towing CHEVROLET SILVERADO 2009 2.G Service Manual

The ITBC system is integrated with the vehicle’s brake,
anti-lock brake and StabiliTrak (if equipped) systems.
In trailering conditions that cause the vehicle’s anti-lock
brake or StabiliTrak systems to activate, power sent
to the trailer’s brakes will be automatically adjusted to
minimize trailer wheel lock-up. This does not imply
that the trailer has the StabiliTrak system.
If the vehicle’s brake, anti-lock brake or StabiliTrak
systems are not functioning properly, the ITBC system
may not be fully functional or may not function at
all. Make sure all of these systems are fully operational
to ensure full functionality of the ITBC system.
The ITBC system is powered through the vehicle’s
electrical system. Turning the ignition off will also turn
off the ITBC system. The ITBC system is fully functional
only when the ignition is in ON or in RUN.
The ITBC system can only be used with trailers with
electric brakes.
{CAUTION:
Connecting a trailer that is not compatible with the
ITBC system may result in reduced or complete
loss of trailer braking. There may be an increase in
stopping distance or trailer instability which could
result in personal injury or damage to the vehicle,
trailer, or other property. An aftermarket controller
may be available for use with trailers with surge, air
or electric-over-hydraulic trailer brake systems. To
determine the type of brakes on the trailer and the
availability of controllers, check with your trailer
manufacturer or dealer/retailer.
When trailering, make sure of the following:
The ITBC system is used only with trailers that are
equipped with electric brakes.
All applicable local and federal laws and regulations
are followed.
All electrical and mechanical connections to the
trailer are made correctly.
The trailer’s brakes are in proper working condition.
The trailer and vehicle are properly loaded for
the towing condition.
4-70

Trailer Gain Adjustment Procedure
Trailer Gain should be set for a specic trailering
condition and must be adjusted any time vehicle loading,
trailer loading or road surface conditions change.
Setting the Trailer Gain properly is needed for the
best trailer stopping performance. A trailer that is
over-gained may result in locked trailer brakes. A trailer
that is under-gained may result in not enough trailer
braking. Both of these conditions may result in poorer
stopping and stability of the vehicle and trailer.
Use the following procedure to correctly adjust Trailer
Gain for each towing condition:
1. Make sure the trailer brakes are in proper working
condition.
2. Connect a properly loaded trailer to the vehicle and
make all necessary mechanical and electrical
connections. SeeLoading the Vehicle on page 4-32
for more information.
3. After the electrical connection is made to a trailer
equipped with electric brakes:
A TRAILER CONNECTED message will be
briey displayed on the DIC display.
The Trailer Brake Display Page will appear on
the DIC showing TRAILER GAIN and TRAILER
OUTPUT.
In the Trailer Output display on the DIC,
“------’’will disappear if there is no error
present. Connecting a trailer without electric
brakes will not clear the six dashed lines.
4. Adjust the Trailer Gain by using the gain adjustment
(+ / -) buttons on the Trailer Brake Control Panel.
5. Drive the vehicle with the trailer attached on a level
road surface representative of the towing condition
and free of traffic at about 20 to 25 mph (32 to
40 km/h) and fully apply the Manual Trailer Brake
Apply lever.
Adjusting trailer gain at speeds lower than 20 to
25 mph (32 to 40 km/h) may result in an incorrect
gain setting.
6. Adjust the Trailer Gain to just below the point of
trailer wheel lock-up, indicated by trailer wheel
squeal or tire smoke when a trailer wheel locks.
Trailer wheel lock-up may not occur if towing
a heavily loaded trailer. In this case, adjust the
Trailer Gain to the highest allowable setting for the
towing condition.
7. Re-adjust Trailer Gain any time vehicle loading,
trailer loading or road surface conditions change
or if trailer wheel lock-up is noticed at any time while
towing.
4-74

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 GM dealer 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 2-55.
4-76

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.
While towing a trailer or when exposed to long periods
of sunshine, the oor of the truck bed may become
very warm. Avoid putting items in the truck bed
that might be affected by high ambient temperatures.
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.
4-77

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 3-51.
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, see
Engine Overheating on page 5-34.
4-78

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 one of the following wiring
harnesses for towing a trailer or hauling a slide-in
camper.
Basic Trailer Wiring
All regular, extended cab and crew cab pickups have a
seven-wire trailer towing harness.
For vehicles not equipped with heavy duty trailering, the
harness is secured to the vehicle’s frame behind the
spare tire mount. The harness requires the installation of
a trailer connector, which is available through your
dealer/retailer.
If towing a light-duty trailer with a standard four-way
round pin connector, an adapter is available from your
dealer/retailer.
4-80

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 behind the steering column
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.
Auxiliary Battery
The auxiliary battery provision can be used to supply
electrical power to additional equipment that may
be added, such as a slide-in camper. If the vehicle hasthis provision, this relay will be located on the drivers
side of the vehicle, next to the underhood electrical
center.
Be sure to follow the proper installation instructions that
are included with any electrical equipment that is installed.
Notice:Leaving electrical equipment on for
extended periods will drain the battery. Always turn
off electrical equipment when not in use and do not
use equipment that exceeds the maximum amperage
rating for the auxiliary battery provision.
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 4-51.
4-83

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 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. SeeTowing a Trailer on page 4-51.If you get the ENGINE OVERHEATED STOP ENGINE or
the ENGINE OVERHEATED IDLE ENGINE message
with no sign of steam, try this for a minute or so:
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. If you are stopped in a traffic jam, apply the brake,
shift to N (Neutral); otherwise, shift to the highest
gear while driving—D(Drive) or 3 (Third).
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
ve 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.
5-36

Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
REDUCED ENGINE POWER 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.
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.
5-37

(f)Lubricate all key lock cylinders, body door hinges,
hood latch assembly, secondary latch, pivots, spring
anchor, release pawl, tailgate hinges, tailgate linkage,
tailgate handle pivot points, latch bolt, fuel 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 Gross Vehicle Weight Rating (GVWR) is over
8600 lbs or 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, if the vehicle has one, works
properly. Replace as needed.
(l)Extreme Duty Service: Change transfer case fluid if
the vehicle is mainly driven off-road in four-wheel
drive. Vehicles used for farming, mining, forestry,
Department of Natural Resources (DNR), and snow
plowing occupations meet this definition.
(m)Severe Duty Service: Change transfer case fluid if
the vehicle is mainly driven under one or more of
these conditions:
Frequent trailer towing.
Taxi, police, or delivery service.
6-10