2008 HUMMER H2 Owners Manual

Notice:The engine is designed to work with the
electronics in your vehicle. If you add electrical
parts or accessories, you could change the way the
engine operates. Before adding electrical equipment,
check with your dealer/retailer. If you do not, your
engine might not perform properly. Any resulting
damage would not be covered by your vehicle’s
warranty.
Engine Coolant Heater
The engine coolant heater, if available, can help in cold
weather conditions at or below 0°F (−18°C) for easier
starting and better fuel economy during engine warm-up.
Plug in the coolant heater at least four hours before
starting your vehicle. An internal thermostat in the
plug-end of the cord may exist which will prevent
engine coolant heater operation at temperatures
above 0°F (−18°C).
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Locate the electrical cord near the front recovery
loop on the driver’s side of the vehicle.
3. Plug it into a normal, grounded 110-volt AC outlet.
{CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the
wrong kind of extension cord could overheat
and cause a re. You could be seriously
injured. Plug the cord into a properly grounded
three-prong 110-volt AC outlet. If the cord will
not reach, use a heavy-duty three-prong
extension cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug and
store the cord as it was before to keep it away
from moving engine parts. If you do not, it could be
damaged.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead
of trying to list everything here, we ask that you contact
your dealer/retailer in the area where you will be
parking your vehicle. The dealer/retailer can give you
the best advice for that particular area.
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Automatic Transmission Operation
Your vehicle has a Hydra-Matic®6L80 automatic
transmission, and has an electronic shift position
indicator within the instrument panel cluster. This display
comes on when the ignition key is turned to the
ON/RUN position.
There are several different positions for the shift lever.
PARK (P):This position locks the rear wheels. It is the
best position to use when you start your engine
because your vehicle cannot move easily.
When parked on a hill, especially when the vehicle
has a heavy load, you may notice an increase in the
effort to shift out of PARK (P). See Torque Lock
(Automatic Transmission) underShifting Into PARK (P)
on page 2-41for more information.{CAUTION:
It is dangerous to get out of your vehicle if the
shift lever is not fully in PARK (P) with the
parking brake rmly set. Your vehicle can roll.
Do not leave your vehicle when the engine is
running unless you have to. If you have left
the engine running, the vehicle can move
suddenly. You or others could be injured.
To be sure your vehicle will not move, even
when you are on fairly level ground, always set
your parking brake and move the shift lever
to PARK (P). SeeShifting Into PARK (P) on
page 2-41. If you are pulling a trailer, see
Towing a Trailer on page 4-55.
REVERSE (R):Use this gear to back up.
Notice:Shifting to REVERSE (R) while your vehicle
is moving forward could damage the transmission.
The repairs would not be covered by your warranty.
Shift to REVERSE (R) only after your vehicle is
stopped.
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To rock your vehicle back and forth to get out of snow,
ice, or sand without damaging the transmission, see
If Your Vehicle is Stuck in Sand, Mud, Ice, or Snow on
page 4-39.
NEUTRAL (N):In this position, the engine does not
connect with the wheels. To restart when you are
already moving, use NEUTRAL (N) only. Also, use
NEUTRAL (N) when your vehicle is being towed.
{CAUTION:
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless
your foot is rmly on the brake pedal, your
vehicle could move very rapidly. You could
lose control and hit people or objects. Do not
shift into a drive gear while your engine is
running at high speed.
Notice:Shifting out of PARK (P) or NEUTRAL (N)
with the engine running at high speed may damage
the transmission. The repairs would not be covered
by your warranty. Be sure the engine is not running
at high speed when shifting your vehicle.DRIVE (D):This position is for normal driving. It
provides the best fuel economy for your vehicle. If you
need more power for passing, and you are:
Going less than about 35 mph (55 km/h), push the
accelerator pedal about halfway down.
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
By doing this, the vehicle shifts down to the next gear
and has more power.
DRIVE (D) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road
driving. You may want to shift the transmission to a
lower gear selection if the transmission shifts too often.
Downshifting the transmission in slippery road
conditions could result in skidding, see Skidding under
Loss of Control on page 4-12.
MANUAL MODE (M):This position lets drivers select
the range of gears appropriate for current driving
conditions. If your vehicle has this feature, see Driver
Shift Control (DSC) later in this section.
Notice:Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator pedal
may damage the transmission. The repair will not be
covered by your warranty. If you are stuck, do not
spin the tires. When stopping on a hill, use the brakes
to hold the vehicle in place.
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SECOND (2):This position reduces vehicle speed
without using the brakes. Use SECOND (2) on hills.
It can help control your speed as you go down steep
mountain roads, but then you may also want to use the
brakes off and on.
FIRST (1):This position reduces vehicle speed without
using the brakes. Use it for major/severe downgrades
and off-road driving where the vehicle would otherwise
accelerate due to steepness of grade.
When you shift to SECOND (2) or FIRST (1) it provides
the lowest gear appropriate to your current road
speed and continues to downshift as the vehicle slows,
eventually downshifting to the selected gear.
Your vehicle has a shift stabilization feature that
adjusts the transmission shifting to the current driving
conditions in order to reduce rapid upshifts and
downshifts. This shift stabilization feature is designed to
determine, before making an upshift, if the engine
will be able to maintain vehicle speed by analyzing
things such as vehicle speed, throttle position andvehicle load. If the shift stabilization feature determines
that a current vehicle speed cannot be maintained,
the transmission does not upshift and instead holds the
current gear. In some cases, this may appear to be
a delayed shift, however the transmission is operating
normally.
Your vehicle’s transmission uses adaptive shift controls
that compares key shift parameters to pre-programmed
ideal shifts stored in the transmissions computer.
The transmission constantly makes adjustments to
improve vehicle performance according to how
the vehicle is being used, such as with a heavy load or
when temperature changes. During this adaptive
shift controls process, shifting may feel different as the
transmission determines the best settings.
When temperatures are very cold, the Hydra-Matic
®
6L80 automatic transmission’s gear shifting may
be delayed providing more stable shifts until the engine
warms up. Shifts may be more noticeable with a cold
transmission. This difference in shifting is normal.
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Driver Shift Control (DSC)
Your vehicle has a Driver
Shift Control (DSC).
The DSC controls the
vehicle’s transmission
and vehicle speed while
driving down hill or towing
a trailer by allowing you
to select a desired range
of gears.
To use this feature:
1. Move the shift lever to the MANUAL MODE (M).
This will force a downshift from the current gear,
for gears 3 through 6.
2. Press the (+) plus or (−) minus button on the left
side of the steering wheel, to select the desired
range of gears for your current driving conditions.When in the MANUAL MODE (M) a number will display
next to the M, indicating the maximum available
gear. The DIC display will show the message MANUAL
SHIFT on the rst line and the maximum available
gear will be displayed on the second line. SeeDriver
Information Center (DIC) on page 3-49andDIC
Operation and Displays (Using DIC Buttons) on
page 3-49orDIC Operation and Displays (Using Trip
Odometer Reset Stem) on page 3-54for more
information. The number displayed in the DIC is the
highest gear available. The transmission will be limited
to the gear selected and lower gears. Shifting will
occur normally while driving, however the cluster will
continue to display the maximum available gear.
Higher gears will not be available unless the selection
is changed to include higher gears using the (+) plus
button.
Grade Braking is not available when the Driver Shift
Control is active. SeeTow/Haul Mode on page 2-36and
Towing a Trailer on page 4-55for more information.
While using the DSC, cruise control and the tow/haul
mode can be used.
2-35

Tow/Haul Mode
Your vehicle is equipped
with a tow/haul mode.
The button is located on
the instrument panel
to the right of the
steering wheel.
You can use this feature to assist when towing or
hauling a heavy load. See “Tow/Haul Mode” under
Towing a Trailer on page 4-55for more information.
Full-Time Four-Wheel Drive
The transfer case on your Full-Time Four-Wheel Drive
vehicle is designed to constantly send the engine’s
driving power to all four wheels for extra traction.
To get the most out of Full-Time Four-Wheel Drive,
you must be familiar with its operation.
Notice:Driving on pavement in Four-Wheel
High Lock or Four Wheel Low Lock for extended
periods may cause premature wear on your vehicle’s
powertrain and tires. Do not drive in Four-Wheel
High Lock or Four-Wheel Low Lock on pavement for
extended periods.
Transfer Case Dial
The transfer case dial is
located to the right of the
instrument panel cluster.
Use this switch to shift into
and out of the different
Full-Time Four-Wheel
Drive modes.
The transfer case is a part of the Full-Time Four-Wheel
Drive system and allows the following four different
modes of operation:
4
m(Full-Time Four-Wheel Drive):This setting is used
for driving in most street and highway situations.
It can be used for light or variable off-road conditions.
4
mQ(Four-Wheel-High Lock):Use this mode when
you need extra traction in most off-road situations
such as sand, mud, snow, or level, rocky trails.
4
nQ(Four-Wheel-Low Lock):This mode delivers
extra torque to all four wheels and is used for extreme
off-road conditions. Choose Four-Wheel-Low Lock while
driving off-road in deep sand, mud, or snow and climbing
or descending steep hills.
2-36

When in this mode you can also choose to lock the rear
axle for additional traction in extreme off-road situations.
SeeLocking Rear Axle on page 4-6.
Notice:Operating your vehicle in
Four-Wheel-Low Lock above 50 mph (80 km/h) for
any extended period of time could cause damage to
the transfer case. Do not operate your vehicle in
Four-Wheel-Low Lock above 50 mph (80 km/h)
for extended periods.
{CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the
transmission is in PARK (P). You or someone
else could be seriously injured. Be sure to set
the parking brake before placing the transfer
case in NEUTRAL. SeeParking Brake on
page 2-40.N (NEUTRAL):Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 4-51orTowing
Your Vehicle on page 4-51for more information.
Indicator lights in the dial shows which mode you are in.
The indicator lights will come on briey when you turn
on the ignition and one will stay on. If the lights do
not come on, take your vehicle to your dealer/retailer
for service. An indicator light will ash while shifting
the transfer case. It will remain on when the shift
is complete. If for some reason the transfer case
cannot make a requested shift, it will return to the last
chosen setting.
If the SERVICE 4WD message stays on, you should
take your vehicle to your dealer/retailer for service.
See “Service 4WD message” underDriver Information
Center (DIC) on page 3-49.
2-37

Shifting between Four-Wheel High and
Four-Wheel-High Lock
With the vehicle traveling less than 40 mph
(64 km/h), turn the dial to the Four-Wheel High or
Four-Wheel-High Lock position. The indicator light on
the dial will ash while shifting. It will remain on
when the shift is complete.
It may be necessary to drive backwards for a short
distance of 25 feet (7.5 m) to get the lock feature
to disengage.
Shifting into Four-Wheel-Low Lock
To shift into Four-Wheel-Low Lock, the ignition must be
in RUN and the vehicle must be stopped or moving
less than 3 mph (5 km/h) with the transmission in
NEUTRAL (N). The preferred method for shifting into
Four-Wheel Low is to have your vehicle moving
1 to 2 mph (1.6 to 3.2 km/h). Turn the dial to the
Four-Wheel-Low Lock position. You must wait for the
Four-Wheel-Low Lock indicator light on the dial to
stop ashing and remain lit before shifting the
transmission in gear.When the transfer case is shifted into Four-Wheel-Low
Lock position a StabiliTrak
®indicator light will come
on to show that the system has been turned off and a
message will show in the DIC. SeeDIC Warnings
and Messages on page 3-56for more information.
Notice:Shifting the transmission into gear before
the indicator light stops ashing could cause
damage to the transfer case. Always wait until the
indicator light stops ashing before putting the
transmission back in gear.
It is normal for your vehicle to have engagement noise
and bump when shifting between Four-Wheel Low
and Four-Wheel High or Four-Wheel-High Lock ranges
or from NEUTRAL with the engine running.
If the Four-Wheel-Low Lock position is selected when
your vehicle is in gear and/or moving, the Four-Wheel
Low Lock indicator light will ash for 15 seconds and not
complete the shift unless your vehicle is moving less
than 3 mph (5 km/h) and the transmission is in
NEUTRAL (N). After 15 seconds the transfer case will
return to the setting last chosen.
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