2008 HUMMER H2 battery

You must wait for the light in the button to stop ashing
and remain illuminated before the rear axle is locked.
Notice:If you try to lock the rear axle while your
vehicle is stuck and the tires are spinning, you could
damage your vehicle’s drivetrain. The repairs
would not be covered by your warranty. Always lock
the rear axle before attempting situations and/or
navigating terrain which could possibly cause
the vehicle to become stuck.
The locking rear axle will be disengaged when the
vehicle’s speed is greater than 40 mph (64 km/h), if the
vehicle’s battery is low and/or the transfer case is
shifted out of Four-Wheel-Low-Lock mode.
Notice:If you lock the rear axle while driving
on pavement, you could damage your vehicle’s
drivetrain. The repairs would not be covered by
your warranty. Do not use the locking rear axle
on pavement.
StabiliTrak®System
Your vehicle has the StabiliTrak®system which
combines Antilock brake, traction and stability control
systems and helps the driver maintain directional control
of the vehicle in most driving conditions.When you rst start your vehicle and begin to drive
away, the system performs several diagnostic checks to
ensure there are no problems. You may hear or feel
the system working. This is normal and does not mean
there is a problem with your vehicle. The system
should initialize before the vehicle reaches 20 mph
(32 km/h). In some cases, it may take approximately
two miles of driving before the system initializes.
If the system fails to turn on or activate, the StabiliTrak
®
light along with one of the following messages will be
displayed on the Driver Information Center (DIC):
TRACTION CONTROL OFF, SERVICE TRACTION
CONTROL, STABILITRAK OFF, SERVICE
STABILITRAK. If these DIC messages appear, make
sure the StabiliTrak
®system has not been turned
off using the StabiliTrak®on/off button. If this clears
the message(s), your vehicle does not need servicing.
If this does not clear the message(s), then turn the
vehicle off, wait 15 seconds, and then turn it back on
again to reset the system. If any of these messages still
appear on the Driver Information Center (DIC), your
vehicle should be taken in for service. For more
information on the DIC messages, seeDriver
Information Center (DIC) on page 3-49.
4-7

You can run the engine to keep warm, but be careful.
{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 cannot 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 the 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 the headlamps. Let the
heater run for a while.
4-38

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 in
ACCESSORY.
3. Firmly set the parking brake.
4. Securely attach the vehicle being towed to the
tow vehicle.
{CAUTION:
Shifting a full-time four-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.
5. Shift the transfer case to NEUTRAL (N). See
Full-Time Four-Wheel Drive on page 2-36for
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 Your Vehicle
is Stuck in Sand, Mud, Ice, or Snow on page 4-39.
7. Turn the ignition to ACCESSORY.
8. Disconnect the battery if you are going to tow for
long distances or long periods of time.
When towing your vehicle for extended periods of time,
start your vehicle as often as possible to prevent
battery drain. This should only be done when the tow
vehicle is parked.Dolly Towing
Your vehicle cannot 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.
4-52

Trailer Wiring Harness
Heavy-Duty Trailer Wiring Harness
Package
Your vehicle is equipped with the seven-wire trailer
towing harness. This harness with a seven-pin universal
trailer connector is attached to a bracket on the hitch
platform.The seven-wire harness contains the following trailer
circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Red/Black: Battery Feed*
Dark Blue: Trailer Brake*
*There is a location in the Underhood Fuse Block for
these circuits, but they are not connected. They should
be connected, and proper fuses installed, by your
dealer/retailer or a qualied service center.
If you are charging a remote (non-vehicle) battery, press
the Tow/Haul mode button located at the end of the shift
lever. This will boost the vehicle system voltage and
properly charge the battery.
4-66

Electric Brake Control Wiring
Provisions
These wiring provisions are included with your vehicle
as part of the trailer wiring package. These provisions
are for an electric brake controller. The instrument panel
contains blunt cut wires near the data link connector
for the trailer brake controller. The harness contains the
following wires:
Dark Blue: Brake Signal to Trailer Connector
Red/Black: Battery
Light Blue/White: Brake Switch
White: Ground
It should be installed by your dealer/retailer or a
qualied service center.
Trailer Recommendations
You must subtract your hitch loads from the Cargo
Weight Rating (CWR). CWR is the maximum weight of
the load your vehicle can carry. It doesn’t include the
weight of the people inside, but you can gure about
150 lbs. (68 kg) for each seat. The total cargo load must
not be more than your vehicles CWR.
Weigh your vehicle with your trailer attached, so that
you won’t go over the GVWR or GAWR. If you are using
a weight-distributing hitch, weigh the vehicle without
the spring bars in place.
You’ll get the best performance if you spread out the
weight of your load the right way, and if you choose the
correct hitch and trailer brakes.
For more information seeTowing a Trailer on page 4-55.
4-67

Service............................................................5-3
Accessories and Modications..........................5-3
California Proposition 65 Warning.....................5-3
California Perchlorate Materials Requirements.....5-4
Doing Your Own Service Work.........................5-4
Adding Equipment to the Outside of
Your Vehicle..............................................5-4
Fuel................................................................5-5
Gasoline Octane............................................5-5
Gasoline Specications....................................5-5
California Fuel...............................................5-5
Additives.......................................................5-6
Fuels in Foreign Countries...............................5-6
Filling the Tank..............................................5-7
Filling a Portable Fuel Container.......................5-9
Checking Things Under the Hood.....................5-9
Hood Release..............................................5-10
Engine Compartment Overview.......................5-12
Engine Oil...................................................5-13
Engine Oil Life System..................................5-16
Engine Air Cleaner/Filter................................5-18
Automatic Transmission Fluid.........................5-21
Engine Coolant.............................................5-24
Coolant Surge Tank Pressure Cap..................5-26
Engine Overheating.......................................5-27Overheated Engine Protection
Operating Mode.........................................5-28
Cooling System............................................5-29
Engine Fan Noise.........................................5-33
Power Steering Fluid.....................................5-34
Windshield Washer Fluid................................5-35
Brakes........................................................5-36
Battery........................................................5-39
Jump Starting...............................................5-40
Rear Axle.......................................................5-45
Four-Wheel Drive............................................5-46
Front Axle......................................................5-47
Bulb Replacement..........................................5-48
Halogen Bulbs..............................................5-48
Headlamps..................................................5-48
Front Turn Signal and Parking Lamps..............5-49
Daytime Running Lamps (DRL).......................5-50
Roof Marker Lamps......................................5-50
Taillamps, Turn Signal, Stoplamps and
Back-up Lamps.........................................5-51
Replacement Bulbs.......................................5-53
Windshield Wiper Blade Replacement..............5-54
Tires..............................................................5-55
Tire Sidewall Labeling...................................5-56
Tire Terminology and Denitions.....................5-58
Section 5 Service and Appearance Care
5-1

A. Coolant Surge Tank. SeeCooling System on
page 5-29andCoolant Surge Tank Pressure Cap
on page 5-26.
B. Engine Air Cleaner/Filter and Air Filter Restriction
Indicator (If Equipped). SeeEngine Air Cleaner/Filter
on page 5-18.
C. Windshield Washer Fluid Reservoir. See “Adding
Washer Fluid” underWindshield Washer Fluid
on page 5-35.
D. Engine Oil Fill Cap. See “When to Add Engine Oil”
underEngine Oil on page 5-13.
E. Engine Oil Dipstick. See “Checking Engine Oil”
underEngine Oil on page 5-13.
F. Air Filter Restriction Indicator (If Equipped).
SeeEngine Air Cleaner/Filter on page 5-18.
G. Automatic Transmission Fluid Dipstick. See
“Checking the Fluid Level” underAutomatic
Transmission Fluid on page 5-21.
H. Engine Cooling Fan. SeeCooling System on
page 5-29.
I. Remote Negative (−) Terminal (GND). SeeJump
Starting on page 5-40.
J. Power Steering Fluid Reservoir (Out of View).
SeePower Steering Fluid on page 5-34.K. Remote Positive (+) Terminal. SeeJump Starting on
page 5-40.
L. Brake Fluid Reservoir. See “Brake Fluid” under
Brakes on page 5-36.
M. Underhood Fuse Block. SeeUnderhood Fuse Block
on page 5-113.
N. Battery. SeeBattery on page 5-39.
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.
SeeEngine Compartment Overview on page 5-12
for 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.
5-13

Replacing Brake System Parts
The braking system on a vehicle is complex. Its many
parts have to be of top quality and work well together
if the vehicle is to have really good braking.
Your vehicle was designed and tested with top-quality
brake parts. When you replace parts of the braking
system — for example, when the brake linings wear down
and you need new ones put in — be sure you get new
approved replacement parts. If you do not, the brakes
might not work properly. For example, if someone puts in
brake linings that are wrong for your vehicle, the balance
between the front and rear brakes can change — for the
worse. The braking performance you have come to
expect can change in many other ways if someone puts
in the wrong replacement brake parts.
Battery
Your vehicle has a maintenance free battery. When it
is time for a new battery, see your dealer/retailer for
one that has the replacement number shown on
the original battery’s label. SeeEngine Compartment
Overview on page 5-12for battery location.
Warning:Battery posts, terminals, and related
accessories contain lead and lead compounds,
chemicals known to the State of California to cause
cancer and reproductive harm. Wash hands after
handling.
Vehicle Storage
{CAUTION:
Batteries have acid that can burn you and gas
that can explode. You can be badly hurt if
you are not careful. SeeJump Starting on
page 5-40for tips on working around a battery
without getting hurt.
Infrequent Usage: If you drive your vehicle infrequently,
remove the black, negative (−) cable from the battery.
This will help keep the battery from running down.
Extended Storage: For extended storage of your vehicle,
remove the black, negative (−) cable from the battery
or use a battery trickle charger. This will help maintain
the charge of the battery over an extended period
of time.
5-39