GMC YUKON 2009 Owner's Manual

{CAUTION:
An electric engine cooling fan under the hood can
start up even when the engine is not running and
can cause injury. Keep hands, clothing, and tools
away from any underhood electric fan.
{CAUTION:
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They are
under pressure, and if you turn the surge tank
pressure cap — even a little — they can come out
at high speed. Never turn the cap when the
cooling system, including the surge tank pressure
cap, is hot. Wait for the cooling system and surge
tank pressure cap to cool if you ever have to turn
the pressure cap.If no coolant is visible in the surge tank, add coolant as
follows:
1. You can remove the
coolant surge tank
pressure cap when
the cooling system,
including the coolant
surge tank pressure
cap and upper radiator
hose, is no longer hot.
Turn the pressure cap slowly counterclockwise
about one full turn. If you hear a hiss, wait for
that to stop. A hiss means there is still some
pressure left.
2. Keep turning the pressure cap slowly and remove it.
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3. Fill the coolant surge tank with the proper mixture
to the FULL COLD mark.4. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the engine
cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches the FULL COLD mark.
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5. Replace the pressure cap. Be sure the pressure
cap is hand-tight and fully seated.
6. Verify coolant level after engine is shut off and the
coolant is cold. If necessary, repeat coolant ll
procedure Steps 1 through 6.
Notice:If the pressure cap is not tightly installed,
coolant loss and possible engine damage may
occur. Be sure the cap is properly and tightly
secured.
Engine Overheating
The vehicle has several indicators to warn of engine
overheating.
There is a coolant temperature gage on your vehicle’s
instrument panel. SeeEngine Coolant Temperature
Gage on page 3-43.
In addition, ENGINE OVERHEATED STOP ENGINE,
ENGINE OVERHEATED IDLE ENGINE, and a ENGINE
POWER IS REDUCED message comes on in the
Driver Information Center (DIC) on the instrument panel.
SeeDIC Warnings and Messages on page 3-64.You may decide not to lift the hood when this warning
appears, but instead get service help right away.
SeeRoadside Assistance Program on page 7-7.
If you do decide to lift the hood, make sure the vehicle
is parked on a level surface.
Then check to see if the engine cooling fans are
running. If the engine is overheating, both fans should
be running. If they are not, do not continue to run
the engine and have the vehicle serviced.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty. See
Overheated Engine Protection Operating Mode on
page 5-37for information on driving to a safe place
in an emergency.
Notice:If the engine catches re while driving with
no coolant, the vehicle can be badly damaged.
The costly repairs would not be covered by
the vehicle warranty. SeeOverheated Engine
Protection Operating Mode on page 5-37for
information on driving to a safe place in an
emergency.
5-35

If Steam Is Coming From The Engine
Compartment
{CAUTION:
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. Turn it off and get everyone away from
the vehicle until it cools down. Wait until there
is no sign of steam or coolant before you open
the hood.
If you keep driving when the vehicles engine is
overheated, the liquids in it can catch re. You or
others could be badly burned. Stop the engine if it
overheats, and get out of the vehicle until the
engine is cool.
SeeOverheated Engine Protection Operating
Mode on page 5-37for information on driving to a
safe place in an emergency.
If No Steam Is Coming From The
Engine Compartment
The ENGINE OVERHEATED STOP ENGINE or the
ENGINE OVERHEATED IDLE ENGINE message, along
with a low coolant condition, can indicate a serious
problem.
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:
Climb a long hill on a hot day.
Stop after high-speed driving.
Idle for long periods in traffic.
Tow a trailer. SeeTowing a Trailer on page 4-52.
If you get the ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE message
with no sign of steam, try this for a minute or so:
If the overheat warning is displayed with no sign of steam:
1. Turn the air off.
2. Turn the heater on to the highest temperature and
to the highest fan speed. Open the windows as
necessary.
3. In heavy traffic, let the engine idle in N (Neutral)
while stopped. If it is safe to do so, pull off the
road, shift to P (Park) or N (Neutral) and let
the engine idle.
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If the temperature overheat gage is no longer in the
overheat zone or an overheat warning no longer
displays, the vehicle can be driven. Continue to drive
the vehicle slow for about 10 minutes. Keep a safe
vehicle distance from the car in front of you. If the
warning does not come back on, continue to drive
normally.
If the warning continues, pull over, stop, and park the
vehicle right away.
If there is no sign of steam, idle the engine for
three minutes while parked. If the warning is still
displayed, turn off the engine until it cools down.
Also, see “Overheated Engine Protection Operating
Mode” later in this section.Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
ENGINE POWER IS REDUCED message is displayed,
an overheat protection mode which alternates ring
groups of cylinders helps prevent engine damage.
In this mode, you will notice a loss in power and engine
performance. This operating mode allows the vehicle
to be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair the
cause of coolant loss, change the oil and reset the oil
life system. SeeEngine Oil on page 5-15.
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Engine Fan Noise
If the vehicle has a clutched engine cooling fan, when the
clutch is engaged, the fan spins faster to provide more air
to cool the engine. In most everyday driving conditions,
the fan is spinning slower and the clutch is not fully
engaged. This improves fuel economy and reduces fan
noise. Under heavy vehicle loading, trailer towing, and/or
high outside temperatures, the fan speed increases as
the clutch more fully engages, so you may hear an
increase in fan noise. This is normal and should not be
mistaken as the transmission slipping or making extra
shifts. It is merely the cooling system functioning properly.
The fan will slow down when additional cooling is not
required and the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If the vehicle has electric cooling fans, you may hear the
fans spinning at low speed during most everyday driving.
The fans may turn off if no cooling is required. Under
heavy vehicle loading, trailer towing, and/or high outside
temperatures, or if you are operating the air conditioning
system, the fans may change to high speed and you
may hear an increase in fan noise. This is normal and
indicates that the cooling system is functioning properly.
The fans will change to low speed when additional
cooling is no longer required.
Power Steering Fluid
If the vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
SeeEngine Compartment
Overview on page 5-14for
reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering uid
unless you suspect there is a leak in the system or
you hear an unusual noise. A uid loss in this system
could indicate a problem. Have the system inspected
and repaired.
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How to Check Power Steering Fluid
To check the power steering uid:
1. Turn the key off and let the engine compartment
cool down.
2. Wipe the cap and the top of the reservoir clean.
3. Unscrew the cap and wipe the dipstick with a
clean rag.
4. Replace the cap and completely tighten it.
5. Remove the cap again and look at the uid level on
the dipstick.
The level should be at the FULL COLD mark. If
necessary, add only enough uid to bring the level up to
the mark.
What to Use
To determine what kind of uid to use, see
Recommended Fluids and Lubricants on page 6-13.
Always use the proper uid.
Notice:Use of the incorrect uid may damage the
vehicle and the damages may not be covered by
the vehicle’s warranty. Always use the correct uid
listed inRecommended Fluids and Lubricants
on page 6-13.
Windshield Washer Fluid
What to Use
When windshield washer uid needs to be added, be
sure to read the manufacturer’s instructions before use.
Use a uid that has sufficient protection against
freezing in an area where the temperature may fall
below freezing.
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Adding Washer Fluid
The vehicle has a low washer uid message in the DIC
that comes on when the washer uid is low. The
message is displayed for 15 seconds at the start of
each ignition cycle. When the WASHER FLUID LOW
ADD FLUID message displays, you will need to
add washer uid to the windshield washer uid reservoir.
Open the cap with the
washer symbol on it.
Add washer uid until the
tank is full. SeeEngine
Compartment Overview on
page 5-14for reservoir
location.Notice:When using concentrated washer uid, follow
the manufacturer’s instructions for adding
water.
Do not mix water with ready-to-use washer uid.
Water can cause the solution to freeze and
damage your washer uid tank and other parts
of the washer system. Also, water does not
clean as well as washer uid.
Fill the washer uid tank only three-quarters full
when it is very cold. This allows for uid
expansion if freezing occurs, which could
damage the tank if it is completely full.
Do not use engine coolant (antifreeze) in your
windshield washer. It can damage the vehicle’s
windshield washer system and paint.
5-40

Brakes
Brake Fluid
The brake master cylinder
reservoir is lled with
DOT-3 brake uid. See
Engine Compartment
Overview on page 5-14
for the location of the
reservoir.
There are only two reasons why the brake uid level in
the reservoir might go down:
The brake uid level goes down because of normal
brake lining wear. When new linings are installed,
the uid level goes back up.
A uid leak in the brake hydraulic system can also
cause a low uid level. Have the brake hydraulic
system xed, since a leak means that sooner
or later the brakes will not work well.Do not top off the brake uid. Adding uid does not
correct a leak. If uid is added when the linings
are worn, there will be too much uid when new brake
linings are installed. Add or remove brake uid, as
necessary, only when work is done on the brake
hydraulic system.
{CAUTION:
If too much brake uid is added, it can spill on the
engine and burn, if the engine is hot enough. You
or others could be burned, and the vehicle could
be damaged. Add brake uid only when work is
done on the brake hydraulic system. See
“Checking Brake Fluid” in this section.
When the brake uid falls to a low level, the brake
warning light comes on. SeeBrake System Warning
Light on page 3-40.
Refer to the Maintenance Schedule to determine when
to check the brake uid. SeeScheduled Maintenance
on page 6-4.
5-41

Checking Brake Fluid
Check brake uid by looking at the brake uid reservoir.
SeeEngine Compartment Overview on page 5-14.
The uid level should be
above MIN. If it is not,
have the brake hydraulic
system checked to
see if there is a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.
What to Add
Use only new DOT-3 brake uid from a sealed container.
SeeRecommended Fluids and Lubricants on page 6-13.
Always clean the brake uid reservoir cap and the area
around the cap before removing it. This helps keep
dirt from entering the reservoir.
{CAUTION:
With the wrong kind of uid in the brake hydraulic
system, the brakes might not work well. This could
cause a crash. Always use the proper brake uid.
Notice:
Using the wrong uid can badly damage brake
hydraulic system parts. For example, just a
few drops of mineral-based oil, such as engine
oil, in the brake hydraulic system can damage
brake hydraulic system parts so badly that they
will have to be replaced. Do not let someone
put in the wrong kind of uid.
If brake uid is spilled on the vehicle’s painted
surfaces, the paint nish can be damaged. Be
careful not to spill brake uid on the vehicle.
If you do, wash it off immediately. SeeWashing
Your Vehicle on page 5-111.
5-42