2003 GMC SONOMA warning light

Brake Wear
If you have four-wheel drive, your vehicle has four-wheel
disc brakes. If not, your vehicle has front disc brakes
and rear drum 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 pedalfirmly).
{CAUTION:
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 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 arefirst 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.
If you have rear drum brakes, they don’t have wear
indicators, but if you ever hear a rear brake rubbing
noise, have the rear brake linings inspected immediately.
Also, the rear brake drums should be removed and
inspected each time the tires are removed for rotation or
changing. When you have the front brake pads
replaced, have the rear brakes inspected, too.
Brake linings should always be replaced as complete
axle sets.
SeeBrake System Inspection on page 6-32.Brake Pedal Travel
See your dealer if the brake pedal does not return to
normal height, or if there is a rapid increase in
pedal travel. This could be a sign of brake trouble.
Brake Adjustment
Every time you make a brake stop, your disc brakes
adjust for wear.
If you don’t have four-wheel drive and your brake
pedal goes down farther than normal, your rear drum
brakes may need adjustment. Adjust them by backing
up andfirmly applying the brakes a few times.
5-41
2003 - Sonoma OM

Uniform Tire Quality Grading
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
section width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration, which grades tires by
treadwear, traction and temperature performance.
(This applies only to vehicles sold in the United States.)
The grades are molded on the sidewalls of most
passenger car tires. The Uniform Tire Quality Grading
system does not apply to deep tread, winter-type
snow tires, space-saver or temporary use spare tires,
tires with nominal rim diameters of 10 to 12 inches
(25 to 30 cm), or to some limited-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specified government test course.
For example, a tire graded 150 would wear one and
a half (1.5) times as well on the government course as
a tire graded 100. The relative performance of tires
depends upon the actual conditions of their use,
however, and may depart significantly from the norm
due to variations in driving habits, service practices and
differences in road characteristics and climate.
Traction–AA, A, B, C
The traction grades, from highest to lowest, are AA, A,
B, and C. Those grades represent the tire’s ability
to stop on wet pavement as measured under controlled
conditions on specified government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: The traction grade
assigned to this tire is based on straight-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.
5-63
2003 - Sonoma OM

A
Accessory Power Outlets.................................3-15
Adding Equipment to Your Air Bag-Equipped
Vehicle.......................................................1-63
Adding Washer Fluid.......................................5-38
Additional Program Information........................... 7-8
Additives, Fuel................................................. 5-5
Add-On Electrical Equipment............................5-88
Add-On Equipment..........................................4-48
Adjusting the Speakers
(Balance/Fade)....................3-39, 3-42, 3-49, 3-59
After Off-Road Driving.....................................4-26
Air Bag
Off Light.....................................................3-24
Readiness Light..........................................3-24
Air Bag System..............................................1-54
Adding Equipment to Your Air Bag-Equipped
Vehicle...................................................1-63
Air Bag Off Switch.......................................1-60
How Does an Air Bag Restrain?....................1-58
Servicing Your Air Bag-Equipped Vehicle.........1-63
What Makes an Air Bag Inflate?....................1-58
What Will You See After an Air Bag
Inflates?..................................................1-58
When Should an Air Bag Inflate?...................1-57
Where Are the Air Bags?..............................1-56
Air Cleaner/Filter, Engine.................................5-18
All Overseas Locations...................................... 7-4Aluminum Wheels...........................................5-84
AM ...............................................................3-67
AM-FM Radio.................................................3-37
Antenna, Fixed Mast.......................................3-69
Anti-Lock Brake System.................................... 4-6
Anti-Lock Brake, System Warning Light..............3-28
Appearance Care............................................5-79
Care of Safety Belts....................................5-82
Chemical Paint Spotting...............................5-85
Cleaning the Inside of Your Vehicle................5-79
Cleaning the Outside of Your Vehicle..............5-82
Finish Damage............................................5-85
GM Vehicle Care/Appearance Materials..........5-86
Sheet Metal Damage...................................5-85
Underbody Maintenance
...............................5-85
Weatherstrips
..............................................5-82
Approaching a Hill
..........................................4-18
Ashtrays
........................................................3-16
Assist Handles
...............................................2-50
Audio System(s)
.............................................3-36
AM-FM Radio
.............................................3-37
Care of Your Cassette Tape Player
................3-68
Care of Your CD Player
...............................3-69
Care of Your CDs
........................................3-69
Fixed Mast Antenna
.....................................3-69
Radio with Cassette and CD
.........................3-47
Radio with CD
............................................3-40
Radio with Six-Disc CD
................................3-56
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2003 - Sonoma OM

Audio System(s) (cont.)
Setting the Time for Radios with Radio
Data Systems (RDS)................................3-37
Setting the Time for Radios without Radio
Data Systems (RDS)................................3-36
Theft-Deterrent Feature................................3-67
Understanding Radio Reception.....................3-67
Automatic Headlamp System............................3-11
Automatic Transmission...................................2-22
Fluid..........................................................5-20
Operation...................................................2-25
Automatic Transmission Check..........................6-27
Automatic Transmission Shift Lock Control
System Check.............................................6-29
B
Backing Up....................................................4-58
Battery..........................................................5-42
Battery Replacement......................................... 2-6
Battery Rundown Protection.............................3-15
Bed Rails......................................................2-52
Before Leaving on a Long Trip.........................4-33
Before You Go Off-Roading..............................4-13
Body Lubrication Service..................................6-28
Brake
Parking......................................................2-32
System Inspection.......................................6-32Brake (cont.)
System Warning Light..................................3-27
Brake Adjustment............................................5-41
Brake Fluid....................................................5-39
Brake Pedal Travel.........................................5-41
Brake Wear...................................................5-41
Brakes..........................................................5-39
Braking........................................................... 4-5
Braking in Emergencies..................................... 4-7
Break-In, New Vehicle.....................................2-20
Bulb Replacement...........................................5-50
Center High-Mounted Stoplamp (CHMSL)........5-54
Halogen Bulbs............................................5-50
Headlamps.................................................5-50
One-Piece Front Turn Signal Lamps...............5-52
Replacement Bulbs......................................5-55
Taillamps....................................................5-55
Two-Piece Front Turn Signal Lamps...............5-53
Buying New Tires...........................................5-62
C
California Fuel.................................................. 5-5
Canada........................................................... 7-4
Canadian Owners................................................ ii
Canadian Roadside Assistance........................... 7-6
Capacities and Specifications............................5-94
Carbon Monoxide...................4-36, 4-51, 2-12, 2-37
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2003 - Sonoma OM

Care of
Safety Belts................................................5-82
Your Cassette Tape Player............................3-68
Your CD Player...........................................3-69
Your CDs ...................................................3-69
Cassette Tape Messages.................................3-54
Cassette Tape Player Service...........................6-26
Center High-Mounted Stoplamp (CHMSL)...........5-54
Center Passenger Position, Safety Belts.............1-23
Chains, Tires..................................................5-66
Charging System Light....................................3-26
Check
Engine Light...............................................3-29
Gages Warning Light
...................................3-34
Checking Brake Fluid
......................................5-40
Checking Coolant
............................................5-26
Checking Engine Oil
........................................5-13
Checking the Fluid Level
..................................5-21
Checking Things Under the Hood
....................... 5-8
Checking Your Restraint Systems
......................1-64
Chemical Paint Spotting
...................................5-85
Child Restraints
Child Restraint Systems
...............................1-36
Infants and Young Children
...........................1-32
Lower Anchorages and Top Tethers for
Children (LATCH System)
..........................1-44
Older Children
.............................................1-30Child Restraints (cont.)
Securing a Child Restraint Designed for
the LATCH System...................................1-46
Securing a Child Restraint in a Center
Seat Position...........................................1-49
Securing a Child Restraint in a Rear
Outside Seat Position...............................1-46
Securing a Child Restraint in the Right
Front Seat Position...................................1-49
Top Strap...................................................1-41
Top Strap Anchor Location............................1-43
Where to Put the Restraint...................1-39, 1-40
Cigarette Lighter.............................................3-16
Cleaning
Inside of Your Vehicle..................................5-79
Outside of Your Vehicle................................5-82
Underbody Maintenance...............................5-85
Weatherstrips..............................................5-82
Cleaning Exterior Lamps/Lenses.......................5-83
Cleaning the Mirror.........................................2-39
Cleaning the Photocells...................................2-39
Climate Control System...................................3-17
Outlet Adjustment........................................3-19
Clutch, Hydraulic.............................................5-24
Compact Disc Messages.................3-46, 3-56, 3-67
Compact Spare Tire........................................5-78
Content Theft-Deferrent....................................2-17
Control of a Vehicle.......................................... 4-5
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2003 - Sonoma OM

Flat Tire........................................................5-67
Flat Tire, Changing.........................................5-68
Fluid
Automatic Transmission................................5-20
Manual Transmission....................................5-23
Power Steering...........................................5-37
Windshield Washer......................................5-38
FM ...............................................................3-67
Fog Lamps ....................................................3-13
Following Distance..........................................4-57
Four-Wheel Drive....................................2-29, 5-48
Front Axle......................................................5-49
Front Map Lamps...........................................3-14
Front Storage Area.........................................2-49
Fuel............................................................... 5-4
Additives...................................................... 5-5
California Fuel.............................................. 5-5
Filling a Portable Fuel Container..................... 5-8
Filling Your Tank........................................... 5-6
Fuels in Foreign Countries.............................. 5-6
Gage .........................................................3-35
Gasoline Octane........................................... 5-4
Gasoline Specifications.................................. 5-5
Low Warning Light.......................................3-35
System Inspection
.......................................6-31
Fuses
Fuses and Circuit Breakers
...........................5-89
Windshield Wiper
.........................................5-88G
Gage
Check Gages Warning Light..........................3-34
Engine Coolant Temperature.........................3-29
Fuel..........................................................3-35
Oil Pressure...............................................3-32
Speedometer..............................................3-23
Tachometer.................................................3-23
Voltmeter Gage...........................................3-26
Garment Hooks..............................................2-50
Gasoline
Octane........................................................ 5-4
Specifications............................................... 5-5
Getting Familiar with Off-Road Driving................4-16
Glass Surfaces...............................................5-81
Glove Box.....................................................2-41
GM Mobility Program for Persons with
Disabilities.................................................... 7-5
H
Hazard Warning Flashers................................... 3-3
Head Restraints............................................... 1-7
Headlamp High/Low-Beam Changer.................... 3-6
Headlamps....................................................5-50
Bulb Replacement.......................................5-50
Electrical System.........................................5-88
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2003 - Sonoma OM

Instrument Panel Brightness.............................3-14
Instrument Panel Fuse Block............................5-89
Interior Lamps................................................3-14
Interior Plastic Components..............................5-81
J
Jump Seat.....................................................1-10
Jump Starting.................................................5-43
K
Key Lock Cylinders Service..............................6-28
Key Release Button........................................2-21
Keyless Entry System....................................... 2-4
Keys............................................................... 2-3
L
Lamps
Exterior......................................................3-10
Interior.......................................................3-14
Lamps On Reminder.......................................3-12
Lap Belt................................................1-23, 1-25
Lap-Shoulder Belt...........................................1-16LATCH System
Child Restraints
...........................................1-44
Securing a Child Restraint Designed for the
LATCH System
........................................1-46
Latches, Seatback
............................................ 1-8
Leather
.........................................................5-81
Leaving Your Vehicle
.......................................2-11
Leaving Your Vehicle With the Engine Running
. . . 2-34
Light
Air Bag Off
.................................................3-24
Air Bag Readiness
.......................................3-24
Anti-Lock Brake System Warning
...................3-28
Brake System Warning
.................................3-27
Charging System
.........................................3-26
Check Gages Warning
.................................3-34
Low Fuel Warning
.......................................3-35
Malfunction Indicator
....................................3-29
Safety Belt Reminder
...................................3-23
Security
.....................................................3-33
Service Four-Wheel-Drive Warning Light
.........3-34
Up-Shift
.....................................................3-27
Loading Your Vehicle
.......................................4-46
Loading Your Vehicle for Off-Road Driving
..........4-14
Locking Rear Axle
............................................ 4-7
Lockout Protection
..........................................2-11
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2003 - Sonoma OM

Locks
Door ........................................................... 2-8
Leaving Your Vehicle....................................2-11
Lockout Protection.......................................2-11
Power Door .................................................. 2-9
Programmable Automatic Door Locks............... 2-9
Rear Door Security Locks.............................2-11
Long Trip/Highway Definition.............................. 6-6
Long Trip/Highway Intervals............................... 6-6
Long Trip/Highway Scheduled Maintenance........6-18
Loss of Control...............................................4-12
Low Fuel Warning Light...................................3-35
Luggage Carrier..............................................2-50
Lumbar
Manual Controls............................................ 1-4
Power Controls............................................. 1-5
M
Maintenance, Normal Replacement Parts............5-96
Maintenance Schedule
At Each Fuel Fill.........................................6-26
At Least Four Times a Year..........................6-27
At Least Once a Month................................6-26
At Least Once a Year..................................6-28
At Least Twice a Year..................................6-26Maintenance Schedule (cont.)
Brake System Inspection..............................6-32
Engine Cooling System Inspection.................6-31
Exhaust System Inspection...........................6-31
Fuel System Inspection................................6-31
How This Section is Organized....................... 6-3
Introduction.................................................. 6-2
Long Trip/Highway Scheduled Maintenance.....6-18
Maintenance Requirements............................. 6-2
Part A - Scheduled Maintenance Services......... 6-4
Part B - Owner Checks and Services.............6-26
Part C - Periodic Maintenance Inspections......6-31
PartD-Recommended Fluids and
Lubricants...............................................6-33
PartE-Maintenance Record........................6-35
Selecting the Right Schedule
.......................... 6-5
Short Trip/City Scheduled Maintenance
............. 6-7
Steering, Suspension and Front Drive
Axle Boot and Seal Inspection
...................6-31
Throttle System Inspection
............................6-32
Transfer Case and Front Axle
(Four-Wheel Drive) Inspection
....................6-32
Using Your
................................................... 6-4
Your Vehicle and the Environment
................... 6-2
Maintenance When Trailer Towing
.....................4-60
Making Turns
.................................................4-58
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2003 - Sonoma OM