2003 GMC SONOMA maintenance

Seats and Restraint Systems........................... 1-1
Front Seats
............................................... 1-3
Rear Seats
............................................... 1-9
Safety Belts
.............................................1-10
Child Restraints
.......................................1-30
Air Bag System
.......................................1-54
Restraint System Check
............................1-64
Features and Controls..................................... 2-1
Keys
........................................................ 2-3
Doors and Locks
....................................... 2-8
Windows
.................................................2-14
Theft-Deterrent Systems
............................2-17
Starting and Operating Your Vehicle
...........2-20
Mirrors
....................................................2-39
Storage Areas
.........................................2-41
Sunroof
..................................................2-52
Vehicle Personalization
.............................2-54
Instrument Panel............................................. 3-1
Instrument Panel Overview
.......................... 3-2
Climate Controls
......................................3-17
Warning Lights, Gages and Indicators
.........3-20
Audio System(s)
.......................................3-36
Driving Your Vehicle....................................... 4-1
Your Driving, the Road, and Your Vehicle
..... 4-2
Towing
...................................................4-42Service and Appearance Care.......................... 5-1
Service
..................................................... 5-3
Fuel
......................................................... 5-4
Checking Things Under the Hood
................. 5-8
Rear Axle
...............................................5-47
Four-Wheel Drive
.....................................5-48
Front Axle
...............................................5-49
Bulb Replacement
....................................5-50
Windshield Wiper Blade Replacement
.........5-56
Tires
......................................................5-58
Appearance Care
.....................................5-79
Vehicle Identification
.................................5-87
Electrical System
......................................5-88
Capacities and Specifications
.....................5-94
Normal Maintenance Replacement Parts
......5-96
Maintenance Schedule..................................... 6-1
Maintenance Schedule
................................ 6-2
Customer Assistance Information.................... 7-1
Customer Assistance Information
.................. 7-2
Reporting Safety Defects
............................ 7-8
Index................................................................ 1
2003 GMC Sonoma Owner ManualM
2003 - Sonoma Owner Manual

Servicing Your Air Bag-Equipped
Vehicle
Air bags affect how your vehicle should be serviced.
There are parts of the air bag system in several places
around your vehicle. You don’t want the system to
inflate while someone is working on your vehicle.
Your dealer and the service manual have information
about servicing your vehicle and the air bag system.
To purchase a service manual, seeService Publications
Ordering Information on page 7-9.
{CAUTION:
For up to 10 minutes after the ignition key is
turned off and the battery is disconnected, an
air bag can still inate during improper service.
You can be injured if you are close to an air bag
when it inates. Avoid wires wrapped with
yellow tape or yellow connectors. They are
probably part of the air bag system. Be sure to
follow proper service procedures, and make
sure the person performing work for you is
qualied to do so.
The air bag system does not need regular maintenance.
Adding Equipment to Your Air
Bag-Equipped Vehicle
Q:If I add a push bumper or a bicycle rack to the
front of my vehicle, will it keep the air bags
from working properly?
A:As long as the push bumper or bicycle rack is
attached to your vehicle so that the vehicle’s
basic structure isn’t changed, it’s not likely to keep
the air bags from working properly in a crash.
Q:Is there anything I might add to the front of the
vehicle that could keep the air bags from
working properly?
A:Yes. If you add things that change your vehicle’s
frame, bumper system, front end sheet metal or
height, they may keep the air bag system
from working properly. Also, the air bag system
may not work properly if you relocate any of the air
bag sensors. If you have any questions about
this, you should contact Customer Assistance
before you modify your vehicle. The phone
numbers and addresses for Customer Assistance
are in Step Two of theCustomer Satisfaction
Procedure on page 7-2.
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2003 - Sonoma OM

Restraint System Check
Checking Your Restraint Systems
Now and then, make sure the safety belt reminder light
and all your belts, buckles, latch plates, retractors
and anchorages are working properly. Look for any other
loose or damaged safety belt system parts. If you see
anything that might keep a safety belt system from doing
its job, have it repaired.
Torn or frayed safety belts may not protect you in a
crash. They can rip apart under impact forces. If a belt
is torn or frayed, get a new one right away.
Also look for any opened or broken air bag covers, and
have them repaired or replaced. (The air bag system
does not need regular maintenance.)
Replacing Restraint System Parts
After a Crash
{CAUTION:
A crash can damage the restraint systems in
your vehicle. A damaged restraint system may
not properly protect the person using it,
resulting in serious injury or even death in a
crash. To help make sure your restraint
systems are working properly after a crash,
have them inspected and any necessary
replacements made as soon as possible.
If you’ve had a crash, do you need new belts or LATCH
system parts?
After a very minor collision, nothing may be necessary.
But if the belts were stretched, as they would be if
worn during a more severe crash, then you need
new parts.
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2003 - Sonoma OM

The SERVICE ENGINE SOON or CHECK ENGINE light
comes on to indicate that there is a problem and
service is required. Malfunctions often will be indicated
by the system before any problem is apparent. This
may prevent more serious damage to your vehicle. This
system is also designed to assist your service
technician in correctly diagnosing any malfunction.
Notice:If you keep driving your vehicle with this
light on, after a while, your emission controls
may not work as well, your fuel economy may not
be as good and your engine may not run as
smoothly. This could lead to costly repairs that may
not be covered by your warranty.
Notice:Modications made to the engine,
transmission, exhaust, intake or fuel system of your
vehicle or the replacement of the original tires
with other than those of the same Tire Performance
Criteria (TPC) can affect your vehicle’s emission
controls and may cause this light to come on.
Modications to these systems could lead to costly
repairs not covered by your warranty. This may
also result in a failure to pass a required Emission
Inspection/Maintenance test.
This light should come on, as a check to show you it is
working, when the ignition is on and the engine is not
running. If the light doesn’t come on, have it repaired.This light will also come on during a malfunction in one of
two ways:
Light Flashing—Amisre condition has been
detected. A misre increases vehicle emissions and
may damage the emission control system on your
vehicle. Diagnosis and service may be required.
Light On Steady—An emission control system
malfunction has been detected on your vehicle.
Diagnosis and service may be required.
If the Light Is Flashing
The following may prevent more serious damage to
your vehicle:
Reducing vehicle speed.
Avoiding hard accelerations.
Avoiding steep uphill grades.
If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.
If the light stopsashing and remains on steady, see
“If the Light Is On Steady”following.
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2003 - Sonoma OM

Emissions Inspection and Maintenance
Programs
Some state/provincial and local governments have or
may begin programs to inspect the emission control
equipment on your vehicle. Failure to pass this
inspection could prevent you from getting a vehicle
registration.
Here are some things you need to know to help your
vehicle pass an inspection:
Your vehicle will not pass this inspection if the SERVICE
ENGINE SOON or CHECK ENGINE light is on or not
working properly.
Your vehicle will not pass this inspection if the OBD
(on-board diagnostic) system determines that critical
emission control systems have not been completely
diagnosed by the system. The vehicle would be
considered not ready for inspection. This can happen if
you have recently replaced your battery or if your battery
has run down. The diagnostic system is designed to
evaluate critical emission control systems during normal
driving. This may take several days of routine driving.
If you have done this and your vehicle still does not pass
the inspection for lack of OBD system readiness, your
GM dealer can prepare the vehicle for inspection.
Oil Pressure Gage
The oil pressure gage shows the engine oil pressure in
psi (pounds per square inch) when the engine is
running. Canadian vehicles indicate pressure in kPa
(kilopascals).United States
Canada
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2003 - Sonoma OM

Off-Road Driving with Your
Four-Wheel-Drive Vehicle
This off-road guide is for vehicles that have four-wheel
drive.
Also, seeAnti-Lock BrakesunderBraking on page 4-5.
If your vehicle doesn’t have four-wheel drive, you
shouldn’t drive off-road unless you’re on a level, solid
surface.
Off-road driving can be great fun. But it does have
some denite hazards. The greatest of these is
the terrain itself.
'Off-roading' means you’ve left the great North American
road system behind. Traffic lanes aren’t marked.
Curves aren’t banked. There are no road signs.
Surfaces can be slippery, rough, uphill or downhill.
In short, you’ve gone right back to nature.
Off-road driving involves some new skills. And that’s
why it’s very important that you read this guide.
You’llnd many driving tips and suggestions. These will
help make your off-road driving safer and more
enjoyable.
Before You Go Off-Roading
There are some things to do before you go out. For
example, be sure to have all necessary maintenance
and service work done. Check to make sure all
underbody shields (if so equipped) are properly
attached. Be sure you read all the information about
your four-wheel-drive vehicle in this manual. Is
there enough fuel? Is the spare tire fully inated?
Are theuid levels up where they should be? What are
the local laws that apply to off-roading where you’ll
be driving? If you don’t know, you should check with law
enforcement people in the area. Will you be on
someone’s private land? If so, be sure to get the
necessary permission.
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2003 - Sonoma OM

Driving in Water
Heavy rain can meanashooding, andood waters
demand extreme caution.
Find out how deep the water is before you drive through
it. If it’s deep enough to cover your wheel hubs, axles
or exhaust pipe, don’t try it—you probably won’t
get through. Also, water that deep can damage your
axle and other vehicle parts.
If the water isn’t too deep, drive slowly through it. At faster
speeds, water splashes on your ignition system and your
vehicle can stall. Stalling can also occur if you get your
tailpipe under water. And, as long as your tailpipe is
under water, you’ll never be able to start your engine.
When you go through water, remember that when your
brakes get wet, it may take you longer to stop.
{CAUTION:
Driving through rushing water can be
dangerous.Deep water can sweep your vehicle
downstream and you and your passengers
could drown.If it’s only shallow water, it can
CAUTION: (Continued)
CAUTION: (Continued)
still wash away the ground from under your
tires, and you could lose traction and roll the
vehicle over.Don’t drive through rushing
water.
SeeDriving in Rain and on Wet Roads on page 4-28for
more information on driving through water.
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.
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2003 - Sonoma OM

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. Additional rear axle maintenance
is required for a vehicle used to tow a trailer. See
“Scheduled Maintenance Services”in the Index.Your vehicle may be able to tow a trailer. To identify
what the vehicle trailering capacity is for 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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2003 - Sonoma OM