2003 GMC YUKON DENALI hood open

Engine Coolant Heater
Your vehicle may be equipped with an engine
coolant heater.
I
Usually, the coolant heater sho In very cold weather,
0°F
(-18°C) or
colder, the
engine coolant heater can
help. You’ll get easier
starting and better
fuel economy during
engine warm-up.
luld be ph Jgged in a
minimum of four hours prior to starting your vehicle.
At temperatures above 32°F (OOC), use of the coolant
heater is not required.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord.
The cord is located on the driver’s side of the
engine compartment, near the power steering
fluid reservoir. 3.
Plug it into a normal, grounded 1 IO-volt AC outlet.
PIL,ging the cord inl, an ,..grc,.lded out.,_
could cause an electrical shock. Also, the
wrong kind
of extension cord could overheat
and cause a fire. You could be seriously
injured. Plug the cord into a properly grounded
three-prong
11 0-volt AC outlet. If the cord
won’t reach, use a heavy-duty three-prong
extension cord rated for at least
15 amps.
4. Before starting the engine, be sure to unplug and
store the cord as it was before to keep it away
from moving engine parts.
If you don’t, it could be
damaged.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead
of trying to list everything here, we ask that you contact
your dealer in the area where you’ll be parking your
vehicle. The dealer can give you the best advice for that
particular area.
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Outlet Adjustment
Use the air outlets located in the center and on the side
of your instrument panel to direct the airflow.
Your vehicle has air outlets that allow you to adjust the
direction and amount of airflow inside the vehicle.
Move the louvers up or down. Use the thumbwheel next
to or underneath the outlet
to close the louvers. For
the most efficient airflow and temperature control, keep
the outlet in the fully opened position.
Operation Tips
e
e
Keep the hood and front air inlets free of ice, snow,
or any other obstruction (such as leaves). The
heater and defroster will work far better, reducing
the chance of fogging the inside of your windows.
Keep the air path under the front seats clear
of objects. This helps air to circulate throughout
your vehicle.
Adding outside equipment
to the front of your
vehicle, such as hood-air deflectors, etc., may affect
the performance of the heating and air conditioning
system. Check with your dealer before adding
equipment to the outside of your vehicle.
Rear Climate Control System
With this system the front or rear passengers can
control the air temperature, air flow and fan speed for
the rear seat passengers. The climate control has
an overhead control near the driver and a control on the
back of the center console.
Driver Overhead Control
I/
I
Front Controls
To control the rear climate control from the front seat
position, use the driver overhead control. The rear
console control must be on.
3-25

California Fuel
If your vehicle is certified to meet California Emission
Standards (see the underhood emission control label), it
is designed
to operate on fuels that meet California
specifications.
If this fuel is not available in states
adopting California emissions standards, your vehicle
will operate satisfactorily on fuels meeting federal
specifications, but emission control system performance
may be affected. The malfunction indicator lamp may
turn on (see Malfunction Indicator Lamp on page
3-38 )
and your vehicle may fail a smog-check test. If this
occurs, return
to your authorized GM dealer for
diagnosis.
If it is determined that the condition is caused
by the type of fuel used, repairs may not be covered
by your warranty.
Additives
To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent engine and fuel system deposits from forming,
allowing your emission control system
to work
properly. You should not have
to add anything to your
fuel. Gasolines containing oxygenates, such as ethers and ethanol, and reformulated gasolines may be
available in your area to contribute
to clean air.
General Motors recommends that you use these
gasolines, particularly
if they comply with the
specifications described earlier.
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Notice: Your vehicle was not designed for fuel that
contains methanol. Don’t use fuel containing
methanol. It can corrode metal parts in your fuel
system and also damage the plastic and rubber
parts. That damage wouldn’t be covered under your
warranty.
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.
Fuels in Foreign Countries
If you plan on driving in another country outside the
United States or Canada, the proper fuel may be hard
to find. Never use leaded gasoline or any other fuel
not recommended in the previous text on fuel. Costly
repairs caused by use of improper fuel wouldn’t 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’ll be driving.

Checking Things Under
the
Hood
- .lings It burn can get c hot engine parts
and start a fire. These include liquids like fuel,
oil, coolant, brake fluid, windshield washer and
other fluids, and plastic or rubber.
You or
others could be burned. Be careful not to drop
or spill things that will burn onto
a hot engine.
Hood Release
To open the hood, do the following:
1. Pull the handle located
inside the vehicle
to
the lower left of
the steering wheel.
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Engine Compartment Overview
When you open the hood on the VORTECTM 6000 V8 engine you will see the following:
5-1 2

If Steam Is Coming From Your Engine
L
Steam from an overheated engine can burn
you badly, even if you just open the hood. Stay
away from the engine if you see or hear steam
coming from
it. Just turn it off and get
everyone away from the vehicle until
it cools
CAUTION: (Continued) down. Wait until there
is no sign of steam or
coolant before you open the hood.
If you
keep driving when your engine is
overheated, the liquids in it can catch fire. You
or others could be badly burned. Stop your
engine if
it overheats, and get out of the
vehicle until the engine is cool.
See “Overheated Engine Protection Operating
Mode” in the Index for information on driving
to a safe place
in an emergency.
Notice: If your engine catches fire because you
keep driving with no coolant, your vehicle can
be badly damaged. The costly repairs would not be
covered by your warranty. See “Overheated
Engine Protection Operating Mode” in the Index for
information on driving to a safe place in an
emergency.
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If No Steam Is Coming From Your
Engine
An overheat warning, along with a low coolant message,
can indicate a serious problem. See
Low Coolant
Level Warning Message under DIC Warnings and
Messages
on page 3-52.
If you get an engine overheat warning but see or hear
no steam, the problem may not be
too serious.
Sometimes the engine can get a little
too hot when you:
0 Climb a long hill on a hot day.
Stop after high-speed driving.
0 Idle for long periods in traffic.
0 Tow a trailer. See Towing a Trailer on page 4-47.
If you get the overheat warning with no sign of steam, try
this for a minute or so:
1. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
If you no longer have the overheat warning, you can
drive. Just
to be safe, drive slower for about 10 minutes.
If the warning doesn’t come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there’s still no sign of steam, push down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you’re parked. If you still have the warning, turn
off the
engine and get everyone out
of the vehicle until it
cools down. Also, see “Overheated Engine Protection
Operating Mode” listed previously in this section.
You may decide not
to lift the hood but to get service
help right away.
2. If you’re in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
- DRIVE (D).
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Notice: If the other system isn’t a 12-volt system
with a negative ground, both vehicles can be
damaged.
2.
Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren’t touching
each other.
If they are, it could cause a ground
connection you don’t want. You wouldn’t be able
to
start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake firmly on both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL before setting the parking brake.
Notice: If you leave your radio on, it could be badly
damaged. The repairs wouldn’t be covered by
your warranty.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn
off the
radio and all lamps that aren’t needed. This
will avoid sparks and help save both batteries.
And it could save your radio!
4. Open the hoods and locate the positive (+) and
negative
(-) terminal locations of the other vehicle.
Your vehicle has a remote positive
(+) jump
starting terminal and a remote negative
(-) jump
starting terminal.
You should always use these
remote terminals instead
of the terminals on the
battery.
The remote positive
(+)
terminal is located under a red plastic cover near
the engine accessory drive
bracket.
To access the
remote positive
(+)
terminal, open the red
plastic cover.
5-41