towing CHEVROLET SUBURBAN 2009 Service Manual

SERVICE TRAILER BRAKE SYSTEM – This message
will be displayed when there is a problem with the
ITBC system. If this message persists over multiple
ignition cycles there is problem with the ITBC system.
Take the vehicle to an authorized dealer/retailer to have
the ITBC system diagnosed and repaired.
If either the CHECK TRAILER WIRING or SERVICE
TRAILER BRAKE SYSTEM message is displayed while
driving the vehicle, power is no longer available to the
trailer brakes. When traffic conditions allow, carefully
pull the vehicle over to the side of the road and turn the
ignition off. Check the wiring connection to the trailer and
turn the ignition back on. If either of these messages
continues, either the vehicle or trailer needs service.
An authorized dealer/retailer may be able to diagnose
and repair problems with the trailer. However, any
diagnosis and repair of the trailer is not covered under
the vehicle warranty. Please contact your trailer dealer
for assistance with trailer repairs and trailer warranty
information.Driving with a Trailer
{CAUTION:
When towing a trailer, exhaust gases may collect
at the rear of the vehicle and enter if the liftgate,
trunk/hatch, or rear-most window is open.
Engine exhaust contains carbon monoxide (CO)
which cannot be seen or smelled. It can cause
unconsciousness and even death.
To maximize safety when towing a trailer:
Have the exhaust system inspected for
leaks and make necessary repairs before
starting a trip.
Never drive with the liftgate, trunk/hatch, or
rear-most window open.
Fully open the air outlets on or under the
instrument panel.
Adjust the Climate Control system to a setting
that brings in only outside air and set the fan
speed to the highest setting. See Climate
Control System in the Index.
For more information about carbon monoxide, see
Engine Exhaust on page 2-50.
4-66

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.
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 will not strike soft
shoulders, curbs, road signs, trees or other objects.
Avoid jerky or sudden maneuvers. Signal well in
advance.
4-67

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 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.
The tow/haul mode may be used if the transmission
shifts too often. SeeTow/Haul Mode Light on page 3-49.
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. If the overheat warning
comes on, seeEngine Overheating on page 5-35.
4-68

Leaving After Parking on a Hill
1. Apply and hold the brake pedal while you:
Start the engine
Shift into a gear
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
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
The vehicle is equipped with the following wiring
harnesses for towing a trailer.
Basic Trailer Wiring
The trailer wiring harness, with a seven-pin connector,
is located at the rear of the vehicle and is tied to the
vehicle’s frame. The harness connector can be plugged
into a seven-pin universal heavy-duty trailer connector
available through your dealer/retailer.
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: Battery Feed*
Dark Blue: Trailer Brake*
*The fuses for these two circuits are installed in the
underhood electrical center, but the wires are not
connected. They should be connected by your
dealer/retailer or a qualied service center.
4-70

Heavy-Duty Trailer Wiring Harness
Package
The 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: Battery Feed*
Dark Blue: Trailer Brake*
*The fuses for these two circuits are installed in the
underhood electrical center, but the wires are not
connected. They should be connected by your
dealer/retailer or a qualied service center.
If charging a remote (non-vehicle) battery, press the
Tow/Haul mode button, if equipped, located at the end of
the shift lever. This will boost the vehicle system voltage
and properly charge the battery. If the trailer is too light
for Tow/Haul mode, or the vehicle is not equipped with
Tow/Haul, turn on the headlamps as a second way to
boost the vehicle system and charge the battery.
4-71

Electric Brake Control Wiring
Provisions
These wiring provisions are included with the 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.
If the vehicle is equipped with an ITBC, the blunt cuts
exist, but are not connected further in the harness.
If an aftermarket trailer brake controller is installed,
the ITBC must be disconnected. Do not power
both ITBC and aftermarket controllers to control
the trailer brakes at the same time.
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 4-50.
4-72

If Steam Is Coming From The Engine
Compartment
{CAUTION:
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. 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 the vehicles engine is
overheated, the liquids in it can catch re. You or
others could be badly burned. Stop the engine if it
overheats, and get out of the vehicle until the
engine is cool.
SeeOverheated Engine Protection Operating Mode
on page 5-37for information on driving to a safe
place in an emergency.
If No Steam Is Coming From The
Engine Compartment
The ENGINE OVERHEATED STOP ENGINE or the
ENGINE OVERHEATED IDLE ENGINE message, along
with a low coolant condition, can indicate a serious
problem.
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. SeeTowing a Trailer on page 4-50.
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.
5-36

If the temperature overheat gage 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.
Also, see “Overheated Engine Protection Operating
Mode” later in this section.
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 the 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 5-15.
Engine Fan Noise
If the 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.
5-37

If the 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 the 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.
Power Steering Fluid
If the vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
SeeEngine Compartment
Overview on page 5-14for
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.
How to Check Power Steering Fluid
To check the power steering uid:
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. Remove the cap again and look at the uid level on
the dipstick.
The level should be at the FULL COLD mark.
If necessary, add only enough uid to bring the
level up to the mark.
5-38

(f)Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
rear compartment hinges, outer liftgate handle pivot
points, rear door detent link, roller mechanism, liftgate
handle pivot points, latch bolt, fuel door hinge, cargo
door hinge, locks, and folding seat hardware. More
frequent lubrication may be required when exposed to
a corrosive environment. Applying silicone grease
on weatherstrips with a clean cloth will make them
last longer, seal better, and not stick or squeak.
(g)Check vent hose at transfer case for kinks and
proper installation. Check to be sure vent hose is
unobstructed, clear, and free of debris. During any
maintenance, if a power washer is used to clean mud
and dirt from the underbody, care should be taken to
not directly spray the transfer case output seals. High
pressure water can overcome the seals and contaminate
the transfer case fluid. Contaminated fluid will decrease
the life of the transfer case and should be replaced.
(h)Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.When doing frequent trailer towing.
Uses such as found in taxi, police, or delivery
service.
(i)Drain, flush, and refill cooling system. This service
can be complex; you should have your dealer/retailer
perform this service. See Engine Coolant on page 5-29
for what to use. Inspect hoses. Clean radiator,
condenser, pressure cap, and filler neck. Pressure
test the cooling system and pressure cap.
(j)A fluid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the fluid level checked. Add fluid if needed.
(k)Inspect system. Check all fuel and vapor lines
and hoses for proper hook-up, routing, and condition.
Check that the purge valve works properly, if equipped.
Replace as needed.
(l)If driving regularly under dusty conditions, inspect the
filter at each engine oil change.
(m)Visually inspect belt for fraying, excessive cracks, or
obvious damage. Replace belt if necessary.
(n)Severe Service: Change transfer case fluid if the
vehicle is mainly used for trailer towing or driven in city
traffic, wet environment, or high ambient temperatures.
6-9