tow HUMMER H3 2009 Service Manual

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
Loading the Vehicle on page 4-35
for more information about the
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 or
a weight distributing hitch.
Do not exceed the maximum
allowable tongue weight for the
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.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.
After loading the trailer, weigh the
trailer and then the tongue,
separately, to see if the weights are
proper. If they aren’t, adjustments
might be made by moving some
items around in the trailer.
Driving Your Vehicle 4-45

Total Weight on the Vehicle’s
Tires
Be sure the vehicle’s tires are
inated to the upper limit for cold
tires. These numbers can be found
on the Certication/Tire Label
located on the B-pillar below the
door latch or seeLoading the
Vehicle on page 4-35. Make sure
not to go over the GVW limit for the
vehicle, or the GAWR, including
the weight of the trailer tongue. If
using a weight distributing hitch,
make sure not to go over the rear
axle limit before applying the weight
distribution spring bars.
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.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.
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 can reduce the
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:
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 (A) Body-to-Ground Distance (B)
Front of Vehicle
4-46 Driving Your Vehicle

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 1,500 lbs (680 kg) 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.
Driving with a Trailer
Towing a trailer requires a certain
amount of experience. Get to
know the rig before setting out for
the open road. Get acquainted
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
longer and not as responsive as the
vehicle is by itself.
Before starting, check all trailer hitch
parts and attachments, safety
chains, electrical connectors, lamps,
tires and mirror adjustments. If
the trailer has electric brakes, start
the vehicle and trailer moving
and then apply the trailer brake
controller by hand to be sure
the brakes are working. This checks
the electrical connection at the
same time.
During the 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 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.
4-48 Driving Your Vehicle

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
ash whenever signaling a turn
or lane change. Properly hooked up,
the trailer lamps also ash, telling
other drivers the vehicle is turning,
changing lanes or stopping.When towing a trailer, the arrows
on the instrument panel ash
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
gearbeforestarting 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.
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 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 the
overheat warning comes on,
seeEngine Overheating on
page 5-27.
Driving Your Vehicle 4-49

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 uid, 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.
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/retailer or a qualied
service center. Also, seeAdd-On
Electrical Equipment on page 5-91
for 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.
Driving Your Vehicle 4-51

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, at pin
connector, an adapter is available
from your dealer/retailer.
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 ip 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.
4-52 Driving Your Vehicle

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 gure about
150 lbs. (68 kg) 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 seeTowing a
Trailer on page 4-42.
Driving Your Vehicle 4-53

A.Engine Air Cleaner/Filter on
page 5-17.
B. Air Filter Restriction Indicator
(If Equipped). SeeEngine Air
Cleaner/Filter on page 5-17.
C. Windshield Washer Fluid
Reservoir. See “Adding Washer
Fluid” underWindshield
Washer Fluid on page 5-30.
D. Engine Coolant Recovery Tank.
SeeEngine Coolant on
page 5-23.
E. Automatic Transmission
Fluid Dipstick (If Equipped).
See “Checking the Fluid Level”
underAutomatic Transmission
Fluid on page 5-18.
F. Engine Oil Dipstick. See
“Checking Engine Oil” under
Engine Oil on page 5-13.G. Engine Oil Fill Cap. See “When
to Add Engine Oil” underEngine
Oil on page 5-13.
H. Brake Fluid Reservoir.
See “Brake Fluid” underBrakes
on page 5-30.
I.Battery on page 5-33.
J. Power Steering Fluid Reservoir.
SeePower Steering Fluid on
page 5-29.
K.Engine Compartment Fuse Block
on page 5-92.
L. Radiator Pressure Cap.
SeeCooling System on
page 5-22.Engine Oil
Checking Engine Oil
It is a good idea to check the
engine oil every time you get fuel.
In order to get an accurate reading,
the oil must be warm and the
vehicle must be on level ground.
The engine oil dipstick handle
is a yellow loop. SeeEngine
Compartment Overview on
page 5-10for the location of the
engine oil dipstick.
1. Turn off the engine and give the
oil several minutes to drain back
into the oil pan. If you do not
do this, the oil dipstick might not
show the actual level.
2. Pull out the dipstick and clean it
with a paper towel or cloth,
then push it back in all the way.
Remove it again, keeping the
tip down, and check the level.
Service and Appearance Care 5-13

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.
Then, without shutting off the
engine:
1. Flip the handle up and then pull
out the dipstick and wipe it with
a clean rag or paper towel.The automatic transmission
dipstick handle with this symbol
on it is located in the engine
compartment on the passenger
side of the vehicle.
SeeEngine Compartment
Overview on page 5-10for more
information on location.
2. Push it back in all the way, wait
three seconds, and pull it back
out again.
3. Check both sides of the dipstick,
and read the lower level.
The uid level must be in
the COLD area, below thecross-hatched area, for a
cold check or in the HOT or
cross-hatched area for a
hot check. Be sure to keep the
dipstick pointed down to get
an accurate reading.
4. If the uid level is in the
acceptable range, push
the dipstick back in all the way;
then ip the handle down to
lock the dipstick in place.
How to Add Automatic
Transmission Fluid
Refer to the Maintenance
Schedule to determine what kind
of transmission uid to use.
SeeRecommended Fluids and
Lubricants on page 6-12.
Add uid only after checking the
transmission uid while it is hot.
A cold check is used only as
a reference. If the uid level is low,
add only enough of the proper
uid to bring the level up to the
HOT area for a hot check.
Service and Appearance Care 5-19

Checking Coolant
The vehicle must be on a level
surface when checking the
coolant level.
The coolant recovery tank cap has
this symbol on it.
It is located toward the rear of
the engine compartment on
the passenger side of the vehicle.
SeeEngine Compartment Overview
on page 5-10for more information
on location.
Check to see if coolant is visible in
the coolant recovery tank. If the
coolant inside the coolant recovery
tank is boiling, do not do anythingelse until it cools down. If coolant is
visible but the coolant level is not
at or above the FULL COLD
mark, add a 50/50 mixture of clean,
drinkable water and DEX-COOL
coolant at the coolant recovery tank,
but be sure the cooling system is
cool before this is done.
The vehicle must be on a level
surface. When the engine is cold,
the coolant level should be at FULL
COLD, or a little higher. When
the engine is warm, the level could
be above the FULL COLD level.
When the engine is cold, the coolant
level should be at least up to the
FULL COLD mark. If it is not, there
could be a leak in the cooling
system.
How to Add Coolant to the
Recovery Tank
{CAUTION
You can be burned if you spill
coolant on hot engine parts.
Coolant contains ethylene glycol
and it will burn if the engine parts
are hot enough. Do not spill
coolant on a hot engine.
Notice:This vehicle has a
specic coolant ll procedure.
Failure to follow this procedure
could cause the engine to
overheat and be severely
damaged.
When the coolant in the coolant
recovery tank is at the FULL COLD
mark, start the vehicle.
If coolant is needed, add the proper
DEX-COOL coolant mixture at
the coolant recovery tank.
5-24 Service and Appearance Care