trailer HUMMER H3 2010 Owner's Manual

Driving and Operating 9-77
Consider the following example:
A vehicle model base weight is
2 495 kg (5,500 lbs); 1 270 kg
(2,800 lbs) at the front axle and
1 225 kg (2,700 lbs) at the rear
axle. It has a GVWR of 3 266 kg
(7,200 lbs), a RGAWR of 1 814 kg
(4,000 lbs) and a GCWR (Gross
Combination Weight Rating) of
6 350 kg (14,000 lbs). The trailer
rating should be:
Expect tongue weight to be at least
10 percent of trailer weight (386 kg
(850 lbs)) and because the weight is
applied well behind the rear axle,
the effect on the rear axle is greater
than just the weight itself, as much
as 1.5 times as much. The weight
at the rear axle could be 386 kg
(850 lbs) X 1.5 = 578 kg (1,275 lbs).Since the rear axle already weighs
1 225 kg (2,700 lbs), adding 578 kg
(1,275 lbs) brings the total to
1 803 kg (3,975 lbs). This is very
close to, but within the limit for
RGAWR as well. The vehicle is set
to trailer up to 3 856 kg (8,500 lbs).
If the vehicle has many options and
there is a front seat passenger and
two rear seat passengers with some
luggage and gear in the vehicle as
well. 136 kg (300 lbs) could be
added to the front axle weight and
181 kg (400 lbs) to the rear axle
weight. The vehicle now weighs:
Weight is still below 3 266 kg
(7,200 lbs) and you might think
318 additional kilograms (700 lbs)
should be subtracted from the
trailering capacity to stay within
GCWR limits. The maximum trailerwould only be 3 538 kg (7,800 lbs).
You may go further and think the
tongue weight should be limited
to less than 454 kg (1,000 lbs) to
avoid exceeding GVWR. But the
effect on the rear axle must still be
considered. Because the rear axle
now weighs 1 406 kg (3,100 lbs),
408 kg (900 lbs) can be put on
the rear axle without exceeding
RGAWR. The effect of tongue
weight is about 1.5 times the actual
weight. Dividing the 408 kg (900 lbs)
by 1.5 leaves only 272 kg (600 lbs)
of tongue weight that can be
handled. Since tongue weight is
usually at least 10 percent of total
loaded trailer weight, expect that
the largest trailer the vehicle can
properly handle is 2 722 kg
(6,000 lbs).
It is important that the vehicle
does not exceed any of its
ratings
—GCWR, GVWR, RGAWR,
Maximum Trailer Rating or Tongue
Weight. The only way to be sure it is
not exceeding any of these ratings
is to weigh the vehicle and trailer.

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.

Vehicle Care 10-13
Notice:Too much or too
little fluid can damage the
transmission. Too much can
mean that some of the fluid could
come out and fall on hot engine
parts or exhaust system parts,
starting a fire. Too little fluid
could cause the transmission to
overheat. Be sure to get an
accurate reading if checking the
transmission fluid.
Wait at least 30 minutes before
checking the transmission fluid level
if you have been driving:
.When outside temperatures are
above 32°C (90°F).
.At high speed for quite a while.
.In heavy traffic —especially in
hot weather.
.While pulling a trailer.
To get the right reading, the fluid
should be at normal operating
temperature, which is 82°C to 93°C
(180°F to 200°F). Get the vehicle warmed up by
driving about 24 km (15 miles) when
outside temperatures are above
10°C (50°F). If it is colder than 10°C
(50°F), drive the vehicle in 3 (Third)
until the engine temperature gauge
moves and then remains steady for
10 minutes.
A cold fluid 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 five minutes if outside
temperatures are 10°C (50°F) or
more. If it is colder than 10°C
(50°F), the engine might have to
idle longer. Should the fluid level be
low during this cold check, check
the fluid hot before adding fluid.
Checking the fluid hot gives a more
accurate reading of the fluid level.
Checking the Fluid Level
To prepare the vehicle:
1. Park the vehicle on a level
place. Keep the engine running.
2. With the parking brake applied, place the shift lever in P (Park).
3. With your foot on the brake pedal, move the shift lever
through each gear range,
pausing for about three seconds
in each range. Then, position the
shift lever in P (Park).
4. Let the engine run at idle for three minutes or more.

Vehicle Care 10-23
If Steam Is Coming From The
Engine Compartment
{WARNING
Steam from an overheated engine
can burn you badly, even if you
just open the hood. Stay away
from the engine if you see or hear
steam coming from it. Just turn it
off and get everyone away from
the vehicle until it cools down.
Wait until there is no sign of
steam or coolant before you open
the hood.
If you keep driving when your
engine is overheated, the liquids
in it can catch fire. You or others
could be badly burned. Stop your
engine if it overheats, and get out
of the vehicle until the engine
is cool.
If No Steam Is Coming From
The Engine Compartment
If an engine overheat warning is
displayed but no steam can be seen
or heard, the problem may not be
too serious. Sometimes the engine
can get a little too hot when the
vehicle:
.Climbs a long hill on a hot day.
.Stops after high-speed driving.
.Idles for long periods in traffic.
.Tows a trailer. See“Driving on
Grades” underTrailer Towingon
page 9‑74.
If the overheat warning is displayed
with no sign of steam:
1. Turn the air conditioning off.
2. Turn the heater on to the highest temperature and to the highest
fan speed. Open the windows as
necessary. 3. In heavy traffic, let the engine
idle in N (Neutral) while stopped.
If it is safe to do so, pull off
the road, shift to P (Park) or
N (Neutral) and let the
engine idle.
If the temperature overheat gauge
is no longer in the overheat zone
or an overheat warning no longer
displays, the vehicle can be driven.
Continue to drive the vehicle slow
for about 10 minutes. Keep a safe
vehicle distance from the car in front
of you. If the warning does not come
back on, continue to drive normally.
If the warning continues, pull
over, stop, and park the vehicle
right away.
If there is no sign of steam, idle
the engine for three minutes while
parked. If the warning is still
displayed, turn off the engine until
it cools down.

10-24 Vehicle Care
Engine Fan
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 Overviewon page 10‑6for reservoir location.
When to Check Power Steering
Fluid
It is not necessary to regularly
check power steering fluid unless a
leak in the system is suspected or
an unusual noise is heard. A fluid
loss in this system could indicate a
problem. Have the system inspected
and repaired.
How to Check Power Steering
Fluid
1. Turn the key off and let the
engine compartment cool down.
2. Wipe the cap and the top of the reservoir clean.
3. Unscrew the cap and wipe the dipstick with a clean rag.
4. Replace the cap and completely tighten it.
5. Then remove the cap again and look at the fluid level on the
dipstick.
The level should be between the
ADD and FULL marks. If necessary,
add only enough fluid to bring the
level up to the proper range.

10-42 Vehicle Care
FuseUsage
39 Daytime Running
Lamps
40 Passenger Side
Headlamp
41 Driver Side
Headlamp
42 Trailer
Back-Up Lamp
43 Front Park Lamps
44 Air Injection Reactor
(AIR) Solenoid
45 Auxiliary Power 2/
Cigarette Lighter
46 Electronic Throttle
Control
47 Oxygen Sensor
48 Air Conditioning
Clutch
49 Rear Park Lamp
50 Stop Lamp Fuse
Usage
51 Auxiliary Power 1/
Cigarette Lighter
52 StabiliTrak
®,
Antilock Brake
System
53 Power Heated Seat,
Belt Switch
54 Fuel System Control
Module (FSCM)
55 Trailer Parking
Lamps
56 Front Turn Signal,
Hazard Signal,
Courtesy Mirror
57 Power Sunroof
58 Transfer Case
Control Module
Switch
59 Climate Controls
Control Head
60 Back‐Up Lamp
61 Power Seats Fuse Usage
62 Air Injection Reactor
(AIR) Pump
63 Passenger Side
Power Window
64 Antilock Brake
System,
StabiliTrak
®2
Solenoid
67 Antilock Brake
System,
StabiliTrak
®1 Motor
68 Driver Side Power
Window
82 Climate Control Fan
83 Electronic Brake
Controller
84 Trailer B+ Fuse
85 Starter
91 Generator Megafuse

10-90 Vehicle Care
Towing
Towing the Vehicle
To avoid damage, the disabled
vehicle should be towed with all
four wheels off the ground. Consult
your dealer or a professional towing
service if the disabled vehicle must
be towed. SeeRoadside Service
on
page 13‑5.
To tow the 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 the vehicle behind
another vehicle–such as behind
a motorhome. The two most
common types of recreational
vehicle towing are known as “dinghy
towing” — towing the vehicle with
all four wheels on the ground, and “dolly towing” —
towing the vehicle
with two wheels on the ground and
two wheels up on a device known
as a “dolly”.
Here are some important things to
consider before recreational vehicle
towing:
.What is the towing capacity of
the tow vehicle? Be sure to read
the tow vehicle manufacturer's
recommendations.
.What is the distance that will be
travelled? Some vehicles have
restrictions on how far and how
long they can tow.
.Is the proper towing equipment
going to be used? See your
dealer or trailering professional
for additional advice and
equipment recommendations.
.Is the vehicle ready to be
towed? Just as preparing the
vehicle for a long trip, make sure
the vehicle is prepared to be
towed.
Dinghy Towing
This full‐time four‐wheel‐drive
vehicle can be dinghy towed from
the front. These vehicles can also
be towed by placing them on a
platform trailer with all four wheels
off the ground. These vehicles
cannot be towed using a dolly.