2003 CHEVROLET AVALANCHE check engine

Remember: Anti-lock doesn't change the time you need
to get your foot up to the brake pedal or always
decrease stopping distance. If you get too close to the
vehicle in front of you, you won't have time to apply
your brakes if that vehicle suddenly slows or stops.
Always leave enough room up ahead to stop, even
though you have anti-lock brakes.
Using Anti-Lock
Don't pump the brakes. Just hold the brake pedal down
®rmly and let anti-lock work for you. You may feel
the brakes vibrate, or you may notice some noise, but
this is normal.
Braking in Emergencies
With anti-lock, you can steer and brake at the same
time. In many emergencies, steering can help you more
than even the very best braking.
Supplemental Brake Assist System
If your vehicle has vacuum assist power brakes, it is also
equipped with a supplemental brake assist system
that supplies additional vacuum to the vacuum brake
booster if engine vacuum is reduced. Under certain
conditions, the supplemental brake assist system may
run brie¯y after starting your vehicle or when you
apply and release the brake pedal and it may continue
to run even after you have removed your foot from
the brake pedal. When the supplemental brake assistsystem is operating, you may hear a motor running or
feel a slight vibration in the steering wheel or brake
pedal. This indicates that the supplemental brake assist
system is working to supply additional vacuum for
your vacuum assist power brakes. This is a normal
operation of your brake system and does not require that
the brake system be serviced.
Each time you start your vehicle and accelerate to 10
mph, the supplemental brake assist system will perform
a self-diagnostic check of the system and you may
hear or feel the supplemental brake assist motor run
brie¯y. While you are driving your vehicle, the
supplemental brake assist system monitors itself to
ensure that it is operating properly. If there is a problem
with the supplemental brake assist system, the
SERVICE BRAKE BOOSTER message will be displayed
on the Driver Information Center. See
DIC Warnings
and Messages on page 3-57.
If your supplemental brake assist system runs every
time you apply and release the brake pedal or you notice
that the brake pedal has suddenly become much
harder to push and the vehicle takes longer to stop, you
should have your vehicle serviced as soon as possible.
4-9

StabilitrakžSystem
Your vehicle may be equipped with Stabilitrakžwhich
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 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.
4-12

Once you are moving on the freeway, make certain you
allow a reasonable following distance. Expect to
move slightly slower at night.
When you want to leave the freeway, move to the
proper lane well in advance. If you miss your exit, do
not, under any circumstances, stop and back up. Drive
on to the next exit.
The exit ramp can be curved, sometimes quite sharply.
The exit speed is usually posted.
Reduce your speed according to your speedometer, not
to your sense of motion. After driving for any distance
at higher speeds, you may tend to think you are
going slower than you actually are.
Before Leaving on a Long Trip
Make sure you're ready. Try to be well rested. If you
must start when you're not fresh Ð such as after a day's
work Ð don't plan to make too many miles that ®rst
part of the journey. Wear comfortable clothing and shoes
you can easily drive in.Is your vehicle ready for a long trip? If you keep it
serviced and maintained, it's ready to go. If it needs
service, have it done before starting out. Of course,
you'll ®nd experienced and able service experts in GM
dealerships all across North America. They'll be
ready and willing to help if you need it.
Here are some things you can check before a trip:
·Windshield Washer Fluid:Is the reservoir full? Are
all windows clean inside and outside?
·Wiper Blades:Are they in good shape?
·Fuel, Engine Oil, Other Fluids:Have you checked
all levels?
·Lamps:Are they all working? Are the lenses clean?
·Tires:They are vitally important to a safe,
trouble-free trip. Is the tread good enough for
long-distance driving? Are the tires all in¯ated to the
recommended pressure?
·Weather Forecasts:What's the weather outlook
along your route? Should you delay your trip a
short time to avoid a major storm system?
·Maps:Do you have up-to-date maps?
4-38

Highway Hypnosis
Is there actually such a condition as ªhighway
hypnosisº? Or is it just plain falling asleep at the wheel?
Call it highway hypnosis, lack of awareness, or
whatever.
There is something about an easy stretch of road with
the same scenery, along with the hum of the tires on the
road, the drone of the engine, and the rush of the
wind against the vehicle that can make you sleepy. Don't
let it happen to you! If it does, your vehicle can leave
the road in
less than a second,and you could crash and
be injured.
What can you do about highway hypnosis? First, be
aware that it can happen.
Then here are some tips:
·Make sure your vehicle is well ventilated, with a
comfortably cool interior.
·Keep your eyes moving. Scan the road ahead and
to the sides. Check your mirrors and your
instruments frequently.
·If you get sleepy, pull off the road into a rest,
service or parking area and take a nap, get some
exercise, or both. For safety, treat drowsiness
on the highway as an emergency.
Hill and Mountain Roads
Driving on steep hills or mountains is different from
driving in ¯at or rolling terrain.
4-39

If you drive regularly in steep country, or if you're
planning to visit there, here are some tips that can make
your trips safer and more enjoyable. See
Off-Road
Driving with Your Four-Wheel-Drive Vehicle on
page 4-19
for information about driving off-road.
·Keep your vehicle in good shape. Check all ¯uid
levels and also the brakes, tires, cooling system
and transmission. These parts can work hard
on mountain roads.
·Know how to go down hills. The most important
thing to know is this: let your engine do some of
the slowing down. Shift to a lower gear when you go
down a steep or long hill.
{CAUTION:
If you don't shift down, your brakes could get
so hot that they wouldn't work well. You would
then have poor braking or even none going
down a hill. You could crash. Shift down to let
your engine assist your brakes on a steep
downhill slope.
{CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. Your brakes will have
to do all the work of slowing down. They could
get so hot that they wouldn't work well. You
would then have poor braking or even none
going down a hill. You could crash. Always
have your engine running and your vehicle in
gear when you go downhill.
4-40

{CAUTION:
Snow can trap exhaust gases under your
vehicle. This can cause deadly CO (carbon
monoxide) gas to get inside. CO could
overcome you and kill you. You can't see it or
smell it, so you might not know it is in your
vehicle. Clear away snow from around the
base of your vehicle, especially any that is
blocking your exhaust pipe. And check around
again from time to time to be sure snow
doesn't collect there.
Open a window just a little on the side of the
vehicle that's away from the wind. This will
help keep CO out.
Run your engine only as long as you must. This saves
fuel. When you run the engine, make it go a little
faster than just idle. That is, push the accelerator
slightly. This uses less fuel for the heat that you get and
it keeps the battery charged. You will need a
well-charged battery to restart the vehicle, and possibly
for signaling later on with your headlamps. Let the
heater run for a while.Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine
again and repeat this only when you feel really
uncomfortable from the cold. But do it as little as
possible. Preserve the fuel as long as you can. To help
keep warm, you can get out of the vehicle and do
some fairly vigorous exercises every half hour or so until
help comes.
If You Are Stuck: In Sand, Mud, Ice
or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you don't want to spin your
wheels too fast. The method known as ªrockingº can
help you get out when you're stuck, but you must
use caution.
4-45

5. If you have a four-wheel-drive vehicle, be sure the
transfer case is in a drive gear and not in
NEUTRAL (N).
6. Release the regular brakes.
{CAUTION:
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake ®rmly set. Your vehicle can
roll.
If you have left the engine running, the vehicle
can move suddenly. You or others could be
injured. To be sure your vehicle won't move,
even when you're on fairly level ground, use
the steps that follow.
Always put the shift lever fully in PARK (P)
with the parking brake ®rmly set.
If the transfer case on four-wheel-drive
vehicles is in NEUTRAL, your vehicle will be
free to roll, even if your shift lever is in PARK
(P). So, be sure the transfer case is in a drive
gear Ð not in NEUTRAL.
When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
·start your engine,
·shift into a gear, and
·release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you're
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission ¯uid (don't over®ll),
engine oil, axle lubricant, belts, cooling system and
brake system. Each of these is covered in this manual,
and the Index will help you ®nd them quickly. If
you're trailering, it's a good idea to review these sections
before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
4-67

Service............................................................5-3
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside of Your
Vehicle......................................................5-4
Fuel................................................................5-5
Gasoline Octane............................................5-5
Gasoline Speci®cations....................................5-5
California Fuel...............................................5-6
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-7
Filling Your Tank............................................5-7
Filling a Portable Fuel Container.......................5-9
Checking Things Under the Hood....................5-10
Hood Release..............................................5-10
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-15
Engine Air Cleaner/Filter................................5-20
Automatic Transmission Fluid.........................5-22
Engine Coolant.............................................5-24
Coolant Surge Tank Pressure Cap..................5-27
Engine Overheating.......................................5-27
Cooling System............................................5-30
Engine Fan Noise.........................................5-36Power Steering Fluid.....................................5-36
Windshield Washer Fluid................................5-38
Brakes........................................................5-39
Battery........................................................5-42
Jump Starting...............................................5-43
Rear Axle.......................................................5-49
Four-Wheel Drive............................................5-50
Front Axle......................................................5-51
Bulb Replacement..........................................5-52
Halogen Bulbs..............................................5-52
Headlamps..................................................5-52
Front Turn Signal, Sidemarker and Parking
Lamps.....................................................5-55
Front Turn Signal, Sidemarker and Daytime
Running Lamps.........................................5-56
Daytime Running Lamps................................5-58
Center High-Mounted Stoplamp (CHMSL).........5-58
Taillamps.....................................................5-58
Replacement Bulbs.......................................5-59
Windshield Wiper Blade Replacement..............5-60
Section 5 Service and Appearance Care
5-1