2008 GMC SIERRA towing

If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle immediately.
If there is still no sign of steam and your vehicle has an
engine-driven cooling fan, push down the accelerator
until the engine speed is about twice as fast as normal
idle speed for at least ve minutes while you
are parked.
If there is still no sign of steam and your vehicle has an
electric cooling fan, idle the engine for ve minutes
while you are parked.
If you still have the warning, turn off the engine and get
everyone out of the vehicle until it cools down. Also,
see “Overheated Engine Protection Operating Mode”
later in this section.
You may decide not to lift the hood but to get service
help right away.Overheated Engine Protection
Operating Mode (V8 Engines Only)
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 your 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
(Gasoline Engine) on page 5-15.
5-33

Engine Fan Noise
If your 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 your 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 your 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
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.
5-39

(e)Make sure the safety belt reminder light and safety
belt assemblies are working properly. Look for any
other loose or damaged safety belt system parts. If you
see anything that might keep a safety belt system
from doing its job, have it repaired. Have any torn or
frayed safety belts replaced. Also see Checking
the Restraint Systems on page 1-87.
(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.(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 5-28for what to
use. Inspect hoses. Clean radiator, condenser, pressure
cap, and ller 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.
6-10

(l)Extreme Duty Service: Change transfer case fluid if
the vehicle is mainly driven off-road in four-wheel
drive, or is used for heavy trailer towing. Farming,
mining, forestry, and Department of Natural Resources
(DNR) vehicles meet this definition.
(m)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.
(n)Vehicles with diesel engine or with GVWR above
10,000 lbs (4 536 kg) only: Inspect shields for damage or
looseness. Adjust or replace as required. This is a
Noise Emission Control Service. Applicable to vehicles
sold in the United States and recommended for
vehicles sold in Canada.
(p)If you drive regularly under dusty conditions, inspect
the filter or change indicator (if equipped) at each
engine oil change.
(q)Visually inspect belt for fraying, excessive cracks, or
obvious damage. Replace belt if necessary.Owner Checks and Services
These owner checks and services should be performed
at the intervals specied to help ensure the safety,
dependability, and emission control performance of your
vehicle. Your dealer/retailer can assist you with these
checks and services.
Be sure any necessary repairs are completed at once.
Whenever any uids or lubricants are added to your
vehicle, make sure they are the proper ones, as shown
inRecommended Fluids and Lubricants on page 6-15.
At the First 100, 1,000 and 6,000
Miles (160, 1 600 and 10 000 km)
For vehicles with dual wheels, check dual wheel
nut torque. For proper torque, seeCapacities and
Specifications on page 5-130.
At Each Fuel Fill
It is important to perform these underhood checks at
each fuel fill.
6-11

Towing and Road Service Exclusions
Specically excluded from Roadside Assistance
coverage are towing or services for vehicles operated on
a non-public roadway or highway, nes, impound towing
caused by a violation of local, Municipal, State,
Provincial, or Federal law, and mounting, dismounting or
changing of snow tires, chains, or other traction devices.
Roadside Assistance is not part of or included in the
coverage provided by the New Vehicle Limited Warranty.
GMC and General Motors of Canada Limited reserve
the right to make any changes or discontinue the
Roadside Assistance program at any time without
notication.
Scheduling Service Appointments
When your vehicle requires warranty service, contact
your dealer/retailer and request an appointment.
By scheduling a service appointment and advising your
service consultant of your transportation needs, your
dealer/retailer can help minimize your inconvenience.
If your vehicle cannot be scheduled into the service
department immediately, keep driving it until it can be
scheduled for service, unless, of course, the problem is
safety-related. If it is, please call your dealership/retailer,
let them know this, and ask for instructions.If the dealer/retailer requests that you simply drop the
vehicle off for service, you are urged to do so as early in
the work day as possible to allow for the same day repair.
Courtesy Transportation
To enhance your ownership experience, we and our
participating dealers are proud to offer Courtesy
Transportation, a customer support program for vehicles
with the Bumper to Bumper (Base Warranty Coverage
period in Canada) and extended powertrain warranty
in both the U.S. and Canada.
Several courtesy transportation options are available to
assist in reducing your inconvenience when warranty
repairs are required.
Courtesy Transportation is not a part of the New Vehicle
Limited Warranty. A separate booklet entitled “Warranty
and Owner Assistance Information” furnished with each
new vehicle provides detailed warranty coverage
information.
7-9

If you need roadside assistance, call GM Roadside
Assistance. SeeRoadside Assistance Program on
page 7-7for 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
Identication 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 x 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.
7-13

Rearview Mirror, Automatic Dimming with
Compass and Temperature Display................2-57
Rearview Mirror, Automatic Dimming with OnStar
®,
Compass and Temperature Display..................2-55
Rearview Mirrors.............................................2-55
Reclining Seatbacks.......................................... 1-8
Recommended Fluids and Lubricants.................6-15
Recovery Hooks.............................................4-35
Recreational Vehicle Towing.............................4-50
Remote Keyless Entry (RKE) System.................. 2-4
Remote Keyless Entry (RKE) System, Operation.... 2-5
Remote Vehicle Start........................................ 2-7
Removing the Flat Tire and Installing the
Spare Tire..................................................5-98
Removing the Spare Tire and Tools...................5-93
Replacement Bulbs.........................................5-65
Replacement Parts, Maintenance......................6-17
Reporting Safety Defects
Canadian Government..................................7-15
General Motors...........................................7-15
United States Government............................7-14
Restraint System Check
Checking the Restraint Systems....................1-87
Replacing Restraint System Parts After
a Crash..................................................1-88
Retained Accessory Power (RAP)......................2-23
Roadside
Assistance Program....................................... 7-7
Rocking Your Vehicle to Get it Out....................4-34Routing, Engine Drive Belt...............................6-18
Running the Engine While Parked.....................2-54
SSafety Belt
Reminder Light............................................3-37
Safety Belts
Care of....................................................5-115
How to Wear Safety Belts Properly................1-19
Lap Belt.....................................................1-34
Lap-Shoulder Belt........................................1-28
Safety Belt Extender....................................1-35
Safety Belt Use During Pregnancy.................1-33
Safety Belts Are for Everyone.......................1-14
Safety Warnings and Symbols.............................. iii
Scheduled Maintenance..................................... 6-4
Seatback Latches...........................................1-11
Seats
Center Seat................................................1-12
Head Restraints..........................................1-10
Heated Seats............................................... 1-6
Manual Lumbar............................................. 1-5
Memory, Mirrors and Pedals........................... 1-6
Power Lumbar.............................................. 1-5
Power Seats................................................. 1-4
Rear Seat Operation............................1-12, 1-13
Reclining Seatbacks...................................... 1-8
Seatback Latches........................................1-11
11

Tilt Wheel........................................................ 3-9
Time, Setting..................................................3-81
Tire
Pressure Light.............................................3-47
Tires.............................................................5-66
Aluminum or Chrome-Plated Wheels,
Cleaning...............................................5-118
Buying New Tires........................................5-84
Chains.......................................................5-90
Changing a Flat Tire....................................5-92
Cleaning...................................................5-119
Different Size..............................................5-86
Dual Tire Operation.....................................5-76
If a Tire Goes Flat.......................................5-91
Ination - Tire Pressure................................5-74
Inspection and Rotation................................5-81
Installing the Spare Tire................................5-98
Pressure Monitor Operation...........................5-78
Pressure Monitor System..............................5-76
Removing the Flat Tire.................................5-98
Removing the Spare Tire and Tools...............5-93
Secondary Latch System............................5-105
Spare Tire................................................5-112
Storing a Flat or Spare Tire and Tools..........5-108
Tire Sidewall Labeling..................................5-67
Tire Terminology and Denitions....................5-71
Uniform Tire Quality Grading.........................5-86
Wheel Alignment and Tire Balance.................5-88Tires (cont.)
Wheel Replacement.....................................5-88
When It Is Time for New Tires......................5-84
Tow/Haul Mode...............................................2-34
Tow/Haul Mode Light.......................................3-53
Towing
Recreational Vehicle.....................................4-50
Towing a Trailer..........................................4-55
Your Vehicle...............................................
4-50
Traction
StabiliTrak
®System....................................... 4-6
Trailer
Recommendations.......................................4-94
Transmission
Fluid, Automatic..................................5-22, 5-25
Transmission Operation, Automatic....................2-28
Trip Odometer................................................3-36
Truck-Camper Loading Information....................4-47
Turn and Lane-Change Signals.........................3-10
Turn Signal/Multifunction Lever........................... 3-9
U
Ultrasonic Rear Parking Assist (URPA)...............2-63
Uniform Tire Quality Grading............................5-86
Universal Home Remote System.......................2-68
Operation...................................................2-69
Using this Manual............................................... iii
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