2008 HUMMER H3 automatic transmission

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.
If you have an automatic transmission, you can tow
in DRIVE (D). You may want to shift the transmission
to THIRD (3) or, if necessary, a lower gear if the
transmission shifts too often under heavy loads
and/or hilly conditions. If you have a manual
transmission and you are towing a trailer, it is
better not to use the highest gear.
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
4-51

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. It can depend on any special equipment that
you have on your vehicle, and the amount of tongue
weight the vehicle can carry. See “Weight of the Trailer
Tongue” later in this section for more information.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.
Use the following chart to determine how much
your vehicle can weigh, based upon your vehicle
model and options.
Engine Axle Ratio Maximum Trailer Weight *GCWR
Automatic Transmission, 3.7L Engine 4.56 4,500 lbs (2 041 kg) 9,500 lbs (4 309 kg)
Automatic Transmission, 5.3L Engine 4.10 6,000 lbs (2 721 kg) 11,400 lbs (5 171 kg)
Manual Transmission 4.56 3,000 lbs (1 364 kg) 8,000 lbs (3 629 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.
Ask your dealer/retailer for our trailering information or advice, or write us at our Customer Assistance Offices.
SeeCustomer Assistance Offices on page 7-5for more information.
4-52

Driving On Grades
Reduce speed and shift to a lower gearbeforeyou start
down a long or steep downgrade. If you don’t shift
down, you might have to use your brakes so much
that they would get hot and no longer work well.
If you have an automatic transmission, 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 under heavy loads
and/or hilly conditions.
If you have a manual transmission and you are towing a
trailer, it is better not to use the highest gear.
When towing at high altitude on steep uphill grades,
consider the following: Engine coolant will boil at a lower
temperature than at normal altitudes. If you turn your
engine off immediately after towing at high altitude on
steep uphill grades, your vehicle may show signs similar
to engine overheating. To avoid this, let the engine run
while parked, preferably on level ground, with the
automatic transmission in PARK (P) for a few minutes
before turning the engine off. For manual transmissions,
let the engine run while parked, preferably on level
ground, with the transmission out of gear and the parking
brake applied, for a few minutes before turning the engine
off. If you do get the overheat warning, seeEngine
Overheating on page 5-29.
Parking on Hills
{CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.
But if you ever have to park your rig on a hill, here’s
how to do it:
1. Apply your regular brakes, but don’t shift into
PARK (P) yet for an automatic transmission, or into
gear for a manual transmission. Turn your wheels
into the curb if facing downhill or into traffic if facing
uphill.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake and shift into PARK (P) for an
automatic transmission or into gear for a manual
transmission.
5. Release the regular brakes.
4-58

When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
start your engine,
shift into a gear, and
release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the
chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission uid, engine
oil, axle lubricant, belts, cooling system and brake
system. Each of these is covered in this manual, and
the Index will help you nd them quickly. If you’re
trailering, it’s a good idea to review these sections
before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
Trailer Wiring Harness
Light-Duty Trailer Wiring Package
If your vehicle is not equipped with a trailer towing
package, the chassis harness will contain the following
blunt cut circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
White: Ground
Brown: Tail Lamps
If you want to add on a trailer tow, it should be installed
by your dealer/retailer or a qualied service center.
Also, seeAdd-On Electrical Equipment on page 5-101
for more information.
4-59

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
Your Vehicle..............................................5-5
Fuel................................................................5-5
Gasoline Octane............................................5-5
Gasoline Specications....................................5-5
California Fuel...............................................5-6
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-7
Filling the Tank..............................................5-8
Filling a Portable Fuel Container.....................5-10
Checking Things Under the Hood....................5-11
Hood Release..............................................5-11
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-15
Engine Oil Life System..................................5-18
Engine Air Cleaner/Filter................................5-20
Automatic Transmission Fluid.........................5-21
Manual Transmission Fluid.............................5-24
Hydraulic Clutch...........................................5-26Engine Coolant.............................................5-27
Radiator Pressure Cap..................................5-29
Engine Overheating.......................................5-29
Cooling System............................................5-31
Engine Fan Noise.........................................5-36
Power Steering Fluid.....................................5-36
Windshield Washer Fluid................................5-37
Brakes........................................................5-38
Battery........................................................5-41
Jump Starting...............................................5-42
Rear Axle
.......................................................5-45
Four-Wheel Drive............................................5-46
Front Axle......................................................5-46
Headlamp Aiming...........................................5-46
Bulb Replacement..........................................5-49
Halogen Bulbs..............................................5-49
Headlamps..................................................5-49
Taillamps, Turn Signal, Stoplamps and
Back-up Lamps.........................................5-50
License Plate Lamp......................................5-51
Replacement Bulbs.......................................5-52
Windshield Wiper Blade Replacement..............5-52
Section 5 Service and Appearance Care
5-1

A. Windshield Washer Fluid Reservoir. See “Adding
Washer Fluid” underWindshield Washer Fluid
on page 5-37.
B. Engine Coolant Recovery Tank. SeeEngine Coolant
on page 5-27.
C. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-20.
D. Power Steering Fluid Reservoir. SeePower Steering
Fluid on page 5-36.
E. Automatic Transmission Fluid Dipstick (If Equipped).
See “Checking the Fluid Level” underAutomatic
Transmission Fluid on page 5-21.
F. Engine Oil Fill Cap. See “When to Add Engine Oil”
underEngine Oil on page 5-15.
G. Radiator Pressure Cap. SeeCooling System on
page 5-31.H. Remote Negative (−) Terminal (GND). SeeJump
Starting on page 5-42.
I. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil on page 5-15.
J. Positive (+) Battery Terminal. SeeJump Starting on
page 5-42.
K. Brake Fluid Reservoir. See “Brake Fluid” under
Brakes on page 5-38.
L. Engine Compartment Fuse Block. SeeEngine
Compartment Fuse Block on page 5-103.
M. Battery. SeeBattery on page 5-41.
N. Hydraulic Clutch Fluid Reservoir (If Equipped).
SeeHydraulic Clutch on page 5-26.
5-13

A. Engine Air Cleaner/Filter. SeeEngine Air
Cleaner/Filter on page 5-20.
B. 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 Coolant Recovery Tank. SeeEngine Coolant
on page 5-27.
E. Automatic Transmission Fluid Dipstick (If Equipped).
See “Checking the Fluid Level” underAutomatic
Transmission Fluid on page 5-21.
F. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil on page 5-15.
G. Engine Oil Fill Cap. See “When to Add Engine Oil”
underEngine Oil on page 5-15.
H. Brake Fluid Reservoir. See “Brake Fluid” under
Brakes on page 5-38.
I. Battery. SeeBattery on page 5-41.
J. Power Steering Fluid Reservoir. SeePower Steering
Fluid on page 5-36.
K. Radiator Pressure Cap. SeeCooling System on
page 5-31.
L. Engine Compartment Fuse Block. SeeEngine
Compartment Fuse Block on page 5-103.Engine Oil
Checking Engine Oil
It is a good idea to check the engine oil every time you
get fuel. 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 5-12for
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 you do not do this,
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

{CAUTION:
Operating the engine with the air cleaner/lter
off can cause you or others to be burned.
The air cleaner not only cleans the air; it helps
to stop ames if the engine backres. If it is
not there and the engine backres, you could
be burned. Do not drive with it off, and be
careful working on the engine with the air
cleaner/lter off.
Notice:If the air cleaner/lter is off, a backre can
cause a damaging engine re. And, dirt can easily get
into your engine, which will damage it. Always have
the air cleaner/lter in place when you are driving.
Automatic Transmission Fluid
When to Check and Change Automatic
Transmission Fluid
A good time to check your automatic transmission uid
level is when the engine oil is changed.
Change the uid and lter at the intervals listed in
Additional Required Services on page 6-6, and be sure
to use the transmission uid listed inRecommended
Fluids and Lubricants on page 6-12.
How to Check Automatic
Transmission Fluid
Because this operation can be a little difficult, you may
choose to have this done at the dealer/retailer service
department.
5-21