2003 GMC SIERRA DENALI brake light

REDUCED BRAKE POWER
If your vehicle has vacuum assist power brakes, this
message will be displayed and you may notice that the
brake pedal is harder to push and it will take longer
to stop. You may also hear a motor running and feel a
slight vibration in the brake pedal or steering wheel
when you apply or release the brake pedal even
if your
foot is not on the brake pedal. This indicates that the
Supplemental Brake Assist system is working to
maintain braking power.
If you are braking lightly, you
may not notice any difference in the operation
of
your brakes.
This message may also be displayed for brief periods
if
you are driving at higher elevations and are pumping
your brakes or braking hard. The message may
clear after you’ve lifted your foot from the accelerator
pedal an allowed the vehicle to coast
in gear or after you
have driven down to a lower elevation. This is a
normal operation of your brake system and does not
require that the brake system be serviced. However,
if
the message does not clear, your brake system
needs service. While the message is displayed you will
notice that the brake pedal is harder to push and
it
will take longer to stop. See Brake System Warning
Light
on page 3-34.
Your brake system may not be working
properly if the REDUCED BRAKE POWER
message is displayed. If this message comes
on and stays on while driving, pull
off the road
and stop carefully. The brake pedal will be
harder to push and
it will take longer to stop.
If the message is no longer displayed after you
have pulled
off the road and stopped, you can
continue driving.
However, if the message is still displayed, or if
it comes on again when you are driving, there
is a problem with your brake system. If you
continue to drive with this message displayed
it can lead to an accident. You should have the
vehicle towed for service. Also, see Brake
System Warning Light in the Index.
3-57

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 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’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

Q: Suppose, after stalling, I try to back down the hill
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.
and decide
I just can’t
do it. What should I do?
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?
What’s the surface like? Smooth? Rough? Slippery?
Hard-packed dirt? Gravel?
0 Are there hidden surface obstacles? Ruts? Logs?
What’s at the bottom of the hill? Is there a hidden
Boulders?
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 hate to do all the work. Descend slowly,
keeping your vehicle under control at all times. Heavy
braking when going down a
h 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
A: Yes! These are important because if you ignore
driving
down a hill?
0
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.
4-24

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's wise to keep your wiping equipment in good shape
and keep your windshield washer tank filled with
washer fluid. 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't, try to slow down before you
hit them.
Wet brakes
4 1 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.
4-3 1

Trailer Wiring Harness
Your pickup is equipped with the eight-wire trailer
towing harness. This harness with a seven-pin universa
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, slide-in camper or cap. The
eight-wire harness contains the following trailer
circuits:
Yellow: Left Stopnurn Signal
Dark Green: Right Stopnurn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Light Blue: Center High-Mounted Stoplamp
(CHMSL)
Red: Battery Feed
Dark Blue: Trailer Brake
If your trailer
is equipped with electrical brakes, you can
get a jumper harnesdelectric trailer brake control
with a trailer battery feed fuse from your dealer. This
harness and fuse should be installed by your dealer or a
qualified service center.
If you need to tow a light-duty trailer with a standard
four-way round pin connector, you can also get an
adapter from your dealer.
4-60

Notice:
Using the wrong fluid 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’ll have to be replaced.
Don’t let someone
put in the wrong kind of fluid.
If you spill brake fluid on your vehicle’s painted
surfaces, the paint finish can be damaged.
Be careful not to spill brake fluid on your
vehicle.
If you do, wash it off immediately.
See “Appearance Care” in the Index.
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 firmly). The
brake wear warning sound means that soon
your brakes won’t work well. That could lead to
an accident. When you hear the brake wear
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 first 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 specifications.
Brake linings should always be replaced as complete
axle sets.
See
Brake System Inspection on page 6- 15
5-41

Notice: If the other system isn’t a 12-volt system
with a negative ground, both vehicles can be
damaged.
2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren’t touching
each other. If they are, it could cause a ground
connection you don’t want. You wouldn’t be able to
start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake firmly on both vehicles involved
in the jump start procedure. Put the automatic
transmission in PARK
(P) before setting the parking
brake.
If you have a four-wheel-drive vehicle, be
sure the transfer case is in a drive gear not in
NEUTRAL.
Notice: If you leave your radio on, it could be badly
damaged. The repairs wouldn’t be covered by
your warranty.
3.
4.
Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or in the accessory power outlets. Turn
off
the radio and all the lamps that aren’t needed.
This will avoid sparks and help save both batteries.
And it could save your radio!
Open the hoods and locate the positive
(+) and
negative
(-) terminal locations of the other vehicle.
Your vehicle has a remote positive
(+) jump starting
terminal and a remote negative
(-) jump starting
terminal. You should always use these remote
terminals instead of the terminals on the battery.
The remote positive
(+) terminal is located behind
a red plastic cover near the engine accessory
drive bracket.
To uncover the remote positive (+)
terminal, open the red plastic cover.
The remote negative
(-) terminal is located on the
engine drive bracket on all
V8 and diesel
engines, and on the thermostat housing on the
8.1L engine. On
V8 engines it is marked ”GND.”
See
Engine Compartment Overview on page 5-12
for more information on location.
5-44

Accessory Power Outlets ................................. 3-16
Adding Washer Fluid
....................................... 5-38
Additional Program Information
........................... 7-8
Additives, Fuel ................................................. 5-6
Add-on Electrical Equipment
............................ 5-95
Add-on Equipment .......................................... 4-48
Off Light ..................................................... 3-28
Passenger Status Indicator
........................... 3-30
Readiness Light
.......................................... 3-27
Air Bag Systems
............................................. 1-57
Bag-Equipped Vehicle
............................... 1-72
Passenger Sensing System
........................... 1-68
Adjusting the Speakers
(Balance/Fade)
.............. 3-66
Air Bag
Adding Equipment to Your Air
Air Bag
Off Switch ....................................... 1-64
How Does an Air Bag Restrain?
.................... 1-62
Servicing Your Air Bag-Equipped Vehicle
......... 1-72
What Makes an
Air Bag inflate? .................... 1-61
What Will You See After an
Air Bag Inflates?
...................................... 1-62
When Should an Air Bag Inflate?
................... 1-61
Where Are the Air Bags?
.............................. 1-59
Air Cleaner/FiIter, Engine
................................. 5-1 9
All Overseas Locations ...................................... 7-4
All-Wheel Drive
............................................... 5-49
All-Wheel Drive (AWD) System
......................... 2-21
Aluminum or Chrome-Plated Wheels
.................. 5-90
AM ............................................................ 3-82
Antenna, Fixed Mast
....................................... 3-84
Anti-lock Brake System
..................................... 4-7
Appearance Care
............................................ 5-86
Care of Safety Belts
.................................... 5-88
Antenna,
XMTM Satellite
Radio System ............... 3-84
Anti-Lock Brake, System Warning
Light .............. 3-35
Chemical Paint Spotting
............................... 5-91
Cleaning the Inside of Your Vehicle
................ 5-86
Cleaning the Outside of Your Vehicle
.............. 5-88
Finish Damage
............................................ 5-91
GM Vehicle Care/Appearance Materials .......... 5-92
Sheet Metal Damage
................................... 5-91
Underbody Maintenance
............................... 5-91
Weatherstrips
.............................................. 5-88
Ashtrays
........................................................ 3-17
Audio System(s)
............................................. 3-61
Audio Systems
Audio Steering Wheel Controls
...................... 3-81
Care of Your Cassette Tape Player
................ 3-83
Care of Your CD Player
............................... 3-84
Care of Your CDs
........................................ 3-84
CD Changer
............................................... 3-78
DAB Radio Antenna System
.......................... 3-84
Fixed Mast Antenna
..................................... 3-84
Radio with Cassette and CD
......................... 3-62
Rear Seat Audio (RSA)
................................ 3-76
Setting the Time
.......................................... 3-61
Theft-Deterrent Feature
................................ 3-81
Understanding Radio Reception
..................... 3-82
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