2003 CHEVROLET TAHOE octane

If the Light Is On Steady
You may be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. See
Filling Your Tank on page 5-9. The
diagnostic system can determine if the fuel cap has
been left off or improperly installed. A loose or missing
fuel cap will allow fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed
should turn the light off.
Did you just drive through a deep puddle of water?
If so, your electrical system may be wet. The condition
will usually be corrected when the electrical system
dries out. A few driving trips should turn the light off.Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel. See
Gasoline Octane on page 5-5. Poor fuel quality will
cause your engine not to run as efficiently as designed.
You may notice this as stalling after start-up, stalling
when you put the vehicle into gear, mis®ring, hesitation
on acceleration or stumbling on acceleration. (These
conditions may go away once the engine is warmed up.)
This will be detected by the system and cause the
light to turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
your dealer can check the vehicle. Your dealer has
the proper test equipment and diagnostic tools to ®x any
mechanical or electrical problems that may have
developed.
3-49

Service............................................................5-3
Doing Your Own Service Work.........................5-3
Adding Equipment to the Outside
of Your Vehicle...........................................5-4
Fuel................................................................5-4
Gasoline Octane............................................5-5
Gasoline Speci®cations....................................5-5
California Fuel...............................................5-6
Additives.......................................................5-6
Fuel E-85 (85% Ethanol).................................5-7
Fuels in Foreign Countries...............................5-8
Filling Your Tank............................................5-9
Filling a Portable Fuel Container.....................5-11
Checking Things Under
the Hood....................................................5-12
Hood Release..............................................5-12
Engine Compartment Overview.......................5-14
Engine Oil...................................................5-18
Engine Air Cleaner/Filter................................5-23
Automatic Transmission Fluid.........................5-26
Engine Coolant.............................................5-29
Coolant Surge Tank Pressure Cap..................5-32
Engine Overheating.......................................5-33Cooling System............................................5-36
Engine Fan Noise.........................................5-42
Power Steering Fluid.....................................5-43
Windshield Washer Fluid................................5-44
Brakes........................................................5-45
Battery........................................................5-48
Jump Starting...............................................5-49
All-Wheel Drive..............................................5-55
Rear Axle.......................................................5-56
Four-Wheel Drive............................................5-57
Front Axle......................................................5-58
Bulb Replacement..........................................5-59
Halogen Bulbs..............................................5-59
Headlamps..................................................5-60
Front Turn Signal, Sidemarker and Daytime
Running Lamps.........................................5-61
Side Identi®cation Marker Lamps.....................5-62
Roof Marker Lamps......................................5-62
Taillamps.....................................................5-64
Replacement Bulbs.......................................5-66
Windshield Wiper Blade Replacement..............5-66
Section 5 Service and Appearance Care
5-1

Gasoline Octane
Use regular unleaded gasoline with a posted octane of 87
or higher. If the octane is less than 87, you may get a
heavy knocking noise when you drive. If this occurs, use
a gasoline rated at 87 octane or higher as soon as
possible. Otherwise, you might damage your engine.
A little pinging noise when you accelerate or drive uphill is
considered normal. This does not indicate a problem
exists or that a higher-octane fuel is necessary. If you are
using 87 octane or higher-octane fuel and hear heavy
knocking, your engine needs service.
Gasoline Speci®cations
It is recommended that gasoline meet speci®cations
which were developed by the American Automobile
Manufacturers Association and endorsed by the
Canadian Vehicle Manufacturers Association for better
vehicle performance and engine protection. Gasoline
meeting these speci®cations could provide improved
driveability and emission control system performance
compared to other gasoline.
In Canada, look for the
ªAuto Makers' Choiceº
label on the pump.
Canada Only
5-5

Some gasolines that are not reformulated for low
emissions may contain an octane-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask the attendant where you buy gasoline
whether the fuel contains MMT. General Motors does
not recommend the use of such gasolines. Fuels
containing MMT can reduce the life of spark plugs and
the performance of the emission control system may
be affected. The malfunction indicator lamp may turn on.
If this occurs, return to your authorized GM dealer for
service.
Fuel E-85 (85% Ethanol)
The 8th digit of your vehicle identi®cation number (VIN)
shows the code letter or number that identi®es your
engine. You will ®nd the VIN at the top left of the
instrument panel. See
Vehicle Identi®cation Number
(VIN) on page 5-107.
If your vehicle has the 5.3L V8 engine (VIN Code Z
only), you may use either regular unleaded gasoline or
ethanol fuel containing up to 85% ethanol (E-85);
also see
Fuel on page 5-4. In all other engines, including
the 5.3L V8 (VIN Code T), use only regular unleaded
gasoline.Only vehicles that have the 5.3L V8 engine (VIN Code Z)
may use 85% ethanol fuel (E-85).
Many service stations will not have an 85% ethanol fuel
(E-85) pump available. The U. S. Department of
Energy has an alternative fuels website
(http://afdcmap.nrel.gov/nrel/) that can help you ®nd
E-85 fuel. Those stations that do have E-85 should have
a label indicating ethanol content. Do not use the fuel
if the ethanol content is
greaterthan 85%. Your vehicle
may not operate properly if the ethanol content is
greater than 85%.
At a minimum, E-85 should meet ASTM Speci®cation
D 5798.
To insure quick starts in the wintertime, the E-85 fuel
must be formulated properly for your climate according
to ASTM speci®cation D 5798. If you have trouble
starting on E-85, it may be because your E-85 fuel is
not properly formulated for your climate. If this happens,
switching to gasoline or adding gasoline to your fuel
tank may improve starting. Your vehicle is designed to
accommodate a mixture of gasoline and E-85 fuel.
For good starting and heater efficiency below 32ÉF
(0ÉC), the fuel mix in the fuel tank should contain no
more than 70% ethanol.
5-7

Part A: Scheduled Maintenance
Services
This part contains engine oil and chassis lubrication
scheduled maintenance which explains the engine oil life
system and how it indicates when to change the
engine oil and ®lter. Lubricate chassis components with
each oil change. Also, listed are scheduled maintenance
services which are to be performed at the mileage
intervals speci®ed.
Using Your Maintenance Schedule
We at General Motors want to help you keep your vehicle
in good working condition. But we don't know exactly how
you'll drive it. You may drive very short distances only a
few times a week. Or you may drive long distances all the
time in very hot, dusty weather. You may use your vehicle
in making deliveries. Or you may drive it to work, to do
errands or in many other ways.
Because of all the different ways people use their
vehicles, maintenance needs vary. You may need more
frequent checks and replacements. So please read
the following and note how you drive. If you have any
questions on how to keep your vehicle in good condition,
see your dealer.This part tells you the maintenance services you should
have done and when to schedule them.
When you go to your dealer for your service needs,
you'll know that GM-trained and supported service
people will perform the work using genuine GM parts.
The proper ¯uids and lubricants to use are listed in
Part D. Make sure whoever services your vehicle uses
these. All parts should be replaced and all necessary
repairs done before you or anyone else drives the
vehicle.
This schedule is for vehicles that:
·carry passengers and cargo within recommended
limits. You will ®nd these limits on your vehicle's
Certi®cation/Tire label. See
Loading Your Vehicle on
page 4-62.
·are driven on reasonable road surfaces within legal
driving limits.
·are driven off-road in the recommended manner.
See
Off-Road Driving with Your Four-Wheel-Drive
Vehicle on page 4-23.
·use the recommended fuel. SeeGasoline Octane
on page 5-5
.
6-4

Fuel............................................................... 5-4
Additives...................................................... 5-6
California Fuel.............................................. 5-6
E-85 (85% Ethanol)....................................... 5-7
Filling a Portable Fuel Container....................5-11
Filling Your Tank........................................... 5-9
Fuels in Foreign Countries.............................. 5-8
Gage.........................................................3-52
Gasoline Octane........................................... 5-5
Gasoline Speci®cations.................................. 5-5
Low Warning Light.......................................3-53
System Inspection.......................................6-16
Fuses..........................................................5-109
Fuses and Circuit Breakers.........................5-109
Windshield Wiper.......................................5-108
G
Gage............................................................3-45
Engine Coolant Temperature.........................3-45
Fuel..........................................................3-52
Oil Pressure...............................................3-50
Speedometer..............................................3-38
Tachometer.................................................3-38
Transmission Temperature.............................3-46
Voltmeter Gage...........................................3-42Garage Door Opener.......................................2-57
Gasoline......................................................... 5-5
Octane........................................................ 5-5
Speci®cations............................................... 5-5
Gate Operator and Canadian Programming........2-60
Getting Familiar with Off-Road Driving................4-28
Glove Box.....................................................2-61
GM Mobility Program for Persons with
Disabilities.................................................... 7-6
H
Hazard Warning Flashers................................... 3-6
Head Restraints............................................... 1-8
Headlamp High/Low-Beam Changer.................... 3-8
Headlamps....................................................5-60
Bulb Replacement.......................................5-59
Front Turn Signal, Sidemarker and Daytime
Running Lamps........................................5-61
Halogen Bulbs............................................5-59
Roof Marker Lamps.....................................5-62
Side Identi®cation Marker Lamps...................5-62
Headphones.................................................3-119
Heated Seats................................................... 1-5
Heating.........................................................3-29
Highway Hypnosis...........................................4-48
8