GMC 2003 C4C042 User manual

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The 2003 GMC C-Series Owner’s Manual
1-1Seats and Restraint Systems
This section tells you how to use your seats and safety belts properly. It also explains the air bag system.
2-1Features and Controls
This section explains how to start and operate your vehicle.
3-1Comfort Controls and Audio Systems
This section tells you how to adjust the ventilation and comfort controls and how to operate your audio system.
4-1Your Driving and the Road
Here you’ll find helpful information and tips about the road and how to drive under different conditions.
5-1Problems on the Road
This section tells you what to do if you have a problem while driving, such as a flat tire or overheated engine, etc.
6-1Service and Appearance Care
Here the manual tells you how to keep your vehicle running properly and looking good.
7-1Maintenance Schedule
This section tells you when to perform vehicle maintenance and what fluids and lubricants to use.
8-1Customer Assistance Information
This section tells you how to contact GMC for assistance and how to get service and owner publications.
It also gives you information on “Reporting Safety Defects” on page 8-4.

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GENERAL MOTORS, GM, the GM Emblem, GMC
and the GMC Truck Emblem are registered trademarks
of General Motors Corporation.
This manual includes the latest information at the time
it was printed. We reserve the right to make changes
after that time without further notice. For vehicles first
sold in Canada, substitute the name “General Motors of
Canada Limited” for GM Medium Duty Truck Division
whenever it appears in this manual.
Please keep this manual in your vehicle, so it will
be there if you ever need it when you’re on the road.
If you sell the vehicle, please leave this manual in it
so the new owner can use it.
We support voluntary
technician certification.
Litho in U.S.A. E Copyright General Motors Corporation 12/03/01
Part Number X2301 A First Edition All Rights Reserved

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How to Use this Manual
Many people read their owner’s manual from
beginning to end when they first receive their new
vehicle. If you do this, it will help you learn about the
features and controls for your vehicle. In this manual,
you’ll find that pictures and words work together to
explain things quickly.
Safety Warnings and Symbols
You will find a number of safety cautions in this book.
We use a box and the word CAUTION to tell you
about things that could hurt you if you were to ignore
the warning.
CAUTION:
These mean there is something that could hurt
you or other people.
In the caution area, we tell you what the hazard is.
Then we tell you what to do to help avoid or reduce
the hazard. Please read these cautions. If you don’t,
you or others could be hurt.
You will also find a circle
with a slash through it
in this book. This safety
symbol means “Don’t,”
“Don’t do this” or “Don’t
let this happen.”

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Vehicle Damage Warnings
Also, in this book you will find these notices:
NOTICE:
These mean there is something that could damage
your vehicle.
In the notice area, we tell you about something that can
damage your vehicle. Many times, this damage would
not be covered by your warranty, and it could be costly.
But the notice will tell you what to do to help avoid
the damage.
When you read other manuals, you might see
CAUTION and NOTICE warnings in different
colors or in different words.
You’ll also see warning labels on your vehicle.
They use the same words, CAUTION or NOTICE.
Vehicle Symbols
Your vehicle may be equipped with components and
labels that use symbols instead of text. Symbols,
used on your vehicle, are shown along with the text
describing the operation or information relating to a
specific component, control, message, gage or indicator.
If you need help figuring out a specific name of a
component, gage or indicator reference the following
topics in the Index:
D “Instrument Panel”
D “Comfort Controls”
D “Audio Systems”
Also see “Warning Lights and Gages” in the Index.

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Here are some examples of symbols you may find on your vehicle:

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Model Reference
This manual contains information which covers
conventional cab models as shown. Most models
are unfinished from the factory.
C4C042
C5C042
C4V042
C5V042
C4U042
C5U042
C6C042
C7C042
C8C042
C6V042
C7V042
C8V042
C8C064
C8V064
C4E042
C5E042
C6E042
C7E042
C8E042
C8E064
Since C-Series models delivered from the factory are
finished in a variety of ways by a number of companies,
you’ll probably find other manuals in your finished
vehicle. These manuals are put there by the companies
that have added components or equipment to the
C-Series model. Read all these materials -- as well
as this manual -- carefully, to get all of the information
on your vehicle.

1- 1-1
Section 1 Seats and Restraint Systems
Here you’ll find information about the seats in your vehicle and how to use your safety belts properly. You can also
learn about some things you should not do with air bags and safety belts.
1-2 Seats and Seat Controls
1-8 Safety Belts: They’re for Everyone
1-12 Here Are Questions Many People Ask About
Safety Belts -- and the Answers
1-13 How to Wear Safety Belts Properly
1-13 Driver Position
1-21 Safety Belt Use During Pregnancy
1-22 Right Front Passenger Position
1-22 Air Bag System
1-36 Center Passenger Position
1-37 Rear Seat Passengers
1-41 Children
1-45 Restraint Systems for Children
1-64 Older Children
1-67 Safety Belt Extender
1-67 Checking Your Restraint Systems
1-68 Replacing Restraint System Parts
After a Crash

1-2
Seats and Seat Controls
This section tells you about the seats in your vehicle and
how to adjust them. It also tells you about reclining front
seatbacks.
CAUTION:
You can lose control of the vehicle if you try to
adjust the seat while the vehicle is moving. The
sudden movement could startle and confuse you,
or make you push a pedal when you don’t want
to. Adjust the driver’s seat only when the vehicle
is not moving.
Bucket Seats (If Equipped)
If your vehicle has bucket seats, also known as static
seats, you can adjust them forward or rearward with the
lever located at the front of the seat.
To adjust the seat, pull the lever up to release the seat
bottom. Slide the seat to where you want it and release
the lever. Then try to move the seat with your body, to
make sure the seat is locked in place.

1-3
Split Bench Seat (If Equipped)
If your vehicle has a split bench seat, your seat is fixed
and is not able to be adjusted.
Air Suspension Seats (If Equipped)
If your vehicle has the low-back suspension seat, there
are six ways you can adjust the seat.
If your vehicle has the high-back air suspension seat,
there are five ways you can adjust the seat.
Height Adjustment
The suspension seat height
adjustment lever is located
on the front inboard side of
the seat.
To adjust the height of the air suspension seat, pull the
lever up to inflate. Push the lever down to deflate.
The seat cushion itself can also be raised or lowered.

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The seat cushion height
adjustment handle is
located underneath the
seat, in the front.
To adjust the height of the cushion, lift the cushion
height adjustment handle up and pull it forward.
You can choose between two settings.
Lumbar Adjustments
The lumbar adjustment
knob is located on the
seatback, on the inboard
side of the driver’s seat and
on the outboard side of the
passenger’s seat.
To get more support in the lumbar area of your back,
turn the lumbar adjustment knob clockwise. To decrease
the amount of lumbar support, turn the knob
counterclockwise.

1-5
Seatback Adjustment
The seatback adjustment
knob is located on the
inboard side of the driver’s
and passenger’s seat
cushions.
To tilt the seatback rearward, turn the knob
counterclockwise. Turn the knob clockwise to
tilt the seatback forward.
Fore-and-Aft Adjustment
The fore-and-aft adjustment
lever is located underneath
the seat, in the front.
To slide the seat forward or rearward, move the
lever toward the driver’s door. The seat will lock in
at 1/2 inch (1.5 cm) increments.

1-6
Chugger-Snubber Lock-Out Feature (If Equipped)
If your vehicle has this
feature, the handle is
located on the outboard
sides of the driver’s and
passenger’s seats.
Move the handle down to minimize any backslap
experienced while in tractor/trailer operation or while
operating a dump truck application. This feature is only
available on low-back seats.
Reclining Front Seatbacks (If Equipped)
If your vehicle is equipped with bucket seats, you can
recline the seatbacks. The lever is located on the
outboard side of the seat cushion.
To recline the seatback, lift the lever and use your body
to move the seatback. Release the lever to lock the
seatback where you want it. Lean forward and pull up
on the lever to return the seatback to an upright position.

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But don’t have a seatback reclined if your vehicle
is moving.
CAUTION:
Sitting in a reclined position when your vehicle is
in motion can be dangerous. Even if you buckle
up, your safety belts can’t do their job when
you’re reclined like this.
The shoulder belt can’t do its job because it
won’t be against your body. Instead, it will be in
front of you. In a crash you could go into it,
receiving neck or other injuries.
The lap belt can’t do its job either. In a crash the
belt could go up over your abdomen. The belt
forces would be there, not at your pelvic bones.
This could cause serious internal injuries.
For proper protection when the vehicle is in
motion, have the seatback upright. Then sit well
back in the seat and wear your safety belt
properly.

1-8
Rear Seats (Crew Cab
R
)
Folding the Rear Seat
The Crew Cab’s rear bench seat can be folded down to
provide more cargo space.
To fold down the seatback,
pull this nylon strap located
on the rear of the seat, while
pulling the seatback down.
To raise a seatback, pull the nylon strap while raising the
seatback until it locks upright.
After raising a seatback to an upright position, push and
pull on the seatback to check that it is locked in place.
Safety Belts: They’re for Everyone
This part of the manual tells you how to use safety belts
properly. It also tells you some things you should not do
with safety belts.
And it explains the air bag system.
CAUTION:
Don’t let anyone ride where he or she can’t wear
a safety belt properly. If you are in a crash and
you’re not wearing a safety belt, your injuries
can be much worse. You can hit things inside the
vehicle or be ejected from it. You can be seriously
injured or killed. In the same crash, you might
not be if you are buckled up. Always fasten your
safety belt, and check that your passengers’ belts
are fastened properly too.

1-9
CAUTION:
It is extremely dangerous to ride in a cargo area,
inside or outside of a vehicle. In a collision,
people riding in these areas are more likely to be
seriously injured or killed. Do not allow people to
ride in any area of your vehicle that is not
equipped with seats and safety belts. Be sure
everyone in your vehicle is in a seat and using a
safety belt properly.
Your vehicle has a light
that comes on as a reminder
to buckle up. See “Safety
Belt Reminder Light” in
the Index.
In most states and all Canadian provinces, the law says
to wear safety belts. Here’s why: They work.
You never know if you’ll be in a crash. If you do have a
crash, you don’t know if it will be a bad one.
A few crashes are mild, and some crashes can be so
serious that even buckled up a person wouldn’t survive.
But most crashes are in between. In many of them,
people who buckle up can survive and sometimes walk
away. Without belts they could have been badly hurt
or killed.
After more than 30 years of safety belts in vehicles,
the facts are clear. In most crashes buckling up does
matter ... a lot!

1-10
Why Safety Belts Work
Q: Aren’t safety belts for kids?
A: Yes. And they’re for adult truckers, and anyone
else who rides in your vehicle.
Here’s why: when your vehicle goes, say, 30 mph
(50 km/h), so do you and your passengers.
If the vehicle hits something, it stops -- right then.
But nothing stops the people. They keep moving.

1-11
Then something will stop them. It could be the
windshield. Or it could be the instrument panel.
Now, what if you and your passengers were to give that
big vehicle a chance to deal with the force of the impact,
instead of you?

1-12
With belts, you slow down as the vehicle does. You get
more time to stop.
You stop over more distance, and your strongest bones
take the forces. Safety belts are for everyone.
Here Are Questions Many People Ask
About Safety Belts -- and the Answers
Q: Won’t I be trapped in the vehicle after an
accident if I’m wearing a safety belt?
A: You could be -- whether you’re wearing a safety
belt or not. But you can unbuckle a safety belt,
even if you’re upside down. And your chance of
being conscious during and after an accident, so
you can unbuckle and get out, is much greater if
you are belted.
Q: If my vehicle has air bags, why should I have to
wear safety belts?
A: Air bags are in many vehicles today and will be in
most of them in the future. But they are
supplemental systems only; so they work with
safety belts -- not instead of them. Every air bag
system ever offered for sale has required the use of
safety belts. Even if you’re in a vehicle that has air
bags, you still have to buckle up to get the most
protection. That’s true not only in frontal collisions,
but especially in side and other collisions.

1-13
Q: If I’m a good driver, and I never drive far from
home, why should I wear safety belts?
A: You may be an excellent driver, but if you’re in an
accident -- even one that isn’t your fault -- you
and your passengers can be hurt. Being a good
driver doesn’t protect you from things beyond your
control, such as bad drivers.
Most accidents occur within 25 miles (40 km)
of home. And the greatest number of serious
injuries and deaths occur at speeds of less
than 40 mph (65 km/h).
Safety belts are for everyone.
How to Wear Safety Belts Properly
Adults
This part is only for people of adult size.
Be aware that there are special things to know about
safety belts and children. And there are different rules
for smaller children and babies. If a child will be riding
in your vehicle, see the part of this manual called
“Children.” Follow those rules for everyone’s
protection.
First, you’ll want to know which restraint systems your
vehicle has.
We’ll start with the driver position.
Driver Position
This part describes the driver’s restraint system.
Lap-Shoulder Belt
The driver has a lap-shoulder belt. Here’s how to wear
it properly.
1. Close and lock the door.
2. Adjust the seat so you can sit up straight. To see
how, see “Seats” in the Index.