brake GMC YUKON 2003 Workshop Manual

After Off-Road Driving
Remove any brush or debris that has collected on the
underbody, chassis or under the hood. These
accumulations can be are hazard.
After operation in mud or sand, have the brake linings
cleaned and checked. These substances can cause
glazing and uneven braking. Check the body structure,
steering, suspension, wheels, tires and exhaust
system for damage. Also, check the fuel lines and
cooling system for any leakage.
Your vehicle will require more frequent service due to
off-road use. Refer to the Maintenance Schedule
for additional information.
Driving at Night
Night driving is more dangerous than day driving.
One reason is that some drivers are likely to be
impaired—by alcohol or drugs, with night vision
problems, or by fatigue.
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Driving too fast through large water puddles or even
going through some car washes can cause problems,
too. The water may affect your brakes. Try to avoid
puddles. But if you can’t, try to slow down before you
hit them.
{CAUTION:
Wet brakes can cause accidents. They won’t
work as well in a quick stop and may cause
pulling to one side. You could lose control of
the vehicle.
After driving through a large puddle of water
or a car wash, apply your brake pedal lightly
until your brakes work normally.
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’re going fast enough. When your vehicle is
hydroplaning, it has little or no contact with the road.Hydroplaning doesn’t 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 reections 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 isn’t 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 can’t avoid deep puddles or standing water,
drive through them very slowly.
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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. SeeOff-Road
Driving with Your Four-Wheel-Drive Vehicle on
page 4-22for information about driving off-road.
Keep your vehicle in good shape. Check alluid
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. Shift to a lower gear when you go
down a steep or long hill.
{CAUTION:
If you don’t shift down, your brakes could get
so hot that they 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.
{CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. Your brakes will have
to do all the work of slowing down. They could
get so hot that they wouldn’t work well. You
would then have poor braking or even none
going down a hill. You could crash. Always
have your engine running and your vehicle in
gear when you go downhill.
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 you 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.
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If you have traction assist, keep the system on. It will
improve your ability to accelerate when driving on
a slippery road. But you can turn the traction system off
if your vehicle ever gets stuck in sand, mud, ice or
snow. SeeIf You Are Stuck: In Sand, Mud, Ice or Snow
on page 4-52. Even though your vehicle has a traction
system, you’ll want to slow down and adjust your driving
to the road conditions. SeeTraction Assist System
(TAS) on page 4-10.
If you don’t have a traction system, accelerate gently.
Try not to break the gentle 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 vehicle’s stability
when you make a hard stop on a slippery road.
Even though you have an anti-lock braking system,
you’ll want to begin stopping sooner than you would on
dry pavement. SeeBraking on page 4-6.Allow greater following distance on any
slippery road.
Watch for slippery spots. The road might bene
until you hit 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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Four-Wheel-Drive Vehicles
Use the following procedure to tow your vehicle:
1. Firmly set the parking brake.
2. Shift the transmission to PARK (P).3. Securely attach the vehicle being towed to the tow
vehicle.
4. Shift the transfer case to NEUTRAL. See
Four-Wheel Drive on page 2-26for the proper
procedure to select the NEUTRAL position for your
vehicle.
5. Release the parking brake only after the vehicle
being towed isrmly attached to the following
vehicle.
6. Turn the ignition off.
{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer
case into NEUTRAL can cause your vehicle to
roll even if the transmission is in Park (P). You
or others could be injured. Make sure the
parking brake isfirmly set before you shift the
transfer case to NEUTRAL.
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Dolly Towing
Two-Wheel-Drive Vehicles
Two-wheel-drive, vehicles, should not be towed with the
rear wheels on the ground. Two-wheel-drive
transmissions have no provisions for internal lubrication
while being towed. to properly tow these vehicles,
they should be placed on a platform trailer with all four
wheels off the ground.
Four-Wheel-Drive Vehicles
If your vehicle is equipped with Stabilitrak®it is not
designed to be dolly towed. If you need to tow your
vehicle, see“Dinghy Towing”earlier in this section.
Use the following procedure to tow your vehicle:
1. Firmly set the parking brake.
2. Shift the transmission to PARK (P).
3. Securely attach the vehicle being towed to the tow
vehicle.4. Shift the transfer case to NEUTRAL. See
Four-Wheel Drive on page 2-26for the proper
procedure to select the NEUTRAL position for your
vehicle.
5. Release the parking brake only after the vehicle
being towed isrmly attached to the following
vehicle.
6. Turn the ignition off.{CAUTION:
Shifting a four-wheel-drive vehicle’s transfer
case into NEUTRAL can cause your vehicle to
roll even if the transmission is in Park (P). You
or others could be injured. Make sure the
parking brake isfirmly set before you shift the
transfer case to NEUTRAL.
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You’ll get the best performance if you spread out the
weight of your load the right way, and if you choose the
correct hitch and trailer brakes.
For more information, seeTowing a Trailer on page 4-61
Towing a Trailer.
Towing a Trailer
{CAUTION:
If you don’t use the correct equipment and
drive properly, you can 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. Ask your
dealer for advice and information about towing
a trailer with your vehicle.Notice:Pulling a trailer improperly can damage
your vehicle and result in costly repairs not covered
by your warranty. To pull a trailer correctly, follow
the advice in this part, and see your dealer for
important information about towing a trailer with
your vehicle.
To identify the vehicle trailering capacity of your vehicle,
you should read the information in“Weight of the
Trailer”that appears later in this section.
If yours was built with trailering options, as many are,
it’s ready for heavier trailers. But trailering is different
than just driving your vehicle by itself. Trailering means
changes in handling, durability and fuel economy.
Successful, safe trailering takes correct equipment, and
it has to be used properly.
That’s the reason for this part. In it are many time-tested,
important trailering tips and safety rules. Many of
these are important for your safety and that of your
passengers. So please read this section carefully before
you pull a trailer.
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Trailer Brakes
If your trailer weighs more than 2,000 lbs. (900 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.
If your vehicle is equipped with Stabilitrak
®, your trailer
cannot tap into the vehicle’s hydraulic brake system.
Your trailer brake system can tap into the vehicle’s
hydraulic brake system only if:
The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.
The trailer’s brake system will use less than
0.02 cubic inches (0.3 cc) ofuid from your vehicle’s
master cylinder. Otherwise, both braking systems
won’t work well. You could even lose your brakes.
If everything checks out this far, make the brake tap at
the port on the master cylinder that sends theuid
to the rear brakes. But don’t use copper tubing for this.
If you do, it will bend andnally break off. Use steel
brake tubing.
Driving with a Trailer
{CAUTION:
If you have a rear-most window open and you
pull a trailer with your vehicle, carbon
monoxide (CO) could come into your vehicle.
You can’t see or smell CO. It can cause
unconsciousness or death. See“Engine
Exhaust”in the Index. To maximize your safety
when towing a trailer:
•Have your exhaust system inspected for
leaks, and make necessary repairs before
starting on your trip.
•Keep the rear-most windows closed.
•If exhaust does come into your vehicle
through a window in the rear or another
opening, drive with your front, main
heating or cooling system on and with the
fan on any speed. This will bring fresh,
outside air into your vehicle. Do not use
the climate control setting for maximum air
because it only recirculates the air inside
your vehicle. See“Climate Controls”in the
Index.
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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 as
responsive as your vehicle is by itself.
Before you start, check the trailer hitch and platform
(and attachments), safety chains, electrical connector,
lamps, 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 lamps and any trailer
brakes are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would 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 go 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 to the left, just move that 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.
If your vehicle is equipped with four-wheel steering and
if you use it while backing your trailer the same rules
apply. However, with four-wheel steering your rig
will respond more quickly and it may take additional
practice to get used to backing up with four-wheel
steering.
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Making Turns
Notice:Making very sharp turns while trailering
could cause the trailer to come in contact with the
vehicle. Your vehicle could be damaged. Avoid
making very sharp turns while trailering.
When you’re turning with a trailer, make wider turns
than normal. Do this so your trailer 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
The arrows on your instrument panel willash whenever
you signal a turn or lane change. Properly hooked up,
the trailer lamps will alsoash, telling other drivers
you’re about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel willash for turns even if the bulbs on the trailer
are burned out. Thus, you may think drivers behind
you are seeing your signal when they are not. It’s
important to check occasionally to be sure the trailer
bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gearbeforeyou start
down a long or steep downgrade. If you don’t shift
down, you might have to use your brakes so much that
they would get hot and no longer work well.
You can tow in DRIVE (D). You may want to shift the
transmission to THIRD (3) or, if necessary, a lower
gear selection if the transmission shifts too often
(e.g., under heavy loads and/or hilly conditions).
You may also want to activate the tow/haul mode if the
transmission shifts too often. See“Tow/Haul Mode”
for more information.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes. If you turn your
engine off immediately after towing at high altitude
on steep uphill grades, your vehicle may show signs
similar to engine overheating. To avoid this, let the
engine run while parked (preferably on level ground)
with the automatic transmission in PARK (P) for a
few minutes before turning the engine off. If you do get
the overheat warning, seeEngine Overheating on
page 5-29.
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