trailer HUMMER H2 2008 Owner's Manual

Your spare tire carrier is behind the tailgate. If your
hitch extension is too short, the spare tire may interfere
with trailer coupling or trailer tongue jack operation
on some types of trailers.
After you have loaded your trailer, weigh the trailer and
then the tongue, separately, to see if the weights are
proper. If they are not, you may be able to get them right
simply by moving some items around in the trailer.
Trailering may also be limited by the vehicle’s ability to
carry tongue weight. Tongue weight cannot cause
the vehicle to exceed the GVWR (Gross Vehicle Weight
Rating) or the RGAWR (Rear Gross Axle Weight
Rating). The effect of additional weight may reduce
your trailering capacity more than the total of the
additional weight.Consider the following example:
A vehicle model base weight is 5,500 lbs (2 495 kg);
2,800 lbs (1 270 kg) at the front axle and 2,700 lbs
(1 225 kg) at the rear axle. It has a GVWR of 7,200 lbs
(3 266 kg), a RGAWR of 4,000 lbs (1 814 kg) and a
GCWR (Gross Combination Weight Rating) of 14,000 lbs
(6 350 kg). The trailer rating should be:
You can expect tongue weight to be at least 10 percent of
trailer weight (850 lbs (386 kg)) and because the weight
is applied well behind the rear axle, the effect on the rear
axle will be greater than just the weight itself, as much as
1.5 times as much. The weight at the rear axle could be
850 lbs (386 kg) X 1.5 = 1,275 lbs (578 kg). Since the
rear axle already weighs 2,700 lbs (1 225 kg), adding
1,275 lbs (578 kg) brings the total to 3,975 lbs (1 803 kg).
This is very close to, but within the limit for RGAWR as
well. The vehicle is set to trailer up to 8,500 lbs (3 856 kg).
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But let’s say your specic vehicle is equipped with some
of the latest options and you have a front seat passenger
and two rear seat passengers with some luggage and
gear in the vehicle as well. You may add 300 lbs (136 kg)
to the front axle weight and 400 lbs (181 kg) to the rear
axle weight. Your vehicle now weighs:
Weight is still below 7,200 lbs (3 266 kg) and you may
think that you should subtract 700 additional pounds
(318 kg) from your trailering capacity to stay within
GCWR limits. Your maximum trailer would only be
7,800 lbs (3 538 kg). You may go further and think you
must limit tongue weight to less than 1,000 lbs (454 kg)
to avoid exceeding GVWR. But, you must still consider
the effect on the rear axle. Because your rear axle now
weighs 3,100 lbs (1 406 kg), you can only put 900 lbs
(408 kg) on the rear axle without exceeding RGAWR.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.
Total Weight on Your Vehicle’s Tires
Be sure your vehicle’s tires are inated to the upper
limit for cold tires. You will nd these numbers on
the Certication label at the rear edge of the driver’s
door or seeLoading Your Vehicle on page 4-44.
Then be sure you don’t go over the GVW limit for your
vehicle, or the GAWR, including the weight of the
trailer tongue. If you use a weight distributing hitch,
make sure you don’t go over the rear axle limit before
you apply the weight distribution spring bars.
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Hitches
It is 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/retailer 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.
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.
(A) Body-to-Ground Distance (B) Front of Vehicle
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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.
Following Distance
Stay at least twice as far behind the vehicle ahead as
you would when driving your vehicle without a trailer.
This can help you avoid situations that require
heavy braking and sudden turns.
Passing
You will need more passing distance up ahead when
you’re towing a trailer. Because you are a good deal
longer, you will need to go much farther beyond the
passed vehicle before you can return to your lane.
Backing Up
Hold the bottom of the steering wheel with one hand.
Then, to move the trailer to the left, just move that hand
to the left. To move the trailer to the right, move your
hand to the right. Always back up slowly and, if possible,
have someone guide you.
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Making Turns
Notice:Making very sharp turns while trailering
could cause the trailer to come in contact with the
vehicle. Your vehicle could be damaged. Avoid
making very sharp turns while trailering.
When you are turning with a trailer, make wider turns
than normal. Do this so your trailer will not strike
soft shoulders, curbs, road signs, trees or other objects.
Avoid jerky or sudden maneuvers. Signal well in
advance.
Turn Signals When Towing a Trailer
The arrows on your instrument panel will ash whenever
you signal a turn or lane change. Properly hooked up,
the trailer lamps will also ash, telling other drivers
you’re about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel will ash for turns even if the bulbs on the trailer
are burned out. Thus, you may think drivers behind
you are seeing your signal when they are not. It is
important to check occasionally to be sure the trailer
bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gearbeforeyou start
down a long or steep downgrade. If you do not shift down,
you might have to use your brakes so much that they
would get hot and no longer work well.
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).
You may also want to activate the tow/haul mode if the
transmission shifts too often. See “Tow/Haul Mode”
earlier.
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. If you do get the overheat
warning, seeEngine Overheating on page 5-27.
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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 is
how to do it:
1. Apply your regular brakes, but do not shift into
PARK (P) yet.
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).
5. Release the regular brakes.
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 (do not
overll), 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 are trailering, it is a good idea to review these
sections before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
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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.
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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.
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If No Steam Is Coming From
Your Engine
The ENGINE OVERHEATED IDLE ENGINE message,
along with a low coolant condition, can indicate a
serious problem.
If you get an engine overheat warning, but see or hear
no steam, the problem may not be too serious.
Sometimes the engine can get a little too hot when you:
Climb a long hill on a hot day.
Stop after high-speed driving.
Idle for long periods in traffic.
Tow a trailer. SeeTowing a Trailer on page 4-55.
If you get the ENGINE COOLANT HOT message with
no sign of steam, try this for a minute or so:
1. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
2. If you are in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving — DRIVE (D).
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not come back on, you can drive
normally.
If the warning continues and you have not stopped, pull
over, stop, and park your vehicle right away.If there is still no sign of steam, push down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you are parked. If you still have the warning, turn off the
engine and get everyone out of the vehicle until it
cools down. Also, see “Overheated Engine Protection
Operating Mode” later in this section.
You may decide not to lift the hood but to get service
help right away.
Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
ENGINE POWER IS REDUCED message is displayed,
an overheat protection mode which alternates ring
groups of cylinders helps prevent engine damage. In this
mode, you will notice a loss in power and engine
performance. This operating mode allows your vehicle
to be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair the
cause of coolant loss, change the oil and reset the oil
life system. SeeEngine Oil on page 5-13.
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5. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the engine
cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches the FULL COLD mark.
6. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
7. Verify coolant level after engine is shut off and the
coolant is cold. If necessary, repeat coolant ll
procedure steps 1 through 7.
Engine Fan Noise
If your vehicle has a clutched engine cooling fan, when
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the fan is spinning slower and the clutch is
not fully engaged. This improves fuel economy and
reduces fan noise. Under heavy vehicle loading, trailer
towing, and/or high outside temperatures, the fan
speed increases as the clutch more fully engages, so
you may hear an increase in fan noise. This is normal
and should not be mistaken as the transmission slipping
or making extra shifts. It is merely the cooling system
functioning properly. The fan will slow down when
additional cooling is not required and the clutch
disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If your vehicle has electric cooling fans, you may hear
the fans spinning at low speed during most everyday
driving. The fans may turn off if no cooling is required.
Under heavy vehicle loading, trailer towing, and/or
high outside temperatures, or if you are operating your
air conditioning system, the fans may change to
high speed and you may hear an increase in fan noise.
This is normal and indicates that the cooling system
is functioning properly. The fans will change to low
speed when additional cooling is no longer required.
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