2008 GMC YUKON DENALI octane

If the Light is Flashing
The following can prevent more serious damage to your
vehicle:
Reduce vehicle speed.
Avoid hard accelerations.
Avoid 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 stops ashing and remains on steady, see “If
the Light Is On Steady” following.
If the light continues to ash, when it is safe to do so,
stop the vehicle. Find a safe place to park the vehicle.
Turn the ignition off, wait at least 10 seconds, and restart
the engine. If the light remains on steady, see “If the
Light Is On Steady” following. If the light is still ashing,
follow the previous steps and see your dealer/retailer
for service as soon as possible.
If the Light Is On Steady
You might 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. SeeFilling the Tank on page 5-7. The
diagnostic system can determine if the fuel cap has
been left off or improperly installed. A loose or missing
fuel cap allows 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 vehicle’s electrical system might be wet. The
condition is usually 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 causes
the engine not to run as efficiently as designed. You
might notice this as stalling after start-up, stalling when
you put the vehicle into gear, misring, hesitation on
acceleration, or stumbling on acceleration — these
conditions might go away once the engine is warmed up.
This will be detected by the system and cause the light to
turn on.
3-43

Service............................................................5-3
Accessories and Modications..........................5-3
California Proposition 65 Warning.....................5-3
California Perchlorate Materials Requirements.....5-4
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 Specications....................................5-5
California Fuel...............................................5-5
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-6
Filling the 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...................................................5-13
Engine Oil Life System..................................5-16
Engine Air Cleaner/Filter................................5-17
Automatic Transmission Fluid.........................5-20
Engine Coolant.............................................5-23
Coolant Surge Tank Pressure Cap..................5-26
Engine Overheating.......................................5-26
Overheated Engine Protection
Operating Mode........................................5-28Cooling System............................................5-29
Engine Fan Noise.........................................5-34
Power Steering Fluid.....................................5-34
Windshield Washer Fluid................................5-35
Brakes........................................................5-36
Battery........................................................5-39
Jump Starting...............................................5-40
All-Wheel Drive..............................................5-45
Rear Axle.......................................................5-46
Front Axle......................................................5-47
Headlamp Aiming...........................................5-48
Bulb Replacement..........................................5-50
Halogen Bulbs..............................................5-50
Taillamps, Turn Signal, Stoplamps and
Back-up Lamps.........................................5-51
License Plate Lamp......................................5-52
Replacement Bulbs.......................................5-52
Windshield Wiper Blade Replacement..............5-53
Tires..............................................................5-55
Tire Sidewall Labeling...................................5-56
Tire Terminology and Denitions.....................5-58
Ination - Tire Pressure.................................5-60
High-Speed Operation...................................5-62
Tire Pressure Monitor System.........................5-62
Tire Pressure Monitor Operation.....................5-64
Section 5 Service and Appearance Care
5-1

Fuel
Use of the recommended fuel is an important part of the
proper maintenance of your vehicle. To help keep the
engine clean and maintain optimum vehicle
performance, we recommend the use of gasoline
advertised as TOP TIER Detergent Gasoline.
Gasoline Octane
Use premium unleaded gasoline with a posted octane
rating of 91 or higher. You can also use regular
unleaded gasoline rated at 87 octane or higher, but
your vehicle’s acceleration could be slightly reduced,
and you might notice a slight audible knocking noise,
commonly referred to as spark knock. If the octane is less
than 87, you might notice 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 could
damage the engine. If you are using gasoline rated at 87
octane or higher and you hear heavy knocking, the
engine needs service.
Gasoline Specications
At a minimum, gasoline should meet ASTM specication
D 4814 in the United States or CAN/CGSB-3.5 or 3.511
in Canada. Some gasolines contain an octane-enhancing
additive called methylcyclopentadienyl manganese
tricarbonyl (MMT). We recommend against the use of
gasolines containing MMT. SeeAdditives on page 5-6for
additional information.
California Fuel
If your vehicle is certied to meet California Emissions
Standards, it is designed to operate on fuels that meet
California specications. See the underhood emission
control label. If this fuel is not available in states adopting
California emissions standards, your vehicle will operate
satisfactorily on fuels meeting federal specications, but
emission control system performance might be affected.
The malfunction indicator lamp could turn on and your
vehicle might fail a smog-check test. SeeMalfunction
Indicator Lamp on page 3-42. If this occurs, return to your
authorized dealer/retailer for diagnosis. If it is determined
that the condition is caused by the type of fuel used,
repairs might not be covered by your warranty.
5-5

Additives
To provide cleaner air, all gasolines in the United States
are now required to contain additives that help prevent
engine and fuel system deposits from forming, allowing
the emission control system to work properly. In most
cases, you should not have to add anything to the fuel.
However, some gasolines contain only the minimum
amount of additive required to meet U.S. Environmental
Protection Agency regulations. To help keep fuel injectors
and intake valves clean, or if your vehicle experiences
problems due to dirty injectors or valves, look for gasoline
that is advertised as TOP TIER Detergent Gasoline. Also,
your dealer/retailer has additives that will help correct and
prevent most deposit-related problems.
Gasolines containing oxygenates, such as ethers and
ethanol, and reformulated gasolines might be available
in your area. We recommend that you use these
gasolines, if they comply with the specications described
earlier. However, E85 (85% ethanol) and other fuels
containing more than 10% ethanol must not be used in
vehicles that were not designed for those fuels.
Notice:Your vehicle was not designed for fuel that
contains methanol. Do not use fuel containing
methanol. It can corrode metal parts in the fuel
system and also damage plastic and rubber parts.
That damage would not be covered under your
warranty.Some gasolines that are not reformulated for low
emissions can contain an octane-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask the attendant where you buy gasoline
whether the fuel contains MMT. We recommend against
the use of such gasolines. Fuels containing MMT can
reduce the life of spark plugs and the performance of the
emission control system could be affected. The
malfunction indicator lamp might turn on. If this occurs,
return to your dealer/retailer for service.
Fuels in Foreign Countries
If you plan on driving in another country outside the
United States or Canada, the proper fuel might be hard
to nd. Never use leaded gasoline or any other fuel
not recommended in the previous text on fuel. Costly
repairs caused by use of improper fuel would not be
covered by your warranty.
To check the fuel availability, ask an auto club, or
contact a major oil company that does business in the
country where you will be driving.
5-6

This schedule is for vehicles that:
carry passengers and cargo within recommended
limits. You will nd these limits on the Tire and
Loading Information label. SeeLoading Your
Vehicle on page 4-34.
are driven on reasonable road surfaces within legal
driving limits.
are driven off-road in the recommended manner.
SeeOff-Road Driving on page 4-13.
use the recommended fuel. SeeGasoline Octane
on page 5-5.
The services inScheduled Maintenance on page 6-4
should be performed when indicated. SeeAdditional
Required Services on page 6-6andMaintenance
Footnotes on page 6-7for further information.
{CAUTION:
Performing maintenance work on a vehicle
can be dangerous. In trying to do some jobs,
you can be seriously injured. Do your own
maintenance work only if you have the
required know-how and the proper tools and
CAUTION: (Continued)
CAUTION: (Continued)
equipment for the job. If you have any doubt,
see your dealer/retailer to have a qualied
technician do the work. SeeDoing Your Own
Service Work on page 5-4.
Some maintenance services can be complex. So,
unless you are technically qualied and have the
necessary equipment, you should have your
dealer/retailer do these jobs.
When you go to your dealer/retailer for your service
needs, you will know that trained and supported service
technicians will perform the work using genuine parts.
If you want to purchase service information, seeService
Publications Ordering Information on page 7-14.
Owner Checks and Services on page 6-9tells you what
should be checked, when to check it, and what you can
easily do to help keep your vehicle in good condition.
The proper replacement parts, uids, and lubricants to
use are listed inRecommended Fluids and Lubricants
on page 6-12andMaintenance Replacement Parts
on page 6-14. When your vehicle is serviced, make sure
these are used. All parts should be replaced and all
necessary repairs done before you or anyone else
drives the vehicle. We recommend the use of genuine
parts from your dealer/retailer.
6-3

Engine
Air Cleaner/Filter.........................................5-17
Check and Service Engine Soon Light............3-42
Coolant......................................................5-23
Coolant Heater............................................2-29
Coolant Temperature Gage...........................3-41
Drive Belt Routing.......................................6-15
Engine Compartment Overview......................5-12
Exhaust.....................................................2-38
Fan Noise..................................................5-34
Oil .............................................................5-13
Oil Life System...........................................5-16
Overheated Protection Operating Mode...........5-28
Overheating................................................5-26
Running While Parked..................................2-39
Starting......................................................2-27
Entry Lighting.................................................3-20
Event Data Recorders.....................................7-16
Exit Lighting...................................................3-20
Extender, Safety Belt.......................................1-48
Exterior Lamps...............................................3-16
F
Filter
Engine Air Cleaner......................................5-17
Finish Damage.............................................5-105
Flashers, Hazard Warning.................................. 3-6Flash-to-Pass................................................... 3-9
Flat Tire........................................................5-77
Flat Tire, Changing.........................................5-78
Flat Tire, Storing.............................................5-94
Fluid.............................................................5-20
Power Steering...........................................5-34
Windshield Washer......................................5-35
Fog Lamp
Fog ...........................................................3-19
Fog Lamp Light..............................................3-47
Front Axle......................................................5-47
Front Reading Lamps......................................3-20
Fuel............................................................... 5-5
Additives...................................................... 5-6
California Fuel.............................................. 5-5
Filling a Portable Fuel Container..................... 5-9
Filling the Tank............................................. 5-7
Fuels in Foreign Countries.............................. 5-6
Gage.........................................................3-48
Gasoline Octane........................................... 5-5
Gasoline Specications.................................. 5-5
Low Warning Light.......................................3-48
Fuses
Center Instrument Panel Fuse Block.............5-110
Fuses and Circuit Breakers.........................5-108
Instrument Panel Fuse Block.......................5-109
Underhood Fuse Block...............................5-111
Windshield Wiper.......................................5-108
5

G
Gage
Engine Coolant Temperature.........................3-41
Fuel..........................................................3-48
Oil Pressure...............................................3-45
Speedometer..............................................3-33
Tachometer.................................................3-33
Voltmeter Gage...........................................3-38
Garage Door Opener.......................................2-50
Gasoline
Octane........................................................ 5-5
Specications............................................... 5-5
Glove Box.....................................................2-58
GM Mobility Reimbursement Program.................. 7-6
H
Hazard Warning Flashers................................... 3-6
Head Restraints............................................... 1-8
Headlamp
Aiming.......................................................5-48
Headlamps
Bulb Replacement.......................................5-50
Daytime Running Lamps...............................3-17
Exterior Lamps............................................3-16
Flash-to-Pass............................................... 3-9Headlamps (cont.)
Halogen Bulbs............................................5-50
High/Low Beam Changer................................ 3-9
On Reminder..............................................3-17
Heated Seats................................................... 1-4
Heated Steering Wheel..................................... 3-7
Heater...........................................................3-23
Highbeam On Light.........................................3-47
High-Speed Operation, Tires.............................5-62
Highway Hypnosis...........................................4-27
Hill and Mountain Roads..................................4-28
Hood
Checking Things Under................................5-10
Release.....................................................5-10
Horn............................................................... 3-6
How to Wear Safety Belts Properly...................1-33I
Ignition Positions.............................................2-26
Infants and Young Children, Restraints...............1-52
Ination - Tire Pressure...................................5-60
Instrument Panel
Overview..................................................... 3-4
Storage Area..............................................2-59
6