trailer HUMMER H3 2007 Owner's Manual

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’ll need more passing distance up ahead when
you’re towing a trailer. Because you’re a good
deal longer, you’ll 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.
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’re turning with a trailer, make wider
turns than normal. Do this so your trailer
won’t strike soft shoulders, curbs, road signs,
trees or other objects. Avoid jerky or sudden
maneuvers. Signal well in advance.
304

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’s important to check occasionally to
be sure the trailer bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gearbefore
you start down a long or steep downgrade. If you
don’t shift down, you might have to use your
brakes so much that they would get hot and no
longer work well.
If you have an automatic transmission, 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
under heavy loads and/or hilly conditions.If you have a manual transmission and you
are towing a trailer, it is better not to use the
highest gear.
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.
For manual transmissions, let the engine run
while parked, preferably on level ground, with the
transmission out of gear and the parking brake
applied, for a few minutes before turning the
engine off. If you do get the overheat warning,
seeEngine Overheating on page 338.
305

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’s how to do it:
1. Apply your regular brakes, but don’t shift into
PARK (P) yet for an automatic transmission,
or into gear for a manual transmission.
Turn your wheels into the curb if facing
downhill or into traffic if facing uphill.
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) for an
automatic transmission or into gear for a
manual transmission.
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.
306

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, 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’re trailering, it’s a good idea to review
these sections before you start your trip.
Check periodically to see that all hitch nuts
and bolts are tight.
Trailer Wiring Harness
Light-Duty Trailer Wiring Package
If your vehicle is not equipped with a trailer
towing package, the chassis harness will
contain the following blunt cut circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
White: Ground
Brown: Tail Lamps
If you want to add on a trailer tow, it should be
installed by your dealer or a qualied service
center. Also, seeAdd-On Electrical Equipment
on page 416for more information.
307

Heavy-Duty Trailer Wiring Package
If your vehicle is equipped with a trailer towing
package, the rear bumper harness will have
a seven-pin universal heavy-duty trailer connector
attached to a bracket on the hitch platform.The trailer towing harness contains the following
seven trailer circuits:
Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Red: Battery Feed
Dark Blue: Trailer Brake
If you are charging a remote (non-vehicle) battery,
turn on the headlamps to boost the vehicle
system voltage to properly charge the battery.
308

Four-Wire Harness Adapter
If you need to tow a light-duty trailer with a
standard four-way, at pin connector, an adapter
is available from your dealer.
Use this adapter to
connect a standard
four-way pin connector
to the seven-wire
harness on your vehicle.
Connect the adapter with the tab pointing up.
The ip cap on the vehicle’s seven-wire harness
will lock onto the tab (see arrow in the previous
graphic) and help hold the adapter in place.
Plug the four-way pin connector onto the adapter.
309

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 297.
310

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).
330

CAUTION: (Continued)
You or others could be badly burned.
Stop your engine if it overheats, and get
out of the vehicle until the engine is cool.
Notice:If your engine catches re because
you keep driving with no coolant, your vehicle
can be badly damaged. The costly repairs
would not be covered by your warranty.
If No Steam Is Coming From Your
Engine
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. See “Driving on Grades” under
Towing a Trailer on page 297.If you get the overheat warning with no sign of
steam, try this for a minute or so:
1. In heavy traffic, let the engine idle in
NEUTRAL while stopped. If it is safe to do so,
pull off the road, shift to PARK (P) or
NEUTRAL and let the engine idle.
2. Turn off the air conditioning.
3. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
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, pull over, stop, and park
your vehicle right away.
If there is still no sign of steam, idle the engine for
three minutes while you are parked. 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.
You may decide not to lift the hood but to get
service help right away.
339

Engine Fan Noise
This 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 clutch is not
engaged. This improves fuel economy and reduces
fan noise. Under heavy vehicle loading, trailer
towing and/or high outside temperatures, the
fan speed increases when the clutch 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
disengages.
Power Steering Fluid
SeeEngine
Compartment Overview
on page 322for
reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power
steering uid unless you suspect there is a leak
in the system or you hear an unusual noise.
A uid loss in this system could indicate a problem.
Have the system inspected and repaired.
345