tow HUMMER H2 2007 Service Manual

Towing
Towing Your Vehicle
Consult your dealer or a professional towing
service if you need to have your disabled vehicle
towed. SeeRoadside Assistance Program on
page 542.
If you want to tow your vehicle behind another
vehicle for recreational purposes (such as behind
a motorhome), see “Recreational Vehicle
Towing” following.
Recreational Vehicle Towing
Recreational vehicle towing means towing your
vehicle behind another vehicle – such as behind a
motorhome. The two most common types of
recreational vehicle towing are known as “dinghy
towing” (towing your vehicle with all four wheels
on the ground) and “dolly towing” (towing
your vehicle with two wheels on the ground and
two wheels up on a device known as a “dolly”).With the proper preparation and equipment, many
vehicles can be towed in these ways. See “Dinghy
Towing” and “Dolly Towing,” following.
Here are some important things to consider before
you do recreational vehicle towing:
What’s the towing capacity of the towing
vehicle? Be sure you read the tow vehicle
manufacturer’s recommendations.
How far will you tow? Some vehicles have
restrictions on how far and how long they
can tow.
Do you have the proper towing equipment?
See your dealer or trailering professional
for additional advice and equipment
recommendations.
Is your vehicle ready to be towed? Just as
you would prepare your vehicle for a long
trip, you’ll want to make sure your vehicle is
prepared to be towed. SeeBefore Leaving on
a Long Trip on page 349.
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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 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).
SeeFull-Time Four-Wheel Drive on
page 128for 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 357.
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.
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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.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
level the vehicle after loading or unloading.
The system will suspend transitioning between
the designed ride height and the extended
ride height if any of the doors are open. However,
the system will not suspend operation during
normal leveling and 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.
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Towing a Trailer
{CAUTION:
If you do not use the correct equipment
and drive properly, you can lose control
when you pull a trailer. For example, if the
trailer is too heavy, the brakes may not
work well — or even at all. You and your
passengers could be seriously injured.
Pull a trailer only if you have followed all
the steps in this section. Ask your dealer
for advice and information about towing a
trailer with your vehicle.Notice:Pulling a trailer improperly can
damage your vehicle and result in costly repairs
not covered by your warranty. To pull a trailer
correctly, follow the advice in this part, and see
your dealer for important information about
towing a trailer with your vehicle.
To identify the trailering capacity of your vehicle,
you should read the information in “Weight of
the Trailer” that appears later in this section.
Trailering is different than just driving your vehicle
by itself. Trailering means changes in handling,
acceleration, 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.
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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 mode is used when using your vehicle to
pull a large or heavy load or trailer. Tow/haul is
also useful while pulling 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 accelerator pedal activity when pulling a
heavy trailer or a large or heavy load.
Tow/haul mode is most effective when the vehicle
and trailer combined weight is at least 75 percent 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 mode.
The indicator light on the instrument panel will
turn off. The vehicle will automatically turn
off tow/haul mode every time it is started.
Driving with tow/haul mode 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. It can also 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
6000 V8 (SUV) 4.10 6,700 lbs (3 039 kg) 13,500 lbs (6 123 kg)
6000 V8 (SUT)* 4.10 6,600 lbs (2 994 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.
*Sport utility truck (SUT) models are neither designed nor intended to tow 5th wheel or gooseneck trailers.
You can ask your dealer for our trailering
information or advice, or you can write us at our
Customer Assistance Offices. SeeCustomer
Assistance Offices on page 540for more
information.
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Weight of the Trailer Tongue
The tongue load (A) of any trailer is an important
weight to measure because it affects the total
gross weight of your vehicle. The Gross Vehicle
Weight (GVW) includes the curb weight of
the vehicle, any cargo you may carry in it, and the
people who will be riding in the vehicle. If you
have a lot of options, equipment, passengers or
cargo in your vehicle, it will reduce the tongue
weight your vehicle can carry, which will also
reduce the trailer weight your vehicle can tow. If
you will tow a trailer, you must add the tongue load
to the GVW because your vehicle will be carrying
that weight, too. SeeLoading Your Vehicle on
page 362for more information about your vehicle’s
maximum load capacity.The trailer tongue weight (A) should be 10 percent
to 15 percent of the total loaded trailer weight (B),
up to a maximum of 500 lbs (227 kg) with a weight
carrying hitch. The trailer tongue weight (A) should
be 10 percent to 15 percent of the total loaded
trailer weight (B), up to a maximum of
700 lbs (318 kg) with a weight distributing hitch.
Do not exceed the maximum allowable tongue
weight for your vehicle. Choose the shortest hitch
extension that will position the hitch ball closest
to the vehicle. This will help reduce the effect
of trailer tongue weight on the rear axle.
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Hitches
It’s important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads
are a few reasons why you’ll need the right hitch.
Weight-Distributing Hitches and Weight
Carrying Hitches
When using a weight-distributing hitch, the hitch
must be adjusted so that the distance (A) remains
the same both before and after coupling the
trailer to the tow vehicle.If you will be pulling a trailer that, when loaded,
will weigh more than 5,000 lbs (2 268 kg) be sure
to use a properly mounted weight-distributing
hitch and sway control of the proper size.
This equipment is very important for proper
vehicle loading and good handling when driving.
You should always use a sway control if your
trailer will weigh more than these limits. You can
ask a hitch dealer about sway controls.
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.
(A) Body-to-Ground Distance (B) Front of Vehicle
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Trailer Brakes
If your trailer weighs more than 2,000 lbs (900 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.
Your trailer brake system can tap into the
vehicle’s hydraulic brake system only if:
The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.
The trailer’s brake system will use less than
0.02 cubic inch (0.3 cc) of uid from your
vehicle’s master cylinder. Otherwise,
both braking systems won’t work well.
You could even lose your brakes.
If everything checks out this far, make the brake
tap at the port on the master cylinder that
sends the uid to the rear brakes. But don’t use
copper tubing for this. If you do, it will bend
and nally break off. Use steel brake tubing.
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.
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