engine HUMMER H2 2004 Repair Manual

{CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. Your brakes will have
to do all the work of slowing down. 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 your engine running and your vehicle in
gear when you go downhill.
Know how to go uphill. You may want to shift down
to a lower gear. The lower gears help cool your
engine and transmission, and you can climb the
hill better.
Stay in your own lane when driving on two-lane
roads in hills or mountains. Do not swing wide
or cut across the center of the road. Drive at speeds
that let you stay in your own lane.
As you go over the top of a hill, be alert. There
could be something in your lane, like a stalled
car or an accident.
You may see highway signs on mountains that
warn of special problems. Examples are long
grades, passing or no-passing zones, a falling rocks
area or winding roads. Be alert to these and take
appropriate action.
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If You Are Caught in a Blizzard
If you are stopped by heavy snow, you could be in a
serious situation. You should probably stay with
your vehicle unless you know for sure that you are near
help and you can hike through the snow. Here are
some things to do to summon help and keep yourself
and your passengers safe:
Turn on your hazard ashers.
Tie a red cloth to your vehicle to alert police that
you have been stopped by the snow.
Put on extra clothing or wrap a blanket around you.
If you have no blankets or extra clothing, make
body insulators from newspapers, burlap bags, rags,
oor mats — anything you can wrap around
yourself or tuck under your clothing to keep warm.
You can run the engine to keep warm, but be careful.
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{CAUTION:
Snow can trap exhaust gases under your
vehicle. This can cause deadly CO (carbon
monoxide) gas to get inside. CO could
overcome you and kill you. You can not see it
or smell it, so you might not know it is in your
vehicle. Clear away snow from around the
base of your vehicle, especially any that is
blocking your exhaust pipe. And check around
again from time to time to be sure snow does
not collect there.
Open a window just a little on the side of the
vehicle that is away from the wind. This will
help keep CO out.Run your engine only as long as you must. This saves
fuel. When you run the engine, make it go a little
faster than just idle. That is, push the accelerator
slightly. This uses less fuel for the heat that you get and
it keeps the battery charged. You will need a
well-charged battery to restart the vehicle, and possibly
for signaling later on with your headlamps. Let the
heater run for a while.
Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine
again and repeat this only when you feel really
uncomfortable from the cold. But do it as little as
possible. Preserve the fuel as long as you can. To help
keep warm, you can get out of the vehicle and do
some fairly vigorous exercises every half hour or so until
help comes.
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If You Are Stuck: In Sand, Mud, Ice
or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you do not want to
spin your wheels too fast. The method known as
“rocking” can help you get out when you are stuck, but
you must use caution.
{CAUTION:
If you let your tires spin at high speed, they
can explode, and you or others could be injured.
And, the transmission or other parts of the
vehicle can overheat. That could cause an
engine compartment re or other damage.
When you are stuck, spin the wheels as little as
possible. Do not spin the wheels above 35 mph
(55 km/h) as shown on the speedometer.
Notice:Spinning your wheels can destroy parts of
your vehicle as well as the tires. If you spin the
wheels too fast while shifting your transmission
back and forth, you can destroy your transmission.
For more information about using tire chains on your
vehicle, seeTire Chains on page 5-75.
Rocking Your Vehicle To Get It Out
First, turn your steering wheel left and right. That will
clear the area around your front wheels. Your vehicle
has a Traction Control System that will activate when the
system senses that the wheels are spinning. See
Traction Control System (TCS) on page 4-9for more
information. Then, with the wheels straight ahead, shift
back and forth between REVERSE (R) and a forward
gear, spinning the wheels as little as possible. Release
the accelerator pedal while you shift, and press
lightly on the accelerator pedal when the transmission is
in gear. By slowly spinning your wheels in the forward
and reverse directions, you will cause a rocking
motion that may free your vehicle. If that does not get
you out after a few tries, you may need to be towed out.
Or, you can use your recovery loops. If you do need
to be towed out, seeTowing Your Vehicle on page 4-65.
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Dinghy Towing
Use the following procedure to tow your vehicle:
1. Shift the transmission to PARK (P).
2. Turn the engine off, but leave the ignition on.
3. Firmly set the parking brake.
4. Securely attach the vehicle being towed to the
tow vehicle.
5. Shift the transfer case to NEUTRAL (N). See
All-Wheel Drive on page 2-25for the proper
procedure to select the NEUTRAL position for
your vehicle.
6. Release the parking brake only after the vehicle
being towed is rmly attached to the towing
vehicle. You can use your vehicle’s front mounted
receiver with the proper accessories to tow it.
See “Front Mounted Receiver” underIf You Are
Stuck: In Sand, Mud, Ice or Snow on page 4-56.
7. Turn the engine off and leave the steering column
unlocked.{CAUTION:
Shifting an all-wheel-drive vehicle’s transfer
case into NEUTRAL can cause your vehicle to
roll even if the transmission is in Park (P). You
or others could be injured. Make sure the
parking brake is rmly set before you shift the
transfer case to NEUTRAL.
Dolly Towing
Your vehicle can not be dolly towed. If you must tow
your vehicle behind another, use the dinghy towing
procedure listed previously.
Notice:Dolly towing your vehicle will damage
drivetrain components. Do not dolly tow your
vehicle.
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Selectable Extended Rear Ride
Height
If your vehicle has this feature it comes as part of the
electronically controlled air suspension system.
The selectable rear ride height allows you to raise the
rear of the vehicle about 2 inches (5 cm) over the normal
ride height. This can be helpful when driving off-road
where you may need more ground clearance to clear
an obstacle.
The button that controls
this feature is located on
the instrument panel to the
right of the steering wheel.To use this feature, ensure that the following conditions
are met:
The engine must be running.
All doors must be fully closed. The suspension will
not raise or lower if a door is open.
The vehicle speed must be less than 40 mph
(64 km/h). The system will not activate otherwise.
Press the height control button to raise the rear of the
vehicle.
A light in the button will begin to ash as the rear of the
vehicle rises. Once the extended height has been
reached (this may take up to a minute), the warning
light will stop ashing and will stay lit while the vehicle is
at the extended height.
To lower the vehicle to the normal ride height, press the
button again. The light in the button will ash as the
suspension lowers. When the light in the button stops
ashing and goes out, the suspension has reached
the normal ride height.
This feature will lower the vehicle to the normal height if
vehicle speed exceeds 40 mph (64 km/h).
You may also want to use this feature when ascending,
descending or cresting a steep hill as this can help
prevent the rear bumper from dragging on the base of
the hill or prevent the vehicle from grounding out
(high centering) on the crest of the hill.
Do not use this feature when towing a trailer.
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Electronically Controlled Air
Suspension System
The electronically controlled air suspension, if equipped,
keeps the rear of your vehicle level as you load and
unload it. The system includes a compressor, two height
sensor and two air springs supporting the vehicle.
The engine must be running for the system to operate
and level the vehicle after loading or unloading. The
system will suspend leveling if any of the doors and/or
the liftgate are open. Once the doors are closed,
system leveling will continue.
You may hear the compressor running when you load
your vehicle, and periodically as the system adjusts
the vehicle to the standard ride height. You may
also hear the release of air similar to a hissing sound
during suspension operation. This is normal.
Load leveling will not function normally with the inator
hose attached to the inator outlet. Remove the
inater hose from the outlet when it is not in use. See
Accessory Inator on page 5-76.
Overload and Overheat Protection
Overload protection is designed to protect the air
suspension system and is an indication to the driver that
the vehicle is overloaded.
If the rear suspension remains at a low height, the rear
axle load has exceeded GAWR (Gross Axle Weight
Rating). When the overload protection mode is activated,
the compressor operates for about 30 seconds to one
minute without raising the vehicle depending on the
amount of overload. This will continue each time
the ignition is turned on until the rear axle load is
reduced below GAWR.
If the total rear GAWR (Gross Axle Weight Rating) is
reached, the suspension may be slightly less than level.
This is normal and does not mean there is a problem
with the air suspension.
If the system overheats, it will shut down and stop all
leveling functions until the system cools down.
During this time the SERVICE AIR SUSPENSION
message will appear in the DIC. SeeDriver Information
Center (DIC) on page 3-44for more information.
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If yours was built with trailering options, as many are,
it’s ready for heavier trailers. But trailering is different
than just driving your vehicle by itself. Trailering means
changes in handling, accelleration, braking, durability
and fuel economy. Successful, safe trailering takes
correct equipment, and it has to be used properly.
That’s the reason for this part. In it are many time-tested,
important trailering tips and safety rules. Many of
these are important for your safety and that of your
passengers. So please read this section carefully before
you pull a trailer.
If You Do Decide To Pull A Trailer
If you do, here are some important points:
There are many different laws, including speed limit
restrictions, having to do with trailering. Make sure
your rig will be legal, not only where you live
but also where you’ll be driving. A good source for
this information can be state or provincial police.
Consider using a sway control. See “Hitches” later
in this section.
Don’t tow a trailer at all during the rst 500 miles
(800 km) your new vehicle is driven. Your engine,
axle or other parts could be damaged.
Then, during the rst 500 miles (800 km) that you
tow a trailer, don’t drive over 50 mph (80 km/h)
and don’t make starts at full throttle. This helps your
engine and other parts of your vehicle wear in at
the heavier loads.
You can tow in DRIVE (D). You may want to shift
the transmission to THIRD (3) or, if necessary, a
lower gear selection if the transmission shifts
too often (e.g., under heavy loads and/or hilly
conditions). See “Tow/Haul Mode” following.
Three important considerations have to do with weight:
the weight of the trailer,
the weight of the trailer tongue
and the weight on your vehicle’s tires.
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Tow/Haul Mode
Tow/haul is designed to assist while your vehicle is
pulling a large or heavy load or trailer. Tow/haul is most
useful while pulling such a load in rolling terrain, in
stop-and-go traffic, or when you need improved
low-speed control, such as when parking. The purpose
of the tow/haul mode is to do the following:
Reduce the frequency and improve the predictability
of transmission shifts when pulling a heavy trailer or
a large or heavy load.
Provide the same solid shift feel when pulling a
heavy trailer or a large or heavy load as when
the vehicle is unloaded.
Improve control of vehicle speed while requiring
less throttle pedal activity when pulling a heavy
trailer or a large or heavy load.
Tow/haul is designed to be most effective when the
vehicle and trailer combined weight is at least 75% of the
vehicle’s Gross Combination Weight Rating (GCWR).
See “Weight of the Trailer” later in this section.Press the button on the
instrument panel to the
right of the steering
wheel to enable the
tow/haul mode.
A light on the instrument
panel will illuminate to
indicate that tow/haul
mode has been selected.
Press the button again to turn off tow/haul. The indicator
light on the instrument panel will turn off. The vehicle will
automatically turn off tow/haul every time it is started.
Driving with tow/haul activated without a heavy load or
with no trailer will cause reduced fuel economy and
unpleasant engine and transmission driving
characteristics, but will not cause damage.
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Weight of the Trailer
How heavy can a trailer safely be?
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to pull
a trailer are all important. And, it can also depend
on any special equipment that you have on your vehicle.Use one of the following charts to determine how much
your vehicle can weigh, based upon your vehicle
model and options.
Maximum trailer weight is calculated assuming only the
driver is in the tow vehicle and it has all the required
trailering equipment. The weight of additional optional
equipment, passengers and cargo in the tow vehicle
must be subtracted from the maximum trailer weight.
Engine Axle Ratio*Maximum Trailer
Weight **GCWR
6000 V8 4.10 6,700 lbs. (3 039 kg) 13,500 lbs. (6 123 kg)
**The Gross Combination Weight Rating (GCWR) in the total allowable weight of the completely loaded vehicle and
trailer including any passengers, cargo, equipment and conversions. The GCWR for your vehicle should not be
exceeded.
You can ask your dealer for our trailering information or
advice, or you can write us at the address listed in
your Warranty and Owner Assistance Information
Booklet.In Canada, write to:
General Motors of Canada Limited
Customer Communication Centre, 163-005
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7
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