, you can steer but it will take much more effort.
4-1 9
ProCarManuals.com

Your Driving and the Road
Steering Tips 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 me 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 sudd\
enly 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 de\
mand 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? Let 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.
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.
When you drive into a curve at night, it’s harder
to see the road ahead of
you because it bends away from the straight beams
of your lights. This is
one good reason to drive slower.
4-20
ProCarManuals.com

Your Driving and the Road
the right lane. (Remember that your right outside mirror is c\
onvex. 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.
Don’t overtake a slowly moving vehicle too rapidly. Even though the
Reconsider before passing the next vehicle.
brake lights 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 whe\
n the three
control systems (brakes, steering and acceleration) don’t ha\
ve 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 steel+-, arid 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 possib\
le.
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 ea\
sing your
foot
off the accelerator pedal. If your vehicle starts to slide (as when you turn
a corner on a wet, snow-
or ice-covered road), ease your foot off the
accelerator pedal as soon as you feel the vehicle start to sl\
ide. Quickly steer
the way you want the vehicle
to go. If you start steering quickly enough, your
vehicle
will straighten out. As it does, straighten the front wheels.
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 limit\
ed.
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 slid\
e. You
4-24
ProCarManuals.com

Your Driving and the Road
Loading Your Vehicle for Off-Road Driving
There are some important things to remember about how to load your
vehicle.
The heaviest things should be on the load floor and forward of your rear
Be sure the load is secured properly, so driving on the off-road terrain
axle. Put heavier items as far forward as you can.
doesn’t toss things around.
CAUTION
Cargo on the load floor piled higher than the seatbacks can be
3 thrown forward during a sudden stop. You or your passengers
could be injured. Keep cargo below the top
01 le seatbacks.
- Unsecured cargo on the load floor ca- >e tossecl about when
3-7 driving over rough terrain. You or your passengers can be strum
& by flying objects. Secure the cargo properly*
Heavy loads on the roof raise the vehicle’s center of gravi\
ty.
making it more likely
to roll over. You can be seriously injured
the vehicle rolls over. Put heavy loads inside the cargo area, not
on the roof. Keep in the cargo area as far forward and
low as Dossible.
I
You’ll find other important information in this manual. See “Vehicle Loading,’’
and “Tires” in the Index.
Traveling to Remote Areas
It makes sense to plan your trip, especially when going to a remote area.
Know the terrain and plan your route. You are much less likely to get bad
surprises. Get accurate maps of trails and terrain.
Try to learn of any blocked
or closed roads.
It’s also a good idea to travel with at least one other v\
ehicle. If something
happens to one of them, the other can help quickly.
Does your vehicle have a winch?
If so, be sure to read the winch
instructions. In a remote area,
a winch can be handy if you get stuck. But
you’ll want to know how to use
it properly.
Getting Familiar with Off-Road Driving
It’s a good idea to practice in an area that’s safe and close to home before
you
go into the wilderness. Off-road driving does require some new and\

different driving skills. Here’s what we mean.
4-26
ProCarManuals.com

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:
0
For
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
base (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 weight
on the downhill wheels. This could cause a downhill slide
or a rollover.
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.
reasons like these, you need to decide carefully whether to try to drive
across an incline. Just because the trail goes across the incl\
ine doesn’t mean
you have to drive it. The last vehicle to try
it might have rolled over.
CAUTIP!
4 Driving across an incline that’s too steep will make your v\
ehicle 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.
Q: What if I’m driving across an incline that’s not too steep, but I hit
some
loose gravel and start to slide downhill. What should I do?
A: If you feel your vehicle starting to slide sideways, turn downhill. This
should help straighten out the vehicle and prevent the side sl\
ipping. However,
a much better way to prevent this
is to get out and “walk the course” so you
know what the surface is like before you drive it.
4-33
ProCarManuals.com

Your Driving and the Road
Stalling on an Incline
If your vehicle stalls when you’re crossing an incline, be sure you (and your
passengers) get out on the uphill side, even
if the door there is harder to
open. If you get out on the downhill side and the vehicle starts to roll over,
you’ll be right in its path.
If you have to walk down the slope, stay out of the path the vehicle will take
if ‘it does roll over.
AM440002
I CAUTION
A Getting out on the downhill (low) side of a vehicle stopped across an
incline is dangerous. If the vehicle rolls over, you could be \
crushed
or killed. Always get out on the uphill (high) side
of the vehicle and
I stay well clear of the rollover path.
Driving In Mud, Sand, Snow, Or Ice
When you drive in mud, snow or sand, your wheels won’t get good traction.
You can’t accelerate as quickly, turning
is more difficult, and you’ll need
longer braking distances.
It’s best
to use a low gear when you’re in mud-the deeper the mud, the
lower the gear. In really deep mud, the. idea is to keep you\
r vehicle moving
so you don’t get stuck.
When you drive
on sand, you’ll sense a change in wheel traction. But it will
depend upon how loosely packed the sand is. On loosely packed \
sand (as
on beaches or sand dunes) your tires will tend to sink into the sand. This
4-34
ProCarManuals.com