2009 HUMMER H2 heater

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

If you get the ENGINE COOLANT HOT message with
no sign of steam, try this for a minute or so:
1. Turn on the heater to full hot at the highest fan
speed and open the windows as necessary.
2. If you are in a traffic jam, shift to N (Neutral);
otherwise, shift to the highest gear while
driving—D(Drive).
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not come back on, you can drive
normally.
If the warning continues and you have not stopped, pull
over, stop, and park the vehicle right away.
If there is still no sign of steam, push down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you are parked. If you still have the warning, turn off the
engine and get everyone out of the vehicle until it
cools down. Also, see “Overheated Engine Protection
Operating Mode” later in this section.
You may decide not to lift the hood but to get service
help right away.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.
5-35

Electrical System (cont.)
Power Windows and Other Power Options....5-110
Underhood Fuse Block...............................5-113
Windshield Wiper Fuses.............................5-110
Electronic Immobilizer
PASS-Key
®III+...........................................2-25
Electronic Immobilizer Operation
PASS-Key
®III+...........................................2-26
Electronically Controlled Air Suspension System . . . 4-53
Engine
Air Cleaner/Filter.........................................5-20
Check and Service Engine Soon Lamp...........3-40
Coolant......................................................5-31
Coolant Heater............................................2-31
Coolant Temperature Gage...........................3-39
Drive Belt Routing.......................................6-16
Engine Compartment Overview......................5-14
Exhaust.....................................................2-45
Oil .............................................................5-15
Oil Life System...........................................5-18
Overheated Protection Operating Mode...........5-35
Overheating................................................5-33
Starting......................................................2-29
Entry/Exit Lighting...........................................3-18
Event Data Recorders.....................................7-17
Extender, Safety Belt.......................................1-39
Exterior Lamps...............................................3-15
F
Filter
Engine Air Cleaner......................................5-20
Finish Damage.............................................5-108
First Aid Kit....................................................4-42
Fixed Mast Antenna.......................................3-130
Flashers, Hazard Warning.................................. 3-6
Flash-to-Pass................................................... 3-9
Flat Tire........................................................5-79
Flat Tire, Changing.........................................5-80
Flat Tire, Storing.....................................5-95, 5-98
Fluid
Automatic Transmission................................5-23
Power Steering...........................................5-36
Windshield Washer......................................5-37
Folding Rear Seat...........................................1-11
Four-Wheel Drive............................................5-48
Four-Wheel Drive, Full-Time.............................2-37
Front Axle......................................................5-49
Front Mounted Receiver...................................4-43
Fuel............................................................... 5-5
Additives...................................................... 5-6
California Fuel.............................................. 5-6
Driving for Better Economy............................. 4-2
E85 (85% Ethanol)........................................ 5-7
Filling a Portable Fuel Container....................5-10
5

Fuel (cont.)
Filling the Tank............................................. 5-8
Fuels in Foreign Countries.............................. 5-8
Gage .........................................................3-45
Gasoline Octane........................................... 5-5
Gasoline Specications.................................. 5-5
Low Warning Light.......................................3-46
Fuses
Center Instrument Panel Fuse Block.............5-112
Fuses and Circuit Breakers.........................5-110
Instrument Panel Fuse Block.......................5-111
Underhood Fuse Block...............................5-113
Windshield Wiper.......................................5-110
G
Gage
Engine Coolant Temperature.........................3-39
Fuel..........................................................3-45
Oil Pressure...............................................3-42
Speedometer..............................................3-31
Tachometer.................................................3-31
Voltmeter Gage...........................................3-36
Garage Door Opener.......................................2-57
Gasoline
Octane........................................................ 5-5
Specications............................................... 5-5
Glove Box.....................................................2-64
GM Mobility Reimbursement Program.................. 7-7
H
Hazard Warning Flashers................................... 3-6
Head Restraints............................................... 1-2
Headlamps....................................................5-51
Bulb Replacement.......................................5-50
Daytime Running Lamp........................3-16, 5-52
Exterior Lamps............................................3-15
Flash-to-Pass............................................... 3-9
Front Turn Signal and Parking Lamps.............5-52
Halogen Bulbs............................................5-50
High/Low Beam Changer................................ 3-9
On Reminder..............................................3-16
Roof Marker Lamps.....................................5-53
Heated Seats................................................... 1-6
Heated Steering Wheel..................................... 3-7
Heater
Engine Coolant...........................................2-31
Heater...........................................................3-22
Highbeam On Light.........................................3-44
Highway Hypnosis...........................................4-35
Hill and Mountain Roads..................................4-36
Hood
Checking Things Under................................5-11
Release.....................................................5-12
Horn ............................................................... 3-6
How to Wear Safety Belts Properly...................1-25
6