cooling HUMMER H2 2009 User Guide

Hill and Mountain Roads
Driving on steep hills or through mountains is different
than driving on at or rolling terrain. Tips for driving
in these conditions include:
Keep the vehicle serviced and in good shape.
Check all uid levels and brakes, tires, cooling
system, and transmission.
Going down steep or long hills, shift to a
lower gear.
{CAUTION:
If you do not shift down, the brakes could get so
hot that they would not work well. You would then
have poor braking or even none going down a hill.
You could crash. Shift down to let the engine
assist the brakes on a steep downhill slope.
{CAUTION:
Coasting downhill in N (Neutral) or with the ignition
off is dangerous. The brakes will have to do all the
work of slowing down and they could get so hot
that they would not work well. You would then
have poor braking or even none going down a hill.
You could crash. Always have the engine running
and the vehicle in gear when going downhill.
Stay in your own lane. Do not swing wide or cut
across the center of the road. Drive at speeds
that let you stay in your own lane.
Top of hills: Be alert — something could be in your
lane (stalled car, accident).
Pay attention to special road signs (falling rocks
area, winding roads, long grades, passing or
no-passing zones) and take appropriate action.
SeeOff-Road Driving on page 4-15for information
about driving off-road.
4-36

Maintenance When Trailer Towing
The vehicle needs service more often when pulling a
trailer. See this manual’s Maintenance Schedule or Index
for more information. Things that are especially important
in trailer operation are automatic transmission uid,
engine oil, axle lubricant, belts, cooling system and brake
system. It is a good idea to inspect these before and
during the trip.
Check periodically to see that all hitch nuts and bolts
are tight.
Trailer Wiring Harness
Heavy-Duty Trailer Wiring Harness
Package
The vehicle is equipped with the seven-wire trailer towing
harness. This harness with a seven-pin universal trailer
connector is attached to a bracket on the hitch platform.The seven-wire harness contains the following trailer
circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Red/Black: Battery Feed*
Dark Blue: Trailer Brake*
*There is a location in the Underhood Fuse Block for
these circuits, but they are not connected. They should
be connected, and proper fuses installed, by your
dealer/retailer or a qualied service center.
If charging a remote (non-vehicle) battery, press the
Tow/Haul mode button located at the end of the
shift lever. This will boost the vehicle system voltage
and properly charge the battery.
4-67

Service............................................................5-3
Accessories and Modications..........................5-3
California Proposition 65 Warning.....................5-4
California Perchlorate Materials Requirements.....5-4
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside of
the Vehicle.................................................5-5
Fuel................................................................5-5
Gasoline Octane............................................5-5
Gasoline Specications....................................5-5
California Fuel...............................................5-6
Additives.......................................................5-6
Fuel E85 (85% Ethanol)..................................5-7
Fuels in Foreign Countries...............................5-8
Filling the Tank..............................................5-8
Filling a Portable Fuel Container.....................5-10
Checking Things Under the Hood....................5-11
Hood Release..............................................5-12
Engine Compartment Overview.......................5-14
Engine Oil...................................................5-15
Engine Oil Life System..................................5-18
Engine Air Cleaner/Filter................................5-20
Automatic Transmission Fluid.........................5-23
Cooling System............................................5-27
Engine Coolant.............................................5-31
Engine Overheating.......................................5-33Overheated Engine Protection
Operating Mode.........................................5-35
Power Steering Fluid.....................................5-36
Windshield Washer Fluid................................5-37
Brakes........................................................5-38
Battery........................................................5-41
Jump Starting...............................................5-42
Rear Axle.......................................................5-47
Four-Wheel Drive............................................5-48
Front Axle......................................................5-49
Bulb Replacement..........................................5-50
Halogen Bulbs..............................................5-50
Headlamps..................................................5-51
Front Turn Signal and Parking Lamps..............5-52
Daytime Running Lamps (DRL).......................5-52
Roof Marker Lamps......................................5-53
Taillamps, Turn Signal, Stoplamps and
Back-up Lamps.........................................5-54
Replacement Bulbs.......................................5-55
Windshield Wiper Blade Replacement..............5-56
Tires..............................................................5-57
Tire Sidewall Labeling...................................5-58
Tire Terminology and Denitions.....................5-60
Ination - Tire Pressure.................................5-63
Tire Pressure Monitor System.........................5-64
Section 5 Service and Appearance Care
5-1

A. Coolant Surge Tank. SeeCooling System on
page 5-27.
B. Engine Air Cleaner/Filter and Air Filter Restriction
Indicator (If Equipped). SeeEngine Air Cleaner/Filter
on page 5-20.
C. Windshield Washer Fluid Reservoir. See “Adding
Washer Fluid” underWindshield Washer Fluid
on page 5-37.
D. Engine Oil Fill Cap. See “When to Add Engine Oil”
underEngine Oil on page 5-15.
E. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil on page 5-15.
F. Air Filter Restriction Indicator (If Equipped).
SeeEngine Air Cleaner/Filter on page 5-20.
G. Automatic Transmission Fluid Dipstick. See
“Checking the Fluid Level” underAutomatic
Transmission Fluid on page 5-23.
H. Engine Cooling Fan. SeeCooling System on
page 5-27.
I. Remote Negative (−) Terminal (GND). SeeJump
Starting on page 5-42.
J. Power Steering Fluid Reservoir (Out of View).
SeePower Steering Fluid on page 5-36.K. Remote Positive (+) Terminal. SeeJump Starting on
page 5-42.
L. Brake Fluid Reservoir. See “Brake Fluid” under
Brakes on page 5-38.
M.Underhood Fuse Block on page 5-113.
N.Battery on page 5-41.
Engine Oil
Checking Engine Oil
It is a good idea to check the engine oil level at each
fuel ll. 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 5-14for
the location of the engine oil dipstick.
1. Turn off the engine and give the oil several minutes
to drain back into the oil pan. If this is not done, the
oil dipstick might not show the actual level.
2. 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.
5-15

Cooling System
When you decide it is safe to lift the hood, here is what
you will see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Cooling Fan{CAUTION:
An electric fan under the hood can start up and
injure you even when the engine is not running.
Keep hands, clothing, and tools away from any
underhood electric fan.
If the coolant inside the coolant surge tank is boiling, do
not do anything else until it cools down. The vehicle
should be parked on a level surface. Check the coolant
level after the system cools down. Some amount of
coolant may be lost due to overheating.
5-27

The coolant level should be at or above the FULL
COLD mark. If it is not, 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.
{CAUTION:
Heater and radiator hoses, and other engine parts,
can be very hot. Do not touch them. If you do, you
can be burned.
Do not run the engine if there is a leak. If you run
the engine, it could lose all coolant. That could
cause an engine re, and you could be burned.
Get any leak xed 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 does not, the vehicle needs service. Turn off the
engine.Notice:Engine damage from running your engine
without coolant is not covered by your warranty. See
Overheated Engine Protection Operating Mode on
page 5-35for information on driving to a safe place
in an emergency.
Notice:Using coolant other than DEX-COOL
®can
cause premature engine, heater core, or radiator
corrosion. In addition, the engine coolant could
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by the vehicle warranty.
Always use DEX-COOL
®(silicate-free) coolant in
the vehicle.
How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level is not 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 5-31for more information.
5-28

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 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.
{CAUTION:
Adding only plain water to the cooling system can
be dangerous. Plain water, or some other liquid
such as alcohol, can boil before the proper coolant
mixture will. The vehicle’s coolant warning system
is set for the proper coolant mixture. With plain
water or the wrong mixture, the engine could get
too hot but you would not get the overheat
warning. The engine could catch re 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.
5-29

{CAUTION:
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. Do
not spill coolant on a hot engine.
1. Locate the coolant
surge tank pressure
cap that has this label.
2. You can remove the coolant surge tank pressure
cap when the cooling system, including the coolant
surge tank pressure cap and upper radiator hose,
are 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.
3. Then keep turning the pressure cap slowly, and
remove it.4. Fill the coolant surge tank with the proper mixture,
to the FULL COLD mark.
5-30

5. 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.
6. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
7. Verify coolant level after engine is shut off and the
coolant is cold. If necessary, repeat coolant ll
procedure steps 1 through 7.
Engine Coolant
The cooling system in the vehicle is lled with
DEX-COOL®engine coolant. This coolant is designed
to remain in the vehicle for ve years or 150,000 miles
(240 000 km), whichever occurs rst, if you add only
DEX-COOL
®extended life coolant.
The following explains the cooling system and how to add
coolant when it is low. If you have a problem with engine
overheating, seeEngine Overheating on page 5-33.
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.
Let the warning lights and gages work as they
should.
Notice:Using coolant other than DEX-COOL
®can
cause premature engine, heater core, or radiator
corrosion. In addition, the engine coolant may
require changing sooner, at the rst maintenance
service after each 30,000 miles (50 000 km) or
24 months, whichever occurs rst. Any repairs would
not be covered by the vehicle warranty. Always use
DEX-COOL
®(silicate-free) coolant in the vehicle.
5-31

What Kind of Coolant to Use
Use a mixture of one-half clean, drinkable water and
one-half DEX-COOL®coolant which will not damage
aluminum parts. If you use this coolant mixture, you do
not need to add anything else.
{CAUTION:
Adding only plain water to the cooling system can
be dangerous. Plain water, or some other liquid
such as alcohol, can boil before the proper coolant
mixture will. The vehicle’s coolant warning system
is set for the proper coolant mixture. With plain
water or the wrong mixture, the engine could get
too hot but would not get the overheat warning.
The engine could catch re and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.Notice:If an improper coolant mixture is used, the
engine could overheat and be badly damaged. The
repair cost would not be covered by the vehicle
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/retailer check the cooling system.
Notice:If extra inhibitors and/or additives are used
in the vehicle’s cooling system, the vehicle could
be damaged. Use only the proper mixture of
the engine coolant listed in this manual for the
cooling system. SeeRecommended Fluids and
Lubricants on page 6-13for more information.
5-32