2010 GMC SIERRA towing

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.
If the trailer turn signal bulbs burn out, the arrows on the
instrument panel will still flash for turns. 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 beforestarting
down a long or steep downgrade. If the transmission is
not shifted down, the brakes might 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. See Tow/Haul Mode on page 3‑34. 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 6‑34.
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. Turn the wheels into the curb if facing downhill
or into traffic if facing uphill.
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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.
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.
Heavy-DutyTrailer Wiring Harness
Package
For vehicles equipped with heavy duty trailering, the
harness is connected 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*
5-74

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 has this
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 figure 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 see Towing a Trailer
on
page 5‑50.
5-77

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 5‑50.
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
five 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
REDUCED ENGINE POWER message is displayed, an
overheat protection mode which alternates firing 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.
6-36

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. See Engine Oil
on
page 6‑18.
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.
Power Steering Fluid
See
Engine Compartment
Overviewon page 6‑16for reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering
fluid unless you suspect there is a leak in the system or
you hear an unusual noise. A fluid loss in this system
could indicate a problem. Have the system inspected
and repaired.
6-37

First Engine Oil Change After Every
80 000 km/50,000 Miles
.Engine air cleaner filter replacement. SeeEngine
Air Cleaner/Filter on page 6‑21.
.Automatic transmission fluid change (severe
service) for vehicles with Gross Vehicle Weight
Rating (GVWR) over 3 901 kg (8,600 lbs) or mainly
driven in heavy city traffic in hot weather, in hilly or
mountainous terrain, when frequently towing a
trailer, or used for taxi, police, or delivery service.
See Automatic Transmission Fluid (4-Speed
Transmission)
on page 6‑23or Automatic
Transmission Fluid (6-Speed Transmission)on
page 6‑26.
.Four‐wheel drive only: Transfer case fluid change
(severe service) for vehicles mainly driven when
frequently towing a trailer, or used for taxi, police,
or delivery service. 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.
.Evaporative control system inspection. 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.
An Emission Control Service. The U.S.
Environmental Protection Agency or the California
Air Resources Board has determined that the
failure to perform this maintenance item will not
nullify the emission warranty or limit recall liability
prior to the completion of the vehicle's useful life.
We, however, urge that all recommended
maintenance services be performed at the
indicated intervals and the maintenance be
recorded.
7-7

Services Provided
.Emergency Fuel Delivery:Delivery of enough
fuel for the vehicle to get to the nearest service
station.
.Lock‐Out Service: Service is provided to unlock
the vehicle if you are locked out. A remote unlock
may be available if you have OnStar
®. For security
reasons, the driver must present identification
before this service is given.
.Emergency Tow From a Public Road or
Highway: Tow to the nearest GMC dealer for
warranty service, or if the vehicle was in a crash
and cannot be driven. Assistance is also given
when the vehicle is stuck in the sand, mud,
or snow.
.Flat Tire Change: Service is provided to change
a flat tire with the spare tire. The spare tire,
if equipped, must be in good condition and
properly inflated. It is the owner's responsibility for
the repair or replacement of the tire if it is not
covered by the warranty.
.Battery Jump Start: Service is provided to jump
start a dead battery.
.Trip Routing Service: Detailed maps of North
America are provided when requested either with
the most direct route or the most scenic route.
Additional travel information is also available.
Allow three weeks for delivery.
.Trip Interruption Benefits and Assistance:
If your trip is interrupted due to a warranty failure,
incidental expenses may be reimbursed during the
5 years/100,000 miles (160 000 km) Powertrain
warranty period. Items considered are hotel,
meals, and rental car.
Services Not Included in Roadside
Assistance
.Impound towing caused by violation of any laws.
.Legal fines.
.Mounting, dismounting or changing of snow tires,
chains, or other traction devices.
.Towing or services for vehicles driven on a
non-public road or highway.
8-9

If a Crash Occurs
Here is what to do if you are involved in a crash.
.Check to make sure that you are all right. If you
are uninjured, make sure that no one else in your
vehicle, or the other vehicle, is injured.
.If there has been an injury, call emergency
services for help. Do not leave the scene of a
crash until all matters have been taken care of.
Move your vehicle only if its position puts you in
danger or you are instructed to move it by a police
officer.
.Give only the necessary and requested information
to police and other parties involved in the crash.
Do not discuss your personal condition, mental
frame of mind, or anything unrelated to the crash.
This will help guard against post-crash legal action.
.If you need roadside assistance, call GM Roadside
Assistance. SeeRoadside Assistance Programon
page 8‑7for more information.
.If your vehicle cannot be driven, know where the
towing service will be taking it. Get a card from the
tow truck operator or write down the driver's name,
the service's name, and the phone number.
.Remove any valuables from your vehicle before it
is towed away. Make sure this includes your
insurance information and registration if you keep
these items in your vehicle.
.Gather the important information you will need from
the other driver. Things like name, address, phone
number, driver's license number, vehicle license
plate, vehicle make, model and model year,
Vehicle Identification Number (VIN), insurance
company and policy number, and a general
description of the damage to the other vehicle.
.If possible, call your insurance company from the
scene of the crash. They will walk you through the
information they will need. If they ask for a police
report, phone or go to the police department
headquarters the next day and you can get a copy
of the report for a nominal fee. In some states/
provinces with “no fault”insurance laws, a report
may not be necessary. This is especially true if
there are no injuries and both vehicles are
driveable.
.Choose a reputable collision repair facility for your
vehicle. Whether you select a dealer/retailer or a
private collision repair facility to fix the damage,
make sure you are comfortable with them.
Remember, you will have to feel comfortable with
their work for a long time.
.Once you have an estimate, read it carefully and
make sure you understand what work will be
performed on your vehicle. If you have a question,
ask for an explanation. Reputable shops welcome
this opportunity.
8-14