2004 GMC YUKON DENALI brake light

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 is a problem with
the anti-lock brake system,
this warning light will
stay on. See
Anti-Lock
Brake System Warning
Light on page 3-37
.
Along with ABS, your vehicle has a Dynamic Rear
Proportioning (DRP) system. If there is a DRP problem,
both the brake and ABS warning lights will come on
accompanied by a 10-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 us say the road is wet and you are driving safely.
Suddenly, an animal jumps out in front of you. You slam
on the brakes and continue braking. Here is 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

StabilitrakžSystem
Your vehicle is equipped with Stabilitrakž, 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 ®rst 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 mph
(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
®rst 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
ž. 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 ®rst 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 3-46.
Stabilitrak
žand part of the
traction control system can
be turned off or back on
by pressing the
Stabilitrak
žbutton located
on the instrument panel.
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
žis off, but
will not be able to use the engine speed management
system. See ªTraction Control Operationº next for
more information.
4-9

When the Stabilitrakžsystem 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 ªrockº 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 4-41.
Traction Control Operation
The traction control system is part of the
Stabilitrakžsystem. 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
ž, 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 activateconstantly. For more information on the traction active
message, see
Driver Information Center (DIC) on
page 3-46.
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(s) of one axle to spin excessively. If
you do, you may be causing damage to the
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 disabled and
the TRACTION SYS LIMITED message will be
displayed. In the limited mode, the traction control
system will only use engine traction-control and is limited
in its ability to provide optimal performance since the
system will not utilize brake traction-control to control
slip on the drive wheels. The system will return to normal
after the brakes have cooled. This can take up to two
minutes or longer depending on brake usage.
Notice:If you allow the wheel(s) of one axle to spin
excessively while the traction off, ABS and brake
warning lights and the SERVICE STABILITY
MESSAGE are displayed, you could damage the
transfer case. The repairs would not be covered by
your warranty. Reduce engine power and do not
spin the wheel(s) excessively while these lights and
this message are displayed.
4-10

Driving Downhill
When off-roading takes you downhill, you will want to
consider a number of things:
·How steep is the downhill? Will I be able to maintain
vehicle control?
·What is the surface like? Smooth? Rough?
Slippery? Hard-packed dirt? Gravel?
·Are there hidden surface obstacles? Ruts? Logs?
Boulders?
·What is 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 will not have to do all the work. Descend
slowly, keeping your vehicle under control at all times.
{CAUTION:
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.
Q: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 is not too
steep to drive down may be too steep to drive
across. You could roll over if you do not drive
straight down.
·Never go downhill with the transmission in
NEUTRAL (N). This is called ªfree-wheeling.º
Your brakes will have to do all the work and could
overheat and fade.
4-23

The heavier the rain, the harder it is to see. Even if your
windshield wiper blades are in good shape, a heavy
rain can make it harder to see road signs and
traffic signals, pavement markings, the edge of the road
and even people walking.
It is wise to keep your wiping equipment in good shape
and keep your windshield washer tank ®lled with
washer ¯uid. Replace your windshield wiper inserts
when they show signs of streaking or missing areas on
the windshield, or when strips of rubber start to
separate from the inserts.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 not, try to slow down before you
hit them.
{CAUTION:
Wet brakes can cause accidents. They will not
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.
4-30

Trailer Wiring Harness
Heavy-Duty Trailer Wiring Package
Your vehicle is equipped with the seven-wire trailer
towing harness. This harness with a seven-pin universal
heavy-duty trailer connector is attached to a bracket
on the hitch platform.The Center High-Mounted Stoplamp (CHMSL) wire is
tied next to the trailer wiring harness for use with a
trailer.
The seven-wire harness contains the following trailer
circuits:
·Yellow: Left Stop/Turn Signal
·Dark Green: Right Stop/Turn Signal
·Brown: Taillamps
·White: Ground
·Light Green: Back-up Lamps
·Red: Battery Feed
·Dark Blue: Trailer Brake
4-62

Notice:
·Using the wrong ¯uid can badly damage brake
system parts. For example, just a few drops of
mineral-based oil, such as engine oil, in your
brake system can damage brake system
parts so badly that they will have to be replaced.
Do not let someone put in the wrong kind of
¯uid.
·If you spill brake ¯uid on your vehicle's painted
surfaces, the paint ®nish can be damaged. Be
careful not to spill brake ¯uid on your vehicle. If
you do, wash it off immediately. See
Appearance
Care on page 5-92.
Brake Wear
Your vehicle has four-wheel disc brakes.
Disc brake pads have built-in wear indicators that make
a high-pitched warning sound when the brake pads
are worn and new pads are needed. The sound
may come and go or be heard all the time your vehicle
is moving (except when you are pushing on the
brake pedal ®rmly).
{CAUTION:
The brake wear warning sound means that
soon your brakes will not work well. That
could lead to an accident. When you hear the
brake wear warning sound, have your vehicle
serviced.
Notice:Continuing to drive with worn-out brake
pads could result in costly brake repair.
Some driving conditions or climates may cause a brake
squeal when the brakes are ®rst applied or lightly
applied. This does not mean something is wrong with
your brakes.
Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly tighten wheel nuts in
the proper sequence to GM torque speci®cations.
Brake linings should always be replaced as complete
axle sets.
5-38

TPM Sensor Identi®cation Codes
Each TPM sensor has a unique identi®cation code.
Any time you rotate your vehicle's tires or replace one
or more of the TPM sensors, the identi®cation codes will
need to be matched to the new tire/wheel position.
Each tire/wheel position is matched to a sensor,
by increasing or decreasing the tire's air pressure.
The sensors are matched to the tire/wheel positions in
the following order: left front (LF); right front (RF);
right rear (RR) and left rear (LR).
You will have one minute to match the ®rst tire/wheel
position, and ®ve minutes overall to match all four
tire/wheel positions. If it takes longer than one minute,
to match the ®rst tire and wheel, or more than ®ve
minutes to match all four tire and wheel positions the
matching process stops and you will need to start over.
The TPM sensor matching process is outlined below:
1. Set the Parking brake.
2. Turn the ignition switch to RUN with the engine off.
3. Turn the exterior lamp switch from ªOffº to ªOnº
four times within 3 seconds. A double horn chirp
will sound and the TPM low tire warning light
will begin to ¯ash. The double horn chirp and¯ashing TPM warning light indicate that the TPM
matching process has started. The TPM warning
light should continue ¯ashing throughout the
matching procedure. The SERVICE TIRE
MONITOR message will be displayed on the Driver
Information Center (DIC).
4. Start with the left (driver's side) front tire.
5. Remove the valve cap from the valve cap stem.
Activate the TPM sensor by increasing or
decreasing the tire's air pressure for 10 seconds,
then stop and listen for a single horn chirp.
The single horn chirp should sound within 15
seconds, con®rming that the sensor identi®cation
code has been matched to this tire and wheel
position. If you do not hear the con®rming single
horn chirp, you will need to start over with step
number one. To let air-pressure out of a tire you can
use the pointy end of the valve cap, a pencil-style
air pressure gage or a key.
6. Proceed to the right (passenger's side) front tire,
and repeat the procedure in step 5.
7. Proceed to the right (passenger's side) rear tire,
and repeat the procedure in step 5.
8. Proceed to the left (driver's side) rear tire, and
repeat the procedure in step 5.
5-65