brake HUMMER H3 2008 Workshop Manual

Trailer Brake Control Wiring Harness
The trailer brake control wiring harness is located
under the instrument panel to the right of the steering
column. The wires are taped to the harness that goes
to the courtesy light under the instrument panel.
The harness will contain the following wires:
Red Wire: AUX B+
Black Wire: Ground
Light Blue Wire: Brake Signal
Dark Blue Wire: Trailer Brakes
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 4-50.
4-62

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

Service
For service and parts needs, visit your dealer/retailer.
You will receive genuine GM parts and GM-trained and
supported service people.
Genuine GM parts have one of these marks:
Accessories and Modications
When non-dealer/non-retailer accessories are added to
your vehicle they can affect your vehicle’s performance
and safety, including such things as, airbags, braking,
stability, ride and handling, emissions systems,
aerodynamics, durability, and electronic systems like
antilock brakes, traction control and stability control.
Some of these accessories could even cause
malfunction or damage not covered by warranty.
GM Accessories are designed to complement and
function with other systems on your vehicle. Your
GM dealer/retailer can accessorize your vehicle using
genuine GM Accessories. When you go to your
GM dealer/retailer and ask for GM Accessories, you will
know that GM-trained and supported service technicians
will perform the work using genuine GM Accessories.
Also, seeAdding Equipment to Your Airbag-Equipped
Vehicle on page 1-68.
5-3

Checking Things Under
the Hood
{CAUTION:
An electric fan under the hood can start up
and injure you even when the engine is not
running. Keep hands, clothing, and tools away
from any underhood electric fan.
{CAUTION:
Things that burn can get on hot engine parts
and start a re. These include liquids like fuel,
oil, coolant, brake uid, windshield washer and
other uids, and plastic or rubber. You or
others could be burned. Be careful not to drop
or spill things that will burn onto a hot engine.
Hood Release
To open the hood, do the following:
1. Pull the handle with
this symbol on it. It is
located inside the
vehicle on the lower
left side of the
instrument panel.
2. Release the secondary latch on the hood. It is
located below the front center of the hood.
3. Lift the hood.
Before closing the hood, be sure all the ller caps are
on properly. Then pull the hood down and close it rmly.
5-11

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

If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little uid can damage
your transmission. Too much can mean that some
of the uid could come out and fall on hot engine
parts or exhaust system parts, starting a re.
Too little uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission uid.
Wait at least 30 minutes before checking the
transmission uid level if you have been driving:
When outside temperatures are above 90°F (32°C).
At high speed for quite a while.
In heavy traffic — especially in hot weather.
While pulling a trailer.
To get the right reading, the uid should be at normal
operating temperature, which is 180°F to 200°F
(82°C to 93°C).
Get the vehicle warmed up by driving about
15 miles (24 km) when outside temperatures are above
50°F (10°C). If it is colder than 50°F (10°C), drive
the vehicle in THIRD (3) until the engine temperature
gage moves and then remains steady for 10 minutes.A cold uid check can be made after the vehicle has
been sitting for eight hours or more with the engine off,
but this is used only as a reference. Let the engine
run at idle for ve minutes if outside temperatures are
50°F (10°C) or more. If it is colder than 50°F (10°C), you
may have to idle the engine longer. Should the uid
level be low during this cold check, you must check the
uid hot before adding uid. Checking the uid hot
will give you a more accurate reading of the uid level.
Checking the Fluid Level
Prepare your vehicle as follows:
1. Park your vehicle on a level place. Keep the engine
running.
2. With the parking brake applied, place the shift lever
in PARK (P).
3. With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, position
the shift lever in PARK (P).
4. Let the engine run at idle for three minutes or more.
5-22

Brakes
Brake Fluid
The brake master cylinder
reservoir is lled with
DOT-3 brake uid. See
Engine Compartment
Overview on page 5-12for
the location of the
reservoir.
There are only two reasons why the brake uid level
in the reservoir might go down. The rst is that the brake
uid goes down to an acceptable level during normal
brake lining wear. When new linings are put in, the uid
level goes back up. The other reason is that uid
is leaking out of the brake hydraulic system.
If it is, you should have the brake hydraulic system
xed, since a leak means that sooner or later the
brakes will not work well.It is not a good idea to top off the brake uid. Adding
brake uid will not correct a leak. If uid is added when
the linings are worn, there will be too much uid
when new brake linings are installed. Add or remove
brake uid, as necessary, only when work is done on the
brake hydraulic system.
{CAUTION:
If you have too much brake uid, it can spill on
the engine. The uid will burn if the engine is
hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
uid only when work is done on the brake
hydraulic system. See “Checking Brake Fluid”
in this section.
Refer to the Maintenance Schedule to determine when
to check your brake uid. SeeScheduled Maintenance
on page 6-4.
5-38

Checking Brake Fluid
The brake uid can be checked without taking off the
cap by looking at the brake uid reservoir.
The uid level should be above MIN. If it is not, have
the brake hydraulic system checked to see if there is
a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.
What to Add
When you do need brake uid, use only DOT-3 brake
uid. Use new brake uid from a sealed container
only. SeeRecommended Fluids and Lubricants on
page 6-12.
Always clean the brake uid reservoir cap and the area
around the cap before removing it. This helps keep
dirt from entering the reservoir.
{CAUTION:
With the wrong kind of uid in the brake
hydraulic system, the brakes might not work
well. This could cause a crash. Always use the
proper brake uid.
Notice:
Using the wrong uid can badly damage brake
hydraulic system parts. For example, just a
few drops of mineral-based oil, such as engine
oil, in the brake hydraulic system can damage
brake hydraulic system parts so badly that they
will have to be replaced. Do not let someone
put in the wrong kind of uid.
If you spill brake uid on your vehicle’s painted
surfaces, the paint nish can be damaged. Be
careful not to spill brake uid on your vehicle. If
you do, wash it off immediately. SeeWashing
Your Vehicle on page 5-95.
5-39

Brake Wear
Your vehicle has disc brakes. Disc brake pads have
built-in wear indicators that make a high-pitched warning
sound when the brake pads are worn and new pads
are needed. The sound can come and go or be heard all
the time your vehicle is moving, except when you are
pushing on the brake pedal rmly.
{CAUTION:
The brake wear warning sound means that
soon the brakes will not work well. That could
lead to an accident. When you hear the brake
wear warning sound, have your vehicle
serviced.
Notice:Continuing to drive with worn-out brake
pads could result in costly brake repair.
Some driving conditions or climates can cause a brake
squeal when the brakes are rst applied or lightly
applied. This does not mean something is wrong with
the brakes.Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly tighten wheel nuts in
the proper sequence to torque specications in
Capacities and Specifications on page 5-107.
Brake linings should always be replaced as complete
axle sets.
Brake Pedal Travel
See your dealer/retailer if the brake pedal does not
return to normal height, or if there is a rapid increase in
pedal travel. This could be a sign that brake service
might be required.
Brake Adjustment
Every time you make a brake stop, the disc brakes
adjust for wear.
5-40