2004 GMC YUKON XL DENALI coolant level

To avoid blowing cold air in cold weather, the
system will delay turning on the fan until warm air is
available. The length of delay depends on the
engine coolant temperature. Pressing the fan switch
will override this delay and change the fan to a
selected speed.
9(Off):Press this button to turn off the entire climate
control system. Outside air will still enter the vehicle,
and will be directed to the ¯oor. This direction can
be changed by pressing the mode button. The
temperature can also be adjusted using either
temperature knob. Press the up or down arrows on the
fan switch, the defrost button, the AUTO button, or
the air conditioning button to turn the system on when it
is off.
Manual Operation
You may manually adjust the air delivery mode or fan
speed.
w9x(Fan):The switch with the fan symbol allows
you to manually adjust the fan speed. Press the up
arrow to increase fan speed and the down arrow
to decrease fan speed.
Pressing this button when the system is off will turn the
system on.
C(Mode):Press this button to manually change the
direction of the air¯ow in your vehicle; keep pressing the
button until the desired mode appears on the display.
If you press the mode button to select an air delivery
mode, the display will change to show you the selected
air mode delivery. The display will then show the
current status of the system. When the system is turned
off, the display will go blank after displaying the
current status of the system.
H(Panel):This setting will deliver air to the
instrument panel outlets.
)(Bi-Level):This setting will deliver warmer air to the
¯oor and cooler air to the instrument panel outlets.
6(Floor):This setting will deliver air to the ¯oor
outlets.
-(Defog):See ªDefogging and Defrostingº later in
this section.
@(Recirculation):Press this button to limit the
amount of outside air entering your vehicle. The light on
the recirculation button will glow. This is helpful when you
are trying to limit odors entering your vehicle and for
maximum air conditioning performance in hot weather.
Press this button again to allow outside air to enter the
vehicle. The light on the recirculation button will go off.
3-22

ENGINE COOLANT HOT
If the cooling system temperature gets hot, this message
will appear in the DIC. Stop the vehicle and let the
engine idle in PARK (P) to allow the coolant to reach a
safe temperature. This message will clear when the
coolant temperature drops to a safe operating
temperature.
ENGINE OVERHEATED
If the engine cooling system reaches unsafe
temperatures for operation, this message will appear in
the DIC and you will hear a chime. Stop and turn off
the vehicle as soon as it is safe to do so to avoid severe
damage. This message will clear when the engine
has cooled to a safe operating temperature.
FUEL LEVEL LOW
If the fuel level is low, this message will appear on the
DIC and you will hear a chime. Refuel as soon as
possible. Pressing the select button will acknowledge
this message immediately and clear it from the DIC
display. It will also clear itself after 10 seconds until the
next ignition cycle. The low fuel light near the fuel
gage will still remain on in either case.
KEYFOB X BATTERY LOW
If a remote keyless entry transmitter battery is low, this
message will appear on the DIC. The battery needs
to be replaced in the transmitter. Pressing the select
button will acknowledge this message and clear it from
the DIC display.
LEFT REAR DOOR AJAR
If the driver's side rear door is not fully closed and the
vehicle is in a drive gear, this message will appear
on the display and you will hear a chime. Stop and turn
off the vehicle, check the door for obstacles, and
close the door again. Check to see if the message still
appears on the DIC. Pressing the select button will
acknowledge this message and clear it from the DIC
display.
LOW COOLANT LEVEL
If your vehicle is equipped with low coolant level sensor,
this message will appear on the DIC if the engine
coolant level is low. Adding coolant will clear the
message.
OIL LIFE RESET
This message will appear on the display for about
10 seconds after resetting the change engine oil
message.
3-59

OIL PRESSURE LOW
If low oil pressure levels occur, this message will be
displayed on the DIC and a chime will sound. Stop the
vehicle as soon as safely possible and do not operate
it until the cause of the low oil pressure has been
corrected. Check your oil as soon as possible and have
your vehicle serviced.
PASSENGER DOOR AJAR
If the passenger's door is not fully closed and the
vehicle is in a drive gear, this message will appear on
the display and you will hear a chime. Stop and turn off
the vehicle, check the door for obstacles, and close
the door again. Check to see if the message still
appears on the DIC. Pressing the select button will
acknowledge this message and clear it from the DIC
display.
RIGHT REAR DOOR AJAR
If the passenger's side rear door is not fully closed and
the vehicle is in a drive gear, this message will
appear on the display and you will hear a chime. Stop
and turn off the vehicle, check the door for obstacles,
and close the door again. Check to see if the message
still appears on the DIC. Pressing the select button
will acknowledge this message and clear it from the DIC
display.
REAR ACCESS OPEN
If the liftgate is open while the ignition is in RUN, this
message will appear on the DIC and you will hear
a chime. Turn off the vehicle and check the liftgate.
Restart the vehicle and check for the message on the
DIC display. Pressing the select button will acknowledge
this message and clear it from the DIC display.
REDUCED ENGINE POWER
This message is displayed and you will hear a chime
when the cooling system temperature gets too hot and
the engine further enters the engine coolant
protection mode.
See
Engine Overheating on page 5-25for further
information.
REPLACE LIFTGATE FUSE
This message will be displayed if the liftgate lock
malfunctions and/or the liftgate fuse blows. For more
information on fuses, see
Fuses and Circuit Breakers on
page 5-103
If the message returns after replacing the fuse, see you
dealer for service.
3-60

Driving On Grades
Reduce speed and shift to a lower gearbeforeyou start
down a long or steep downgrade. If you don't shift
down, you might have to use your brakes so much that
they would get hot and no longer work well.
You can tow in DRIVE (D). You may want to shift the
transmission to THIRD (3) or, if necessary, a lower gear
selection if the transmission shifts too often (e.g.,
under heavy loads and/or hilly conditions).
You may also want to activate the tow/haul mode if the
transmission shifts too often. See ªTow/Haul Modeº
under
Towing a Trailer on page 4-51.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes. If you turn your
engine off immediately after towing at high altitude
on steep uphill grades, your vehicle may show signs
similar to engine overheating. To avoid this, let the
engine run while parked (preferably on level ground)
with the automatic transmission in PARK (P) for a
few minutes before turning the engine off. If you do get
the overheat warning, see
Engine Overheating on
page 5-25.
Parking on Hills
{CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.
But if you ever have to park your rig on a hill, here's
how to do it:
1. Apply your regular brakes, but don't shift into
PARK (P) yet.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake and shift into PARK (P).
5. Release the regular brakes.
4-60

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-18.
B. Coolant Surge Tank. See
Engine Coolant on
page 5-23.
C. Air Filter Restriction Indicator. See
Engine Air
Cleaner/Filter on page 5-18.
D. Engine Oil Dipstick. See
Engine Oil on page 5-13.
E. Engine Oil Fill. See
Engine Oil on page 5-13.
F. Automatic Transmission Dipstick. See
Automatic
Transmission Fluid on page 5-20.
G. Fan. See
Cooling System on page 5-28.
H. Remote Negative (-) Terminal (GND). See
Jump
Starting on page 5-40.
I. Remote Positive (+) Terminal. See
Jump Starting on
page 5-40.
J. Power Steering Fluid Reservoir (Out of View). See
Power Steering Fluid on page 5-34.
K. Brake Master Cylinder Reservoir. See
Brakes on
page 5-36.
L. Underhood Fuse Block. See
Fuses and Circuit
Breakers on page 5-103.
M. Battery. See
Battery on page 5-39.
N. Windshield Washer Fluid Reservoir. See
Windshield
Washer Fluid on page 5-35.
Before closing the hood, be sure all ®ller caps are on
properly. Pull down the hood and close it ®rmly.
Engine Oil
If the CHECK OIL LEVEL message appears on the
instrument cluster, it means you need to check
your engine oil level right away.
For more information, see ªCHECK OIL LEVELº under
DIC Warnings and Messages on page 3-57.
You should check your engine oil level regularly; this is
an added reminder.
Checking Engine Oil
It is a good idea to check your engine oil every time you
get fuel. In order to get an accurate reading, the oil
must be warm and the vehicle must be on level ground.
The engine oil dipstick handle is a yellow loop. See
Engine Compartment Overview on page 5-12for
the location of the engine oil dipstick.
Turn off the engine and give the oil several minutes to
drain back into the oil pan. If you don't, the oil
dipstick might not show the actual level.
Pull out the dipstick and clean it with a paper towel or
cloth, then push it back in all the way. Remove it again,
keeping the tip down, and check the level.
5-13

If you have to add coolant more than four times a year,
have your dealer check your cooling system.
Notice:If you use the proper coolant, you do not
have to add extra inhibitors or additives which claim
to improve the system. These can be harmful.
Checking Coolant
The coolant surge tank is
located in the engine
compartment on the
passenger's side of the
vehicle.
See
Engine Compartment Overview on page 5-12for
more information on location.
{CAUTION:
Turning the surge tank pressure cap when the
engine and radiator are hot can allow steam
and scalding liquids to blow out and burn you
badly. Never turn the surge tank pressure
cap Ð even a little Ð when the engine and
radiator are hot.
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at the FULL
COLD mark.
If your vehicle is equipped with the LOW COOLANT
LEVEL message and it comes on and stays on, it means
you're low on engine coolant.
See ªLow Coolant Levelº under
DIC Warnings and
Messages on page 3-57.
5-24

Cooling System
When you decide it's safe to lift the hood, here's what
you'll see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine FanIf the coolant inside the coolant surge tank is boiling,
don't do anything else until it cools down. The vehicle
should be parked on a level surface.
The coolant level should
be at or above the FULL
COLD mark. If it isn't,
you may have a leak at the
pressure cap or in the
radiator hoses, heater
hoses, radiator, water
pump or somewhere else
in the cooling system.
5-28

How to Add Coolant to the Coolant
Surge Tank
If you haven't found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level isn't at or above the FULL
COLD mark, add a 50/50 mixture of
clean, drinkable
waterand DEX-COOLžcoolant at the coolant
surge tank, but be sure the cooling system, including
the coolant surge tank pressure cap, is cool before you
do it. See
Engine Coolant on page 5-23for more
information.
If no coolant is visible in the surge tank, add coolant
as follows:
{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 radiator
pressure cap Ð even a little Ð they can come
out at high speed. Never turn the cap when the
cooling system, including the radiator pressure
cap, is hot. Wait for the cooling system and
radiator pressure cap to cool if you ever have
to turn the pressure cap.
5-30