brake GMC SIERRA 1993 Service Manual

Your Driving and the Road
driving. Too-fast or too-slow driving breaks a smooth traffic flow. Treat the left
lane on a freeway as a passing lane.
Entering the Freeway
At the entrance there is usually a ramp that leads to the freewa\
y. If you have
a clear view of the freeway as you drive along the entrance ramp, you
should begin to check traffic.
Try to determine where you expect to blend
with the flow.
If traffic is light, you may have no problem. But if it is heavy,
find a gap as you move along the entering lane and time your approach. T\
ry
to merge into the gap at close to the prevailing speed. Switc\
h on your turn signal, check your rearview mirrors as you move along, and gla\
nce over your
shoulder as often as necessary.
Try to blend smoothly with the traffic flow.
Driving on the Freeway
Once you are on the freeway, adjust your speed to the posted \
limit or to the
prevailing rate if it’s slower. Stay in the right lane unle\
ss you want to pass.
If
you are on a two-lane freeway, treat the right lane as the slow lane and the
left lane as the passing lane. If you are on a three-lane fr\
eeway, treat the
right lane as the slower-speed through lane, the middle lane a\
s the
higher-speed through lane, and the left lane as the passing la\
ne.
Before changing lanes, check your rearview mirrors. Then use yo\
ur turn
signal. Just before you leave the lane, glance quickly over
your shoulder to
make sure there isn’t another vehicle in your “blind” \
spot.
If you are moving from an outside to a center lane on a freeway having
more than two lanes, make sure another vehicle isn’t about \
to move into the
same spot. Look at the vehicles
two lanes over and watch for telltale signs:
turn signals flashing, an increase in speed, or moving toward \
the edge of the lane. Be prepared to delay your move.
Once you are moving on the freeway, make certain you allow a \
reasonable
following distance. Expect to move slightly slower at night.
Leaving the Freeway
When you want to leave the freeway, move to the proper lane \
well in
advance. Dashing across lanes at the last minute is dangerous. \
If you miss
your exit do not, under any circumstances, stop and back up. \
Drive on to the next exit.
At each exit point is a deceleration lane. Ideally it should be long enough for
you to enter
it at freeway speed (after signaling, of course) and then do yo\
ur
braking before moving onto the exit ramp. Unfortunately, not all deceleration
lanes are long enough-some are too short for all the braking. \
Decide when
to start braking.
If you must brake on the through lane, and if there is traffic
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close behind you, you can allow a little extra time and flash\
your brake lights (in addition to your turn signal) as extra warning that you are about to slow
down and exit.
The exit ramp can be curvea, somerlmes 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.\
For example,
40 rnph (65 km/h) might seem like only 20 mph (30 km/h). Obviously, this
could lead to serious trouble
on a ramp designed for 20 mph (30 kmlh)!
Driving a Long Distance
Although most long trips today are made on freeways, there are\
still many
made on regular highways.
Long-distance driving on freeways and regular highways is the s\
ame in some
ways. The trip has to be planned and the vehicle prepared, you drive at\

higher-than-city speeds, and there are longer turns behind the \
wheel. You’ll
enjoy your trip more
if you and your vehicle are in good shape. Here are
some tips for a successful long trip.
Before Leaving on a Long Trip
Make sure you’re ready. Try to be well rested. If you must start when you’re
not fresh-such as after a day’s work-don’t plan to make too many miles
that first 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’s ready to go.
If it needs service, have it done before starting out. Of
course, you’ll find experienced and able service experts in \
your vehicle’s
dealerships all across North America. They’ll 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
Wiper Blades: Are they in good shape?
Fuel, Engine Oil, Other Fluids: Have you checked all levels?
Lights: 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 inflated to the
recommended pressure? inside and outside?
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As in any driving situation, keep pace with traffic and allow adequat\
e
following distances.
Hill and Mountain Roads
I r
AM470001
Driving on steep hills or mountains is different from driving in flat or rolling
terrain.
If you drive regularly in steep country, or if you’re planning to visit
there, here are some tips that can make your trips safer and \
more enjoyable.
(See “Off-Road” in the Index for information about driving off-road.)
Keep your 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. Don’t make your brakes do it
all. Shift to a lower gear when you go down a steep or long hill. That
way, you will slow down without excessive use of your brakes.
If you don’t shift down,’ your brakes could get so hot that they
- b 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. I I
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I CAUTION
A Coasting downhill in N (Neutral) or with the ignition off is dangerous.
E ‘ Your brakes will have to do all the work of slowing down. They could
get
so hot that they wouldn’t work well. You could crash. Always
have your engine running and your vehicle in gear when you go
downhill.
l I
e
e
e
e
e
Know how to go uphill. You may want to shift down to a lower gear.
The lower gears help cool your engine and transmission, and yo\
u 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. That way, you won’t be
surprised by a vehicle coming toward you in the same lane.
It takes longer to pass another vehicle when you’re going uphill. You’ll
want
to leave extra room to pass. If a vehicle is passing you and
doesn’t have enough room,
slow down to make it easier for the other
vehicle to get by.
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 fallin\
g rocks
area, or winding roads. Be alert to these and take appropriate action.
Winter driving can present special problems. See “Winter Driv\
ing” in the
Index.
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Parking on Hills
AM470025
Hills and mountains mean spectacular scenery. But please be car\
eful where
you stop
if you decide to look at the view or take pictures. Look for pull-offs
or parking areas provided for scenic viewing.
Another part
of this manual tells how to use your parking brake (see “Parking
Brake” in the Index). But on a mountain or steep hill, you can
do one more
thing. You can turn your front wheels to keep your vehicle from rolling
downhill or out into traffic.
Here’s how:
Downhill Parking
-_ .
AM470031
Turn your wheels to the right.
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AM470053
If there is no curb when you’re parking uphill, turn the wheels to the right.
If there is no curb when you’re parking uphill on the left side of a one-way
street, your wheels should be turned to the left.
Torque Lock (Automatic Transmission)
If you are parking on a hill and you don’t shift your tra\
nsmission into P
(Park) properly, the weight of the vehicle may put too much force on the
parking pawl in the transmission. You may find it difficult to pull the shift lever
out of
P (Park). This is called “torque lock.” To prevent torque lock, always
be sure to shift into
P (Park) before you leave the driver’s seat. To find out
how, see “Shifting Into
P (Park)” in the Index.
When you are ready to drive, move the shift lever out
of P (Park) BEFORE
you release the parking brake.
If “torque lock” does occur, you may need to have another vehicle push
yours a little uphill to take some of the pressure from the transmission,
so
you can pull the shift lever out of P (Park).
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AM48001 7
What’s the worst time for this? “Wet ice.’’ 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.
Your anti-lock brakes improve your ability
to make a hard stop on a slippery
road. Even though you have the anti-lock braking system, you’\
ll want to begin
stopping sooner than you would on dry pavement. See “Anti-lo\
ck‘’ in the Index.
Allow greater following distance on any slippery road.
Watch for slippery spots. The road might be fine until you hi\
t a spot
that’s covered with ice. On an otherwise clear road, ice patches may
appear in shaded areas where the sun can’t reach: around clumps of
trees, behind buildings,
or under bridges. Sometimes the surface of a
curve
or an overpass may remain icy when the surrounding roads are
clear.
If you see a patch of ice ahead of you, brake before you are on
it. Try not to brake while you’re actually on the ice, and\
avoid sudden
steering maneuvers.
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AM480043
Run your engine only as long as you musk. This saves fuel. When you run
the engine, make it go a little faster than just idle. That is, push the
accelerator slightly. This uses less fuel for the heat that yo\
u get and
it keeps
the battery (or batteries) charged. You will need a well-charged battery (or
batteries) to restart the' vehicle, and possibly for signaling later on with your
headlights. Let the heater run for awhile.
If you 'have a diesel engine, you
may have to run it at a higher speed
to lget enough heat. Then, shut the
engine
off and close the window almost all the way to preserve the heat.
Start the engine again and repeat this only when you feel really
uncomfortable from the cold. But
do it as little as'possible. Preserve the fuel
as long as you can.
To help keep warm, you can get out of the vehicle and
do some fairly vigorous exercises every half hour or so until help comes.
If You're Stuck in Deep Snow
This manual explains how to get the vehicle out of deep snow without
damaging it. See "Rocking Your Vehicle" in the Index.
Towing a mailer
CAUTION I
If you don't use the correct equipment and drive properly, you ca\
n
lose control when you pull a trailer. For example, if the trailer is too
heavy, the brakes may not work well-or even at all. You and your
passengers could be seriously injured. Pull a trailer only if \
you have
followed all the steps in this section.
I
i'- ." "
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Your Driving and the Road
Total Weight on Your Vehicle’s Tires
Be sure your vehicle’s tires are inflated to the limit for cold tires. You’ll find
these numbers on the Certification label at the rear edge of the driver’s door
(or see “Tire Loading” in the Index). Then be sure you don’t go over the
GVW limit for your vehicle.
Hitches
It’s important to have the correct hitch equipment. Crosswinds, large trucks
going by, and rough roads are a few reasons why you’ll need the righ\
t hitch.
Here are some rules
to follow:
If your vehicle has a step bumper and you are going to use a ball-type
hitch, remove the pad and cut holes in
it to match the hitch and safety
chain holes in the bumper.
If you’ll be pulling a trailer that, when loaded, will weigh more than 4,000
pounds (1800 kg) be sure to use a properly mounted weight-distributing
hitch and sway control of the proper size. This equipment is very
important for proper vehicle loading and good handling when you\
’re
driving.
Safety Chains
You should always attach chains between your vehicle and your trail\
er. Cross
the safety chains under the tongue of the trailer
so that the tongue will not
drop
to the road if it becomes separated from the hitch. Instructions about
safety chains may be provided by the hitch manufacturer
or by the trailer
manufacturer. Follow the manufacturer’s recommendation for atta\
ching safety
chains. Always leave just enough slack
so you can turn with your rig. And,
never allow safety chains to drag .on the ground.
Trailer Brakes
If your trailer weighs more than 1,000 pounds (450 kg) loaded, then it needs
its own brakes-and they must be adequate. Be sure
to read and follow the
instructions for the trailer brakes
so you’ll be able to install, adjust and
maintain them properly.
Don’t tap into your vehicle’s brake system
if the trailer’s brake system will use
more than
0.02 cubic inch (0.3~~) of fluid from your vehicles master cylinder.
If it does, both braking systems won’t work well. You could even lose your
brakes.
Will the trailer brake parts take 3,000 psi (20 650 kPa) of pressure? If
not, the trailer brake system must not be used with your vehi\
cle.
If everything checks out this far, then make the brake fluid tap at the
port on the master cylinder that sends fluid
to the rear brakes. But don’t
use copper tubing for this.
If you do, it will bend and finally break off.
Use steel brake tubing.
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Driving with a Trailer
Towing a trailer requires a certain amount of experience. Before setting out
for the open road, you’ll want to get to know your rig. Acquaint yourself with
the feel of handling and braking with the added weight of the trailer. And
always keep in mind that the vehicle you are driving is now a good deal
longer and not nearly
so responsive as your vehicle is by itself.
Before you start, check the trailer hitch and platform, safety \
chains, electrical
connector, lights, tires and mirror adjustment.
If the trailer has electric brakes,
start your vehicle and trailer moving and then apply the trailer brake controller
by hand to be sure the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to be sure that the load is secure, and
that the lights and any trailer brakes are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as you w\
ould when
driving your vehicle without a trailer. This can help you avoid situations \
that
require heavy braking and sudden turns.
Passing
You’ll need more passing distance up ahead when you’re towing a trailer.
And, because you’re a good deal longer, you’ll need to g\
o much farther beyond the passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand. Then, to move the
trailer left, just move your hand to the left.
To move the trailer to the right,
move your hand to the right. Always back up slowly and,
if possible, have
someone guide you.
Making Turns
When you’re turning with a trailer, make wider turns than normal. Do this so
your trailer wheels won’t strike soft shoulders, curbs, road signs\
, trees, or
other objects. Avoid jerky or sudden maneuvers. Signal well in advance.
Turn Signals When Towing a Trailer
When you tow a trailer, your vehicle has to have a different turn signal
flasher and extra wiring. The green arrows on your instrument \
panel will flash
whenever you signal a turn or lane change. Properly hooked up, the trailer
lights will also flash, telling other drivers you’re about t\
o turn, change lanes,
or stop.
When towing a trailer, the green arrows on your instrument pan\
el will flash for
turns even
if the bulbs on the trailer are burned out. Thus, you may think
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