2010 HUMMER H3 tow

9-72 Driving and Operating
Towing with a Stability Control
System
When towing, the sound of the
stability control system might be
heard. The system is reacting to the
vehicle movement caused by the
trailer, which mainly occurs during
cornering. This is normal when
towing heavier trailers.
Following Distance
Stay at least twice as far behind the
vehicle ahead as you would when
driving the vehicle without a trailer.
This can help to avoid situations
that require heavy braking and
sudden turns.
Passing
More passing distance is needed
when towing a trailer. Because the
rig is longer, it is necessary to go
much farther beyond the passed
vehicle before returning to the lane.
Backing Up
Hold the bottom of the steering
wheel with one hand. Then, to move
the trailer to the left, 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. The vehicle could be
damaged. Avoid making very
sharp turns while trailering.
When turning with a trailer, make
wider turns than normal. Do this
so the trailer won't 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 the instrument panel
flash whenever signaling a turn or
lane change. Properly hooked up,
the trailer lamps also flash, telling
other drivers the vehicle is turning,
changing lanes or stopping.
When towing a trailer, the arrows on
the instrument panel flash for turns
even if the bulbs on the trailer are
burned out. For this reason you
may think other drivers are seeing
the 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 gear before starting down a
long or steep downgrade. If the
transmission is not shifted down, the
brakes might have to be used so
much that they would get hot and no
longer work well.

Driving and Operating 9-73
Vehicles with an automatic
transmission can tow in D (Drive).
Shift the transmission to a lower
gear if the transmission shifts too
often under heavy loads and/or
hilly conditions. For vehicles with a
manual transmission, 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 the engine is turned off
immediately after towing at high
altitude on steep uphill grades, the
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 P (Park)
for a few minutes before turning the
engine off. For vehicles with manualtransmissions, 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 the overheat warning
comes on, see
Engine Overheating
on page 10‑22.
Parking on Hills
{WARNING
Parking the vehicle on a hill
with the trailer attached can be
dangerous. If something goes
wrong, the rig could start to move.
People can be injured, and both
the vehicle and the trailer can be
damaged. When possible, always
park the rig on a flat surface. If parking the rig on a hill:
1. Press the brake pedal, but do
not shift into P (Park) yet for
vehicles with an automatic
transmission, or into gear
for vehicles with a manual
transmission. Turn the 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 brake pedal
until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking brake and shift
into P (Park) for vehicles with an
automatic transmission or into
gear for vehicles with a manual
transmission.
5. Release the brake pedal.

9-74 Driving and Operating
Leaving After Parking on a Hill
1. Apply and hold the brake pedalwhile you:
.start the 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
The vehicle needs service more
often when pulling a trailer. See this
manual's Maintenance Schedule
or Index for more information.
Things that are especially important
in trailer operation are automatic
transmission fluid, engine oil, axle lubricant, belts, cooling system and
brake system. It is a good idea to
inspect these before and during
the trip.
Check periodically to see that all
hitch nuts and bolts are tight.
Engine Cooling When Trailer
Towing
The cooling system may temporarily
overheat during severe operating
conditions. See
Engine Overheating
on page 10‑22.
Trailer Towing
Three important considerations
have to do with weight:
.The weight of the trailer.
.The weight of the trailer tongue.
.The total weight on the vehicle's
tires.
Weight of the Trailer
How heavy can a trailer safely be?
Speed, altitude, road grades,
outside temperature, special
equipment, and the amount of
tongue weight the vehicle can carry
must be considered. 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 a vehicle can weigh,
based on the vehicle model and
options.

9-76 Driving and Operating
Ask your dealer for our trailering
information or advice, or write us at
our Customer Assistance Offices.
SeeCustomer Assistance Offices
on page 13‑3for more information.
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 the vehicle. The Gross
Vehicle Weight (GVW) includes the
curb weight of the vehicle, any
cargo carried in it, and the people
who will be riding in the vehicle.
If there are a lot of options,
equipment, passengers or cargo in
the vehicle, it will reduce the tongue
weight the vehicle can carry, which
will also reduce the trailer weight the
vehicle can tow. If towing a trailer,
the tongue load must be added to
the GVW because the vehicle will
be carrying that weight, too. See
Vehicle Load Limits
on page 9‑27for more information about the
vehicle's maximum load capacity.
If a weight-carrying hitch or a
weight-distributing hitch is being
used, the trailer tongue (A) should
weigh 10‐15 percent of the total
loaded trailer weight (B) up to a
maximum of 227 kg (500 lbs).
After loading the trailer, weigh
the trailer and then the tongue,
separately, to see if the weights are
proper. If they are not, adjustments
might be made by moving some
items around in the trailer. Trailering may 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 the
trailering capacity more than the
total of the additional weight.
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.
If the spare tire carrier is mounted
on the back of the vehicle and the
hitch extension is too short, the
spare tire may interfere with trailer
coupling or trailer tongue jack
operation on some types of trailers.

9-78 Driving and Operating
Total Weight on the Vehicle's
Tires
Inflate the vehicle's tires to the
upper limit for cold tires. These
numbers can be found on the
Certification label or seeVehicle
Load Limits
on page 9‑27. Do
not go over the GVW limit for the
vehicle, or the GAWR, including the
weight of the trailer tongue.
Towing Equipment
Hitches
It is important to have the correct
hitch equipment. Crosswinds, large
trucks going by and rough roads are
a few reasons why the right hitch is
needed. The rear bumper on the vehicle is
not intended for hitches. Do not
attach rental hitches or other
bumper-type hitches to it. Use only
a frame-mounted hitch that does not
attach to the bumper.
Will any holes be made in the body
of the vehicle when the trailer hitch
is installed? If there are, then be
sure to seal the holes when the
hitch is removed. If the holes are not
sealed, dirt, water, and deadly
carbon monoxide (CO) from the
exhaust may get into the vehicle.
See
Engine Exhaust on page 9‑40. Weight-Distributing Hitches and
Weight Carrying Hitches(A) Body-to-Ground Distance (B)
Front of Vehicle
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.

Driving and Operating 9-79
Safety Chains
Always attach chains between the
vehicle and the 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
the rig can turn. Never allow safety
chains to drag on the ground.
Trailer Brakes
A loaded trailer that weighs more
than 680 kg (1,500 lbs) needs to
have its own brake system that
is adequate for the weight of the
trailer. Be sure to read and follow
the instructions for the trailer brakes
so they are installed, adjusted and
maintained properly.
Trailer Wiring Harness
Light‐Duty Trailer Wiring Package
If the vehicle does not have 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
To add a trailer towing wiring
package, have it installed by
your dealer or a qualified service
center. Also, see Add-On Electrical
Equipment
on page 9‑81for more
information. Heavy-Duty Trailer Wiring Package
If the vehicle has 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.

9-80 Driving and Operating
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 charging a remote (non‐vehicle)
battery, turn on the headlamps to
boost the vehicle system voltage to
properly charge the battery. Four-Wire Harness Adapter
If towing a light-duty trailer with
a standard four-way, flat pin
connector, an adapter is available
from your dealer.
Hold the adapter with the tab
pointing up.
Connect the adapter to the
seven‐pin universal heavy‐duty
trailer connector attached to the
bracket on the hitch platform. The
flip cap on the vehicle's harness
locks onto the tab and helps hold
the adapter in place. Plug the
four-way pin connector onto the
adapter.

Driving and Operating 9-81
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
has the following wires:
.Red Wire: AUX B+
.Black Wire: Ground
.Light Blue Wire: Brake Signal
.Dark Blue Wire: Trailer Brakes
Trailer Recommendations
Subtract the hitch loads from the
Cargo Weight Rating (CWR). CWR
is the maximum weight of the load
the vehicle can carry. It does not
include the weight of the people
inside, but you can figure about
68 kg (150 lbs) for each passenger.
The total cargo load must not be
more than the vehicles CWR.
Weigh the vehicle with the trailer
attached, so the GVWR or GAWR
are not exceeded. If using a
weight-distributing hitch, weigh the
vehicle without the spring bars in
place.
The best performance is obtained
by correctly spreading out the
weight of the load and choosing the
correct hitch and trailer brakes.
For more information seeTrailer
Towing on page 9‑74.
Conversions and
Add-Ons
Add-On Electrical
Equipment
Notice: Do not add anything
electrical to the vehicle unless
you check with your dealer first.
Some electrical equipment can
damage the vehicle and the
damage would not be covered
by the vehicle's warranty. Some
add-on electrical equipment can
keep other components from
working as they should.
Add-on equipment can drain the
vehicle battery, even if the vehicle is
not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle
on page 3‑40and Adding
Equipment to the Airbag-Equipped
Vehicle on page 3‑40.