engine GMC YUKON DENALI 2003 Service Manual

Audio System(s)
Notice: Before you add any sound equipment to
your vehicle
- like a tape player, CB radio, mobile
telephone or two-way radio
- be sure you can
add what you want. If you can, it’s very important to
do
it properly. Added sound equipment may
interfere with the operation of your vehicle’s engine,
Delphi Electronics radio or other systems, and
even damage them. Your vehicle’s systems may interfere with the operation of sound equipment that
has been added improperly.
So, before adding sound equipment, check with
your dealer and be sure to check federal rules
covering mobile radio and telephone units.
Your audio system has been designed to operate easily
and to give years of listening pleasure. You will get
the most enjoyment out of
it if you acquaint yourself with
it first. Find out what your audio system can do and
how to operate all
of its controls to be sure you’re getting
the most out of the advanced engineering that went
into it. Your
vehicle may have a feature called Retained
Accessory Power (RAP). With RAP, you can play your
audio system even after the ignition is turned
off.
See “Retained Accessory Power (RAP)” under Ignition
Positions on page 2- 18.
Setting the Time
Press and hold the HR button until the correct hour
appears
on the display. Press and hold the MN button
until the correct minute appears on the display. The time
may be set with the ignition on or
off.
To synchronize the time with an FM station broadcasting
Radio Data System (RDS) information, press and
hold the hour and minute buttons at the same time until
RDS TIME appears
on the display. To accept this
time, press and hold the hour and minute buttons, at the
same time, for another
2 seconds. If the time is not
available from the station,
NO UPDAT will appear on the
display instead.
RDS time is broadcast once a minute. Once you have
tuned to an RDS broadcast station,
it may take a
few minutes for your time
to update.
3-58

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 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 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; 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’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.
4-6

Anti-lock Brake System
Your vehicle has anti-lock brakes. ABS is an advanced
electronic braking system that will help prevent a
braking skid.
When you start your engine and 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. This is normal.
If there’s a problem with
the anti-lock brake system, this warning light
will
stay on. See Anti-Lock
Brake System Warning
Light
on page 3-35.
Along with ABS, your vehicle has a Dynamic Rear
Proportioning (DRP) system.
If there’s a DRP problem,
both the brake and ABS warning lights will come
on
accompanied by a IO-second chime. The lights
and chime will come
on each time the ignition is turned
on until the problem is repaired. See your dealer for
service. Let’s say
the road is wet and you’re driving safely.
Suddenly, an animal jumps out in front of you. You slam
on the brakes and continue braking. Here’s 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.
4-7

Stabilitrak@ System
Your vehicle is equipped with Stabilitrak@, which
combines antilock brake, traction and stability control
systems and helps the driver maintain directional control
of the vehicle in most driving conditions.
When you first start your vehicle and begin
to drive
away, the system performs several diagnostic checks
to
insure there are no problems. You may hear or feel
the system working. This is normal and does not mean
there is a problem with your vehicle. The system
should initialize before the vehicle reaches
20 m.p.h.
(32 km/h). In some cases, it may take approximately two
miles
of driving before the system initializes.
If the system fails
to turn on or activate, the STABILITY
SYS DISABLED or SERVICE STABILITY message
will be displayed.
If the vehicle has gone through heavy
acceleration or braking or multiple turns during the
first two miles of driving after starting your vehicle, the
STABILITY
SYS DISABLED message may appear.
If this is the case, your vehicle does not need servicing.
You will need
to turn the vehicle off and then restart
it
to initialize Stabilitrak@.
If either message appears on the Driver Information
Center (DIC), and your vehicle hasn’t gone through hard
acceleration, braking
or multiple turns in the first two
miles of driving, your vehicle should be taken in
for service. The STABILITY SYS ACTIVE message will appear
on
the Driver Information Center (DIC) only when the
system is both on and activated. You may also feel or
hear the system working; this is normal. For more
information on
the stability messages, see Driver
Information Center (DIC) on page 3-43.
Stabilitrak@and part of the
traction control system can
be turned
off or back on
by pressing the
Stabilitrak@button located
on the instrument
When the system is turned
off, the traction off light will
illuminate, and the STABILITY SYS DISABLED
message will appear on the DIC to warn the driver that
both the stability system and part of the traction
control system are disabled. Your vehicle will still have
brake-traction control when Stabilitrak@is
off, but will
not be able
to use the engine speed management
system. See “Traction Control Operation” next for more
information.
4-9

When the Stabilitrak@system has been turned off you
may still hear system noises as a result of the
brake-traction control coming on.
It is recommended to leave the system on for normal
driving conditions, but it may be necessary
to turn
the system
off if your vehicle is stuck in sand, mud, ice
or snow, and you want
to “rock” your vehicle to
attempt to free it. It may also be necessary to turn off
the system when driving in extreme off-road conditions
where high wheel spin is required. See If
You Are
Stuck: In Sand, Mud, Ice or Snow on page
4-4 1.
Traction Control Operation
The traction control system is part of the
Stabilitrak@system. Traction control limits wheel spin by
reducing engine power
to the wheels (engine speed
management) and by applying brakes
to each individual
wheel (brake-traction control) as necessary.
The traction control system is enabled automatically
when you start your vehicle, and it will activate
and display the TRACTION ACTIVE message in the
Driver Information Center (DIC)
if it senses that any of
the wheels are spinning or beginning to lose traction
while driving. If you turn
off Stabilitrak@, only the
brake-traction control portion
of traction control will
work. The engine speed management will be disabled.
In this state, engine power is not reduced automatically
and the driven wheels can spin more freely. This
can cause the brake-traction control
to activate
constantly. For more information on the traction active
message, see Driver Information Center (DIC) on
page
3-43.
Notice: If the traction off light comes on due to
heavy braking and/or because the traction control
system has been continuously active, do not allow
the wheel@) of one axle to spin excessively.
If you
do, you may be causing damage to your transfer
case. This could lead to costly repairs not covered by
your warranty.
If the brake-traction control system activates constantly
or
if the brakes have heated up due to high speed
braking, the brake-traction control will be automatically
disabled. The system will come back on after the
brakes have cooled. This can take up
to two minutes ot
longer depending on brake usage.
Notice: Don’t allow the wheel(s) of one axle to spin
excessively when the traction
off, ABS and brake
lights are on and the
SERVICE STABILITY MESSAGE
is displayed. In this situation, damage to the transfer
case
is possible. This could lead to costly repairs not
covered by your warranty. You should immediately
reduce engine power until the lights and messages
are no longer displayed.
4-1 0

The traction control system may activate on dry or
rough roads or under conditions such as heavy
acceleration while turning or abrupt upshifts/downshifts
of the transmission. When this happens you may
notice a reduction in acceleration, or may hear
a noise
or vibration. This is normal.
If your vehicle is in cruise control when the system
activates, the STABILITY SYS ACTIVE message will
appear on the Driver Information Center and the cruise
control will automatically disengage. When road
conditions allow you
to use cruise again, you may
re-engage the cruise control. See “Cruise Control” under
Turn SignaVMultifunction
Lever on page 3-7
Stabilitrak@may also turn off automatically if it
determines that a problem exists with the system. If the
problem does not clear itself after restarting the
vehicle, you should see your dealer for service.
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 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 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 accelerate. Both control systems
- steering
and acceleration
- have to do their work where the tires
meet the road. Adding the sudden acceleration can
demand too much of those places. You can lose control.
What should you do
if this ever happens? Ease up on
the accelerator pedal, steer the vehicle the way
you want
it to go, and slow down.
4-1 1

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.
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 is 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: Any anti-lock brake system (ABS) helps
avoid only the braking skid.
4-1 5

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
vehicle.
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.
Tune your senses
to different kinds of signals. Your
eyes, for example, need
to constantly sweep the terrain
for unexpected obstacles. Your ears need to listen
for unusual tire or engine sounds. With your arms,
hands, feet and body, you’ll need to respond
to
vibrations and vehicle bounce. Controlling your vehicle is
the key
to successful off-road
driving. One of the best ways
to control your vehicle
is
to control your speed. Here are some things to keep
in mind.
At higher speeds:
you approach things faster and you have less time
to scan the terrain for obstacles.
you have less time to react.
you have more vehicle bounce when you drive over
obstacles.
you’ll need more distance for braking, especially
since u’re on an [-.7aved surface.
When ; u’re driving R-road, bouncing and
quick changes in direction can easily throw
you out
of position. This could cause you to
lose control and crash.
So, whether you’re
driving on or
off the road, you and your
passengers should wear safety belts.
4-1 8

If your engine is still running, shift the transmission
to REVERSE (R), release the parking brake, and
slowly back down the hill as straight as possible in
REVERSE (R).
As you are backing down the hill, put your left hand
on the steering wheel at the
12 o’clock position.
This way, you’ll be able
to tell if your wheels
are straight and maneuver as you back down.
It’s best that you back down the hill with your wheels
straight rather than in the left or right direction.
Turning the wheel
too far to the left or right
will increase the possibility of a rollover.
Here are some things you
must not do if you stall, or
are about to stall, when going up a hill.
Never attempt to prevent a stall by shifting into
NEUTRAL (N)
to “rev-up” the engine and regain
forward momentum. This won’t work. Your vehicle
will roll backwards very quickly and you could
go out of control. Instead, apply the
regular brake to stop the vehicle.
Then apply the parking brake. Shift to
REVERSE
(R), release the parking brake, and
slowly back straight down.
Never attempt to turn around if you are about to
stall when going up a hill. If the hill is steep
enough to stall your vehicle, it’s steep enough
to
cause you to roll over if you turn around. If you can’t
make it up the hill, you must back straight down
the hill.
Q: Suppose, after stalling, I try to back down
the hill and decide
I just can’t do it. What
should
I do?
A: Set the parking brake, put your transmission in
PARK
(P) and turn off the engine. Leave the
vehicle and
go get some help. Exit on the uphill
side and stay clear of the path the vehicle would
take
if it rolled downhill.
4-22

Driving Downhill
When off-roading takes you downhill, you’ll want to
consider a number of things:
How steep is the downhill? Will I be able to maintain
vehicle control?
0 What’s the surface like? Smooth? Rough? Slippery?
Hard-packed dirt? Gravel?
Are there hidden surface obstacles? Ruts? Logs?
Boulders?
What’s at the bottom of the hill? Is there a hidden
creek bank or even a river bottom with large rocks?
If you decide you can go down a hill safely, then try to
keep your vehicle headed straight down, and use a
low gear. This way, engine drag can help your brakes
and they won’t have to do all the work. Descend slowly,
keeping your vehicle under control at all times.
Heavy braking when going down a hill can
cause your brakes to overheat and fade.
This could cause
loss of control and a serious
accident. Apply the brakes lightly when
descending a hill and use a
low gear to keep
vehicle speed under control.
0: Are there some things I should not do when
driving down a hill?
A: Yes! These are important because if you ignore
them you could lose control and have a serious
accident.
When driving downhill, avoid turns that take you
across the incline of the hill. A hill that’s not too
steep to drive down may be too steep to drive across. You could roll over
if you don’t drive
straight down.
Never go downhill with the transmission in
NEUTRAL (N). This is called “free-wheeling.”
Your brakes will have to
do all the work and could
overheat and fade.
4-23