2003 GMC SIERRA DENALI radiator

See Driver Information Center (DIC) on page 3-43 for
further information.
If the transmission fluid reaches temperatures of
approximately 275°F
(1 35°C) or greater, the Driver
Information Center wiil display a
TRANS HOT IDLE
ENG warning message. 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 (1 27°C). If the transmission continues to operate
above
265°F (13O"C), contact your nearest dealer or
the
GM Roadside Assistance Center. See Roadside
Assistance Program
on page 7-5.
Notices 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
0 Hot outside air temperatures
0 Hauling a large or heavy load
0 Low transmission fluid level
High transmission fluid level
0 Restricted air flow to the radiator and the auxiliary
transmission oil cooler
(if equipped).
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.
3-37

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.
Nofice: 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
0 Hauling a large or heavy load
Low transmission fluid level
High transmission fluid level
transmission oil cooler.
0 Restricted air flow to the radiator and the auxiliary
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.
3-59

Engine Coolant
The cooling system in your vehicle is filled with
DEX-COOL@ engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240
000 km), whichever occurs first, if you add only
DEX-COOL@ extended life coolant.
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
5-27.
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.
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.
Let the warning lights and gages work as they
should.
5-24

What to Use
Use a mixture of one-half dean, drinkable water and
one-half
DEX-COOL@ coolant which won’t damage
aluminum parts.
If you use this coolant mixture,
vou don’t need
to add anvthing else.
I
Addir - mi- -)lain water to lr cooling s- tem
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: 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.
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.
5-25

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
5-12 for more ’
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
- 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 3-53.
Adding Coolant
If you need more coolant, add the proper DEX-COOL@
coolant mixture
at the surge tank, but only when the
engine is cool.
I
You can I: burned if you spill coolant on hot
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.
I I
When replacing the pressure cap, make sure it is
hand-tight.
5-26

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 The coolant level should
be at
or above the FULL
COLD mark. If it isn't,
you may have a leak at the
rn*:A.~~ z,=7j_ . %%A" %!!:..- pressure cap or in the
*^" radiator hoses, heater
hoses, radiator, water
pump or somewhere else
in the cooling system.
I
5-30

I
Heater and radiator 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.
5-31

Adding ~.ly p.-.n water to your coa....g 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 i i 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.
I
You can be burned if you spill coolant on hot
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.
5-33