ECU HUMMER H3 2008 Service Manual

Security Light
For information regarding
this light and the vehicle’s
security system, see
Content Theft-Deterrent on
page 2-14.
Cruise Control Light
This light comes on
whenever you set the
cruise control.
The light goes out when the cruise control is turned off.
SeeCruise Control on page 3-11for more information.
Highbeam On Light
This light comes on when
the high-beam headlamps
are in use.
SeeHeadlamp High/Low-Beam Changer on page 3-9
for more information.
3-39

FLUID
This message displays if the brake uid is low. Check
the brake uid as soon as possible and have your
vehicle serviced by your dealer/retailer. SeeBrakes on
page 5-38for more information. Press and release
the reset stem to acknowledge the message and clear it
from the display.
FUEL CAP
This message displays if the vehicle’s fuel cap is either
off or loose. Pull over as soon as possible and check
to see if the fuel cap is secure. You may also see
the check engine light on the instrument panel cluster.
If the check engine light does come on when the
fuel cap was loose, it may take a few driving trips before
the light turns off. SeeMalfunction Indicator Lamp on
page 3-36for more information if the light still remains
on. Press and release the reset stem to acknowledge
the message and clear it from the display.
LOW FUEL
This message displays if the level of fuel in the vehicle
is low. Also check the fuel gage. SeeFuel Gage on
page 3-40for more information. Rell the fuel tank as
soon as possible.
LOW TIRE
This message displays if a low tire pressure is detected
in any of the vehicle’s tires. Press and release the reset
stem to acknowledge the message and clear it from the
display. The message appears at each ignition cycle until
the tires are inated to the correct ination pressure. See
Tires on page 5-54andInflation - Tire Pressure on
page 5-62for more information on tires and the correct
ination pressures.
OIL
This message displays when the oil pressure is low.
SeeOil Pressure Light on page 3-38andEngine Oil
on page 5-15for more information.
PARK BRK (Brake)
This message displays when the parking brake is set.
SeeParking Brake on page 2-32andBrake System
Warning Light on page 3-33for more information. The
message clears from the display after the parking brake
is released or by pressing and releasing the reset stem.
3-45

Not Found:There are no channels available for the
selected category. The system is working properly.
XM Locked:The XM™ receiver in your vehicle may
have previously been in another vehicle. For security
purposes, XM™ receivers cannot be swapped between
vehicles. If this message is received after having
your vehicle serviced, check with your dealer/retailer.
Radio ID:If tuned to channel 0, this message will
alternate with the XM Radio 8 digit radio ID label.
This label is needed to activate the service.
Unknown:If this message is received when tuned to
channel 0, there may be a receiver fault. Consult
with your dealer/retailer.
Chk XMRcvr:If this message does not clear within a
short period of time, the receiver may have a fault.
Consult with your dealer/retailer.
Navigation/Radio System
Your vehicle may have a navigation radio system.
The navigation system has built-in features intended to
minimize driver distraction. Technology alone, no
matter how advanced, can never replace your own
judgment. See the Navigation System manual for some
tips to help you reduce distractions while driving.
Theft-Deterrent Feature
THEFTLOCK®is designed to discourage theft of your
vehicle’s radio. The feature works automatically by
learning a portion of the Vehicle Identication Number
(VIN). If the radio is moved to a different vehicle, it does
not operate and LOCKED displays.
When the radio and vehicle are turned off, the blinking
red light indicates that THEFTLOCK
®is armed.
With THEFTLOCK
®activated, the radio does not
operate if stolen.
Radio Reception
Frequency interference and static during normal radio
reception can occur if items such as cellphone chargers,
vehicle convenience accessories, and external
electronic devices are plugged into the accessory power
outlet. If there is interference or static, unplug the
item from the accessory power outlet.
3-61

Off-Road Driving
This off-road guide is meant to provide advice for
when you drive your vehicle off paved roads. Also,
seeBraking on page 4-3.
Off-road driving can be great fun. But it does have
some denite hazards. The greatest of these is
the terrain itself.
The airbag system is designed to work properly
under a wide range of conditions, including off-road
usage. Observe safe driving speeds, especially on
rough terrain. As always, wear your safety belt.
“Off-roading” means you have left the great North
American road system behind. Traffic lanes are
not marked. Curves are not banked. There are no
road signs. Surfaces can be slippery, rough, uphill or
downhill. In short, you have gone right back to nature.
Off-road driving involves some new skills. And that
is why it is very important that you read this guide.
You will nd many driving tips and suggestions.
These will help make your off-road driving safer
and more enjoyable.
Before You Go Off-Roading
There are some things to do before you go out.
For example, be sure to have all necessary maintenance
and service work done. Check to make sure all
underbody shields are properly attached. Make sure
any equipment you may need — rst aid kit, cell phone,
ashlight, etc. — is securely stored in the vehicle. Be sure
you read all the information about your four-wheel-drive
vehicle in this manual. Is there enough fuel? Is the spare
tire fully inated? Are the uid levels up where they
should be? What are the local laws that apply to
off-roading where you will be driving? If you do not
know, you should check with law enforcement people
in the area. Will you be on someone’s private land?
If so, be sure to get the necessary permission.
4-12

Loading Your Vehicle for
Off-Road Driving
{CAUTION:
Cargo on the load oor piled higher than
the seatbacks can be thrown forward during
a sudden stop. You or your passengers
could be injured. Keep cargo below the
top of the seatbacks.
Unsecured cargo on the load oor can be
tossed about when driving over rough
terrain. You or your passengers can be
struck by ying objects. Secure the cargo
properly.
Heavy loads on the roof raise the vehicle’s
center of gravity, making it more likely to
roll over. You can be seriously or fatally
injured if the vehicle rolls over. Put heavy
loads inside the cargo area, not on the roof.
Keep cargo in the cargo area as far forward
and low as possible.There are some important things to remember about
how to load your vehicle.
The heaviest things should be on the load oor and
forward of your rear axle. Put heavier items in the
rear area, as far forward as you can.
Be sure the load is secured properly, so driving on
the off-road terrain does not toss things around.
You will nd other important information in this manual.
SeeLoading Your Vehicle on page 4-42andTires
on page 5-54.
4-13

{CAUTION:
If you do not shift down, the brakes 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. Shift down
to let the engine assist the brakes on a steep
downhill slope.
{CAUTION:
Coasting downhill in NEUTRAL (N) or with the
ignition off is dangerous. The brakes will have
to do all the work of slowing down and 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 the engine running and your
vehicle in gear when you go downhill.
Stay in your own lane. Do not swing wide or cut
across the center of the road. Drive at speeds
that let you stay in your own lane.
Top of hills: Be alert — something could be in your
lane (stalled car, accident).
Pay attention to special road signs (falling rocks
area, winding roads, long grades, passing or
no-passing zones) and take appropriate action.
SeeOff-Road Driving on page 4-12for information
about driving off-road.
Winter Driving
Here are some tips for winter driving:
Have your vehicle in good shape for winter.
You might want to put winter emergency supplies in
your vehicle.
Include an ice scraper, a small brush or broom,
a supply of windshield washer uid, a rag, some
winter outer clothing, a small shovel, a ashlight, a
red cloth, and a couple of reective warning triangles.
And, if you will be driving under severe conditions,
include a small bag of sand, a piece of old carpet,
or a couple of burlap bags to help provide traction.
Be sure you properly secure these items in your vehicle.
Also seeTires on page 5-54.
4-35

{CAUTION:
Do not load your vehicle any heavier than
the Gross Vehicle Weight Rating (GVWR),
or either the maximum front or rear Gross
Axle Weight Rating (GAWR). If you do,
parts on your vehicle can break, and it
can change the way your vehicle handles.
These could cause you to lose control
and crash. Also, overloading can shorten
the life of your vehicle.
Using heavier suspension components to get
added durability might not change your weight
ratings. Ask your dealer to help you load
your vehicle the right way.
Notice:Overloading your vehicle may cause
damage. Repairs would not be covered by your
warranty. Do not overload your vehicle.
If you put things inside your vehicle – like
suitcases, tools, packages, or anything else – they
will go as fast as the vehicle goes. If you have
to stop or turn quickly, or if there is a crash, they
will keep going.
{CAUTION:
Things you put inside your vehicle can
strike and injure people in a sudden stop
or turn, or in a crash.
Put things in the cargo area of your
vehicle. Try to spread the weight
evenly.
Never stack heavier things, like
suitcases, inside the vehicle so that
some of them are above the tops of
the seats.
Do not leave an unsecured child
restraint in your vehicle.
When you carry something inside the
vehicle, secure it whenever you can.
Do not leave a seat folded down
unless you need to.
There is also important loading information for
off-road driving in this manual. See
“Loading Your
Vehicle for Off-Road Driving”underOff-Road
Driving on page 4-12.
4-47

Dinghy Towing
Use the following procedure to tow your vehicle:
1. Shift the transmission to NEUTRAL (N).
2. Turn the engine off, but leave the ignition in ON.
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 automatic
transmission is in PARK (P) or the manual
transmission is in any gear. 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 2-27for
the proper procedure to select the NEUTRAL
position for your vehicle.6. Put the transmission in PARK (P) for an
automatic transmission or in FIRST (1) for
a manual transmission.
7. Release the parking brake only after the vehicle
being towed is rmly attached to the towing
vehicle.
8. Turn the ignition off.
After towing, see “Shifting Out of NEUTRAL” under
Full-Time Four-Wheel Drive on page 2-27.
Dolly Towing
Notice:Dolly towing your vehicle will damage
drivetrain components. Do not dolly tow your
vehicle.
Your vehicle cannot be dolly towed. If you must tow
your vehicle behind another, use the dinghy towing
procedure listed previously.
4-49

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

The effect of tongue weight is about 1.5 times the actual
weight. Dividing the 900 lbs (408 kg) by 1.5 leaves you
with being able to handle only 600 lbs (272 kg) of tongue
weight. Since tongue weight is usually at least 10 percent
of total loaded trailer weight, you can expect that the
largest trailer your vehicle can properly handle is
6,000 lbs (2 721 kg).
It is important that you make sure your vehicle does not
exceed any of its ratings — GCWR, GVWR, RGAWR,
Maximum Trailer Rating or Tongue Weight. The
only way to be sure you are not exceeding any
of these ratings is to weigh your vehicle and trailer.
Safety Chains
You should always attach chains between your vehicle
and your trailer. Cross the safety chains under the tongue
of the trailer to help prevent the tongue from contacting
the road if it becomes separated from the hitch. Always
leave just enough slack so you can turn with your rig.
Never allow safety chains to drag on the ground.
Trailer Brakes
If your trailer weighs more than 1,500 lbs (680 kg)
loaded, then it needs its own brakes – and they must be
adequate. Be sure to read and follow the instructions
for the trailer brakes so you’ll be able to install,
adjust and maintain them properly.
Driving with a Trailer
Towing a trailer requires a certain amount of experience.
Before setting out for the open road, you’ll want to get
to know your rig. Acquaint yourself with the feel of
handling and braking with the added weight of the
trailer. And always keep in mind that the vehicle you
are driving is now a good deal longer and not nearly
as responsive as your vehicle is by itself.
Before you start, check all trailer hitch parts and
attachments, safety chains, electrical connector, lamps,
tires and mirror adjustment. If the trailer has electric
brakes, start your vehicle and trailer moving and then
apply the trailer brake controller by hand to be sure
the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to be sure that the
load is secure, and that the lamps and any trailer
brakes are still working.
4-56