2003 GMC YUKON DENALI radiator

Transmission Temperature Gage
--
United States Canada
Your vehicle is equipped with a transmission
temperature gage.
When your ignition is on, the gage shows the
temperature of the transmission fluid. The normal
operating range is from
100°F (38°C) to about 265°F
(1 30°C).
At approximately 265°F (130°C), the DIC will display a
TRANSMISSION HOT message and the transmission
will enter a transmission protection mode. When
the transmission enters the protection mode, you may
notice a change in the transmission shifting patterns.
The transmission will return to normal shifting patterns
when the transmission fluid temperature falls below
260°F
(1 27°C). See
Driver Information
Center (DIC) on page 3-43 for
further information.
If the transmission fluid reaches temperatures of
approximately 275°F (135°C) or greater, the DIC will
display a TRANS
HOT tDLE ENGtNE warning message
and a chime will sound. Pull the vehicle
off the
roadway when it is safe
to do so. Set the parking brake,
place the transmission in PARK
(P) and allow the
engine to idle until the transmission temperature falls
below 260°F (127°C).
If the transmission continues
to operate above 265°F
(1 30"C), please contact your
nearest dealer or the
GM Roadside Assistance Center.
Notice: If you keep driving your vehicle with the
transmission temperature gage above the normal
operating range, you can damage the transmission.
This could lead to costly repairs that may not be
covered under your warranty.
The following situations can cause the transmission to
operate at higher temperatures:
0 Towing a trailer,
* hot outside air temperatures,
0 hauling a large or heavy load,
low transmission fluid level,
high transmission fluid level,
0 restricted air flow to the radiator.

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.
CHECK WASHER FLUID
If the washer fluid level is low, this message will appear
on the DIC. Adding washer fluid will clear the message.
Pressing the select button will acknowledge this
message and clear it from the DIC display. This
message will clear itself after
10 seconds until the next
igntion cycle.
TRANSMISSION HOT
If the transmission fluid temperature becomes high, the
message center will display this message.
When the transmission enters the protection mode, you
may notice a change in the transmission shifting
patterns. When the transmission fluid temperature
returns
to normal, the display will turn off and the
transmission shifting patterns will return
to normal.
Notice: If you keep driving your vehicle with the
transmission
TRANS FLUID HOT message
displayed, you can damage the transmission. This
could lead to costly repairs that may not be covered
under your warranty.
The following situations can cause the transmission to
operate at higher temperatures:
Towing a trailer
@ Hot outside air temperatures
Hauling a large or heavy load
Low transmission fluid level
High transmission fluid level
Restricted air flow to the radiator.
A temporary solution
to hotter transmission operating
temperatures may be
to let the transmission cool down.
If the transmission is operated at higher temperatures
on a frequent basis, see Scheduled Maintenance
on page 6-5 for the proper transmission maintenance
intervals.
TRANS HOT IDLE ENGINE
If the transmission fluid in the vehicle gets hot, this
message will appear on the DIC along with a continuous
chime. Driving with the transmission fluid temperature
high can cause damage
to the vehicle.
3-55

The following explains your cooling system and how to
add coolant when it is low. If you have a problem
with engine overheating, see Engine Overheating
on
page 5-25.
A 50/50 mixture of clean, drinkable water and
DEX-COOL@ coolant will:
Give freezing protection down to -34°F (-37°C).
Give boiling protection up to 265°F (129°C).
Protect against rust and corrosion.
Help keep the proper engine temperature.
e Let the warning lights and gages work as they
should.
Notice: When adding coolant, it is important that
you use only
DEX-COOL@ (silicate-free) coolant.
If coolant other than DEX-COOL@ is added to the
system, premature engine, heater core or radiator
corrosion may result. In addition, the engine coolant
will require change sooner
-- at 30,000 miles
(50,000 km) or 24 months, whichever occurs first.
Damage caused by the use of coolant other than
DEX-COQL.@ is not covered by your new vehicle
warranty.
What to Use
Use a mixture of one-half clean, drinkable water and
one-half DEX-COOL@ coolant which won’t damage
aluminum parts.
!f YOU uss this coolant mixture,
you don’t need
to add anything else.
Adding c..ly
c water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can boil before the proper coolant mixture will. Your
vehicle’s coolant warning system
is set for the
proper coolant mixture. With plain water or the
wrong mixture, your engine could get too hot
but you wouldn’t get the overheat warning.
Your engine could catch fire and you or others
could be burned. Use a
50/50 mixture of clean,
drinkable water and DEX-COQL@ coolant.
Notice: If you use an improper coolant mixture,
your engine could overheat and be badly damaged.
The repair cost wouldn’t be covered by your
warranty. Too much water
in the mixture can freeze
and crack the engine, radiator, heater core and
other parts.
5-23

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 don’t
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.
.
1 ~ ---lg the surge tanl- ,xessure 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
- even a little - 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 the LOW COOLANT
LEVEL message comes on and
stays on, it means you’re low on engine coolant.
See “Low Coolant Level” under
DIC Warnings and
Messages on page
3-52.
See Engine Compartment Overview on page 5-12 for
more information on location.
5-24

Cooling System
When you decide it’s safe to lift the hood, here’s what
you’ll see: If 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.
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Fan
1
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

Heater and rac.-:or hoses, and other engine
parts, can be very hot. Don’t touch them. If you
do, you can be burned.
Don’t run the engine
if there is a leak. If you
run
the engine, it could lose all coolant. That
could cause an engine fire, and you could be
burned. Get any leak fixed before you drive the
vehicle.
If there seems to be no leak, start the engine again.
The engine cooling fan speed should increase when idle
speed is doubled by pushing the accelerator pedal
down. If it doesn’t, your vehicle needs service. Turn
off
the engine.
Notice: Engine damage from running your engine
without coolant isn’t covered by your warranty.
See “Overheated Engine Protection Operating
Mode”
in the Index for information on driving to a
safe place
in an emergency.
Notice: When adding coolant, it is important that
you use only
DEX-COOL@ (silicate-free) coolant.
If coolant other than DEX-COOL@ is added to
the system, premature engine, heater core or radiator corrosion
may result. In addition, the engine
coolant will require change sooner
- at 30,000 miles
(50 000 km) or 24 months, whichever occurs first.
Damage caused by
the use of coolant other
than DEX-COOL@ is not covered by your new vehicle
warranty.
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
water and
DEX-COOL@ coolant 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 5-22 for more
information.
If no coolant is visible in the surge tank, add coolant as
follows:
5-29

Steam and scalding liquids f I hl cooling
system can blow out
and burn you badly. They
are under pressure,
and if you turn the radiator
pressure cap
-- even a little -- 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

Adding only plain water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can boil
before the proper coolant mixture will. Your
vehicle's coolant warning system
is set for the
proper coolant mixture.
With plain water or the
wrong mixture, your engine could get too hot
but you wouldn't get the overheat warning.
Your engine could catch fire and you or others
could be burned. Use a
50/50 mixture of clean,
drinkable water and DEX
COOL@ coolant.
Notice: In cold weather, water can freeze and crack
the engine, radiator, heater core and other parts.
Use the recommended coolant and the proper
coolant mixture. You can be burned
if you spill coolant on tist
engine parts. Coolant contains ethylene glycol
and
it will burn if the engine parts are hot
enough. Don't
spill coolant on a hot engine.
1. Park the vehicle on a
level surface.
SURGE RESERVOIR
15 PSI
TANK - 105 kPa
D'EXPANSION I
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
(left) about one full turn. If you hear a hiss, wait for
that
to stop. A hiss means there is still some
pressure left.
5-31