2009 HUMMER H2 engine

2 (Second):This position reduces vehicle speed
without using the brakes. Use 2 (Second) on hills.
It can help control vehicle speed as you go down steep
mountain roads, but then you may also want to use
the brakes off and on.
1 (First):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 2 (Second) or 1 (First) 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.
The 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 and vehicle 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.
The transmission uses adaptive shift controls that
compares key shift parameters to pre-programmed
ideal shifts stored in the transmission’s 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 the temperature changes. During this adaptive
shift control 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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Tow/Haul Mode
The vehicle has a tow/haul mode. The tow/haul mode
adjusts the transmission shift pattern to reduce shift
cycling, providing increased performance, vehicle
control, and transmission cooling while towing or
hauling heavy loads.
Press the button located on the instrument panel to the
right of the steering wheel to turn tow/haul on or off. While
tow/haul is on, a light on the instrument panel cluster
comes on.
SeeTow/Haul Mode Light on page 3-44for more
information.
Also see “Tow Haul Mode” underTowing a Trailer on
page 4-55for more information.
Grade Braking
Grade Braking is only active while the Tow/Haul Mode is
selected and you are not in the Range Selection Mode.
See “Tow/Haul Mode listed previously andAutomatic
Transmission Operation on page 2-32for more
information on the Range Selection Mode. Grade Braking
assists in maintaining desired vehicle speeds when
driving on downhill grades by automatically implementing
a shift schedule that utilizes the engine and transmission
to slow the vehicle. This reduces wear on the braking
system and increases control of the vehicle. Grade
Braking monitors vehicle speed, acceleration, engine
torque and brake pedal usage. Using this information,
it detects when the truck is on a downhill grade and the
driver desires to slow the vehicle by pressing the brake.
Also seeTowing a Trailer on page 4-55for more
information.
2-36

Cruise Grade Braking
Cruise Grade Braking operates while Cruise Control
is engaged in Tow/Haul mode to assist in maintaining
vehicle speed under loaded vehicle conditions. Cruise
Grade Braking assists when driving on a downhill grade.
It maintains vehicle speed by automatically implementing
a shift schedule that uses the engine and the
transmission to slow the vehicle. If vehicle speed is
above the desired speed the transmission will downshift
to slow the vehicle. If vehicle speed is near or below
desired speed the trans will upshift, allowing vehicle
speed to increase.
While in the Range Select Mode (RSM) mode, cruise
grade braking is not available.
SeeAutomatic Transmission Operation on page 2-32.
Full-Time Four-Wheel Drive
The Full-Time Four-Wheel Drive transfer case 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 the vehicle
powertrain and tires. Do not drive in Four-Wheel
High Lock or Four-Wheel Low Lock on pavement
for extended periods.
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N (Neutral):Shift the transfer case to N (Neutral) only
when towing the vehicle. SeeRecreational Vehicle
Towing on page 4-50orTowing Your Vehicle on
page 4-50for more information.
Indicator lights in the dial show 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 the 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 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 the vehicle to your dealer/retailer for service.
See “Service 4WD message” underDriver Information
Center (DIC) on page 3-46.
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 ON/RUN and the vehicle must be stopped or moving
less than 3 mph (5 km/h) with the transmission in
N (Neutral). The preferred method for shifting into
Four-Wheel Low Lock is to have the 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 the
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 3-56
for 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 the vehicle to have engagement noise
and bump when shifting between Four-Wheel Low Lock,
Full-Time Four-Wheel Drive or Four-Wheel-High Lock
ranges or from N (Neutral) with the engine running.
2-39

If the Four-Wheel-Low Lock position is selected when
the 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 the vehicle is moving
less than 3 mph (5 km/h) and the transmission is
in N (Neutral). After 15 seconds the transfer case
will return to the setting last chosen.
Shifting Out of Four-Wheel Low Lock
To shift from Four-Wheel-Low Lock to Full-Time
Four-Wheel Drive or Four-Wheel-High Lock, the vehicle
must be stopped or moving less than 3 mph (5 km/h)
with the transmission in N (Neutral) and the ignition in
ON/RUN. The preferred method for shifting out of
Four-Wheel-Low Lock is to have the vehicle moving
1 to 2 mph (1.6 to 3.2 km/h). Turn the dial to the
Full-Time Four-Wheel Drive or Four-Wheel-High Lock
position. You must wait for the Full-Time Four-Wheel
Drive or Four-Wheel-High Lock indicator light to stop
ashing and remain lit before shifting the transmission
into gear.It is normal for the vehicle to have engagement noise
and bump when shifting between Four-Wheel Low Lock,
Full-Time Four-Wheel Drive or Four-Wheel-High Lock
ranges or from N (Neutral) with the engine running.
If the Full-Time Four-Wheel Drive or
Four-Wheel-High Lock position is selected when
the vehicle is in gear and/or moving, the Full-Time
Four-Wheel Drive or Four-Wheel-High Lock indicator
light will ash for 30 seconds but will not complete
the shift unless the vehicle is moving less than 3 mph
(5 km/h) and the transmission is in N (Neutral).
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.
2-40

Shifting into Neutral
To shift the transfer case to N (Neutral) do the following:
1. Make sure the vehicle is parked so that it will
not roll.
2. Set the parking brake and apply the regular brake
pedal. SeeParking Brake on page 2-42.
3. Start the vehicle or turn the ignition to ON/RUN.
4. Put the transmission in N (Neutral).
5. Shift the transfer case to Full-Time Four-Wheel
Drive.
6. Turn the transfer case dial clockwise to N (Neutral)
position. The transfer case will not shift to N (Neutral)
unless this position is held for 10 seconds. The
N (Neutral) light will come on and then the dial can
be slowly released. The dial will be in the Four-Wheel
Low Lock position but the transfer case will be in
N (Neutral) with the N (Neutral) light on.
7. If the engine is running, make sure that the transfer
case is in N (Neutral) by shifting the transmission
to R (Reverse) for one second, then shift the
transmission to D (Drive) for one second.
8. Turn the ignition to ACC/ACCESSORY, which will
turn the engine off.
9. Place the transmission shift lever in P (Park).10. Release the parking brake prior to moving the
vehicle.
11. Turn the ignition to LOCK/OFF.
Shifting Out of Neutral
To shift out of N (Neutral) do the following:
1. Set the parking brake and apply the regular brake
pedal.
2. Shift the transmission to N (Neutral) and turn the
ignition to ON/RUN with the engine off.
3. Turn the transfer case dial to Full-Time Four-Wheel
Drive, Four-Wheel High Lock or Four-Wheel
Low Lock.
After the transfer case has shifted out of N (Neutral)
the N (Neutral) light will go out.
4. Release the parking brake prior to moving the
vehicle.
Notice:Shifting the transmission into gear before
the requested mode indicator light has stopped
ashing could damage the transfer case. To help
avoid damaging the vehicle, always wait for the
mode indicator lights to stop ashing before
shifting the transmission into gear.
5. Start the engine and shift the transmission to the
desired position.
2-41

Shifting Into Park
{CAUTION:
It can be dangerous to get out of the vehicle if the
shift lever is not fully in P (Park) with the parking
brake rmly set. The vehicle can roll. If you have
left the engine running, the vehicle can move
suddenly. You or others could be injured. To be
sure the vehicle will not move, even when you are
on fairly level ground, use the steps that follow.
If you are pulling a trailer, seeTowing a Trailer
on page 4-55.
1. Hold the brake pedal down and set the parking
brake. SeeParking Brake on page 2-42for more
information.
2. Move the shift lever into P (Park) by pressing the
button on the shift lever and pushing the lever all
the way toward the front of the vehicle.
3. Turn the ignition key to LOCK/OFF.
4. Remove the key and take it with you. If you can
leave the vehicle with the key, the vehicle is in
P (Park).
Leaving the Vehicle With the Engine
Running
{CAUTION:
It can be dangerous to leave the vehicle with the
engine running. The vehicle could move suddenly if
the shift lever is not fully in P (Park) with the parking
brake rmly set. And, if you leave the vehicle with
the engine running, it could overheat and even
catch re. You or others could be injured. Do not
leave the vehicle with the engine running.
If you have to leave the vehicle with the engine running,
be sure the vehicle is in P (Park) and the parking
brake is rmly set before you leave it. After you have
moved the shift lever into P (Park), hold the regular
brake pedal down. Then, see if you can move the shift
lever away from P (Park) without rst pressing the
button on the console shift lever. If you can, it means
that the shift lever was not fully locked into P (Park).
2-43

Parking Over Things That Burn
{CAUTION:
Things that can burn could touch hot exhaust
parts under the vehicle and ignite. Do not park
over papers, leaves, dry grass, or other things that
can burn.
Engine Exhaust
{CAUTION:
Engine exhaust contains Carbon Monoxide (CO)
which cannot be seen or smelled. Exposure to CO
can cause unconsciousness and even death.
CAUTION: (Continued)
CAUTION: (Continued)
Exhaust may enter the vehicle if:
The vehicle idles in areas with poor ventilation
(parking garages, tunnels, deep snow that
may block underbody airow or tail pipes).
The exhaust smells or sounds strange or
different.
The exhaust system leaks due to corrosion or
damage.
The vehicle’s exhaust system has been
modied, damaged or improperly repaired.
There are holes or openings in the vehicle
body from damage or after-market
modications that are not completely sealed.
If unusual fumes are detected or if it is suspected
that exhaust is coming into the vehicle:
Drive it only with the windows
completely down.
Have the vehicle repaired immediately.
Never park the vehicle with the engine running in an
enclosed area such as a garage or a building that
has no fresh air ventilation.
2-45