
GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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326 Driving and Operating
Caution (Continued)
vehicle warranty. To pull a trailer
correctly, follow the advice in this
section and see your dealer for
important information about
towing a trailer with the vehicle.
See Vehicle Load Limits 0269 for
more information about the vehicle's
maximum load capacity.
To identify the trailering capacity of
the vehicle, read the information in
“Weight of the Trailer” later in this
section.
Trailering is different than just
driving the vehicle by itself.
Trailering means changes in
handling, acceleration, braking,
durability, and fuel economy.
Successful, safe trailering takes
correct equipment, and it has to be
used properly.
The following information has many
time-tested, important trailering tips
and safety rules. Many of these are important for your safety and that of
your passengers. Read this section
carefully before pulling a trailer.
Weight of the Trailer
Safe trailering requires monitoring
the weight, speed, altitude, road
grades, outside temperature, and
how frequently the vehicle is used to
pull a trailer. Take into consideration
any special equipment on the
vehicle, and the amount of tongue
weight the vehicle can carry. See
“Weight of the Trailer Tongue”
later
in this section for more information.
Trailer weight rating (TWR) for
pickup models is calculated
assuming the tow vehicle has the
driver, a front seat passenger, and
all required trailering equipment.
Weight of additional optional
equipment, passengers, and cargo
in the tow vehicle must be
subtracted from the trailer weight
rating.
Ask your dealer for trailering
information or advice. For kingpin weight and trailer
tongue weight information, see
“Weight of the Trailer Tongue”
later
in this section.
Use the following chart to determine
how much the vehicle can weigh,
based upon the vehicle model and
options.
Weights listed apply for
conventional trailers and fifth-wheel
trailers unless otherwise noted.

GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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346 Driving and Operating
.There is a fault present in the
wiring to the trailer brakes (a
CHECK TRAILER WIRING
message will also display on
the DIC).
. The ITBC system is not working
due to a fault (a SERVICE
TRAILER BRAKE SYSTEM
message will also display in
the DIC).
Manual Trailer Brake Apply
The Manual Trailer Brake Apply
Lever is used to apply the trailer ’s
electric brakes independent of the
vehicle’s brakes. Sliding the lever to
the left will apply only the trailer
brakes. Use this lever to adjust
Trailer Gain to properly adjust the
power output to the trailer brakes.
The trailer's and the vehicle's brake
lamps will come on when either
vehicle brakes or manual trailer
brakes are applied. Trailer Gain Adjustment Procedure
Trailer Gain should be set for a
specific trailering condition and must
be adjusted anytime vehicle loading,
trailer loading, or road surface
conditions change.
{Warning
Trailer brakes that are
over-gained or under-gained may
not stop the vehicle and the trailer
as intended and can result in a
crash. Always follow the
instructions to set the Trailer Gain
for the proper trailer stopping
performance.
Use the following to adjust Trailer
Gain for each towing condition: 1. Drive the vehicle with the trailer attached on a level road
surface representative of the
towing condition and free of
traffic at about 32 to 40 km/h
(20 to 25 mph) and fully apply
the Manual Trailer Brake Apply
Lever. Adjusting Trailer Gain at
speeds lower than 32 to
40 km/h (20 to 25 mph) may
result in an incorrect gain
setting.
2. Adjust the Trailer Gain, using the Trailer Gain Adjustment
Buttons, 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.
3. Readjust Trailer Gain anytime vehicle loading, trailer loading,
or road surface conditions
change or if trailer wheel
lock-up is noticed at any time
while towing.

GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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380 Vehicle Care
Caution (Continued)
freezing occurs, which could
damage the tank if it is
completely full.
Brakes
Disc brake pads have built-in wear
indicators that make a high-pitched
warning sound when the brake pads
are worn and new pads are needed.
The sound can come and go or be
heard all the time the vehicle is
moving, except when applying the
brake pedal firmly.
{Warning
The brake wear warning sound
means that soon the brakes will
not work well. That could lead to
a crash. When the brake wear
warning sound is heard, have the
vehicle serviced.
Caution
Continuing to drive with worn-out
brake pads could result in costly
brake repair.
Some driving conditions or climates
can cause a brake squeal when the
brakes are first applied or lightly
applied. This does not mean
something is wrong with the brakes.
Properly torqued wheel nuts are
necessary to help prevent brake
pulsation. When tires are rotated,
inspect brake pads for wear and
evenly tighten wheel nuts in the
proper sequence to torque
specifications in Capacities and
Specifications 0468.
Brake linings should always be
replaced as complete axle sets.
Brake Pedal Travel
See your dealer if the brake pedal
does not return to normal height,
or if there is a rapid increase in
pedal travel. This could be a sign
that brake service may be required.
Replacing Brake System Parts
Always replace brake system parts
with new, approved replacement
parts. If this is not done, the brakes
may not work properly. The braking
performance expected can change
in many other ways if the wrong
replacement brake parts are
installed or parts are improperly
installed.
Brake Fluid
The brake master cylinder reservoir
is filled with DOT 3 brake fluid. See
Engine Compartment Overview
0 358 for the location of the
reservoir.

GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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Vehicle Care 401
for details regarding winter tire
availability and proper tire selection.
Also, seeBuying New Tires 0417.
With winter tires, there may be
decreased dry road traction,
increased road noise, and shorter
tread life. After changing to winter
tires, be alert for changes in vehicle
handling and braking.
If using winter tires:
. Use tires of the same brand and
tread type on all four wheel
positions.
. Use only radial ply tires of the
same size, load range, and
speed rating as the original
equipment tires.
Winter tires with the same speed
rating as the original equipment tires
may not be available for H, V, W, Y,
and ZR speed rated tires. If winter
tires with a lower speed rating are
chosen, never exceed the tire's
maximum speed capability.Low-Profile Tires
If the vehicle has P275/55R20,
P285/50R20, or P285/45R22
size tires, they are classified as
low-profile tires.
Caution
Low-profile tires are more
susceptible to damage from road
hazards or curb impact than
standard profile tires. Tire and/or
wheel assembly damage can
occur when coming into contact
with road hazards like potholes,
or sharp edged objects, or when
sliding into a curb. The warranty
does not cover this type of
damage. Keep tires set to the
correct inflation pressure and
when possible, avoid contact with
curbs, potholes, and other road
hazards.
All-Terrain Tires
This vehicle may have all-terrain
tires. These tires provide good
performance on most road surfaces,
weather conditions, and for off-road
driving. See Off-Road Driving 0261.
The tread pattern on these tires may
wear more quickly than other tires.
Consider rotating the tires more
frequently than at 12 000 km
(7,500 mi) intervals if irregular wear
is noted when the tires are
inspected. See Tire
Inspection 0414.
Tire Sidewall Labeling
Useful information about a tire is
molded into the sidewall. The
examples show a typical
passenger and light truck tire
sidewall.

GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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416 Vehicle Care
When installing dual wheels,
check that the vent holes in the
inner and outer wheels on each
side are lined up.
Adjust the front and rear tires to
the recommended inflation
pressure on the Tire and
Loading Information label after
the tires have been rotated. See
Tire Pressure0408 and Vehicle
Load Limits 0269.
Check that all wheel nuts are
properly tightened. See “Wheel
Nut Torque” underCapacities
and Specifications 0468.
{Warning
Rust or dirt on a wheel, or on the
parts to which it is fastened, can
make wheel nuts become loose
after time. The wheel could come
off and cause an accident. When
changing a wheel, remove any
rust or dirt from places where the
wheel attaches to the vehicle. In
(Continued)
Warning (Continued)
an emergency, a cloth or a paper
towel can be used; however, use
a scraper or wire brush later to
remove all rust or dirt.
Lightly coat the inner diameter of
the wheel hub opening with
wheel bearing grease after a
wheel change or tire rotation to
prevent corrosion or rust
build-up. Do not get grease on
the flat wheel mounting surface
or on the wheel nuts or bolts.
Reset the Tire Pressure Monitor
System (TPMS), if the vehicle
has one. SeeTire Pressure
Monitor Operation 0410.
Check that the spare tire, if the
vehicle has one, is stored
properly. Push, pull, and then try
to rotate or turn the tire. If it
moves, tighten the cable. See “Storing a Flat or Spare Tire and
Tools”
underTire
Changing 0424.
When It Is Time for New
Tires
Factors, such as maintenance,
temperatures, driving speeds,
vehicle loading, and road conditions
affect the wear rate of the tires.
Treadwear indicators are one way to
tell when it is time for new tires.
Treadwear indicators appear when
the tires have only 1.6 mm (1/16 in)
or less of tread remaining. Some
commercial truck tires may not have

GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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Vehicle Care 423
If a Tire Goes Flat
It is unusual for a tire to blowout
while driving, especially if the tires
are maintained properly. If air goes
out of a tire, it is much more likely to
leak out slowly. But if there ever is a
blowout, here are a few tips about
what to expect and what to do:
If a front tire fails, the flat tire
creates a drag that pulls the vehicle
toward that side. Take your foot off
the accelerator pedal and grip the
steering wheel firmly. Steer to
maintain lane position, and then
gently brake to a stop, well off the
road, if possible.
A rear blowout, particularly on a
curve, acts much like a skid and
may require the same correction as
used in a skid. Stop pressing the
accelerator pedal and steer to
straighten the vehicle. It may be
very bumpy and noisy. Gently brake
to a stop, well off the road,
if possible.{Warning
Driving on a flat tire will cause
permanent damage to the tire.
Re-inflating a tire after it has been
driven on while severely
underinflated or flat may cause a
blowout and a serious crash.
Never attempt to re-inflate a tire
that has been driven on while
severely underinflated or flat.
Have your dealer or an authorized
tire service center repair or
replace the flat tire as soon as
possible.
{Warning
Lifting a vehicle and getting under
it to do maintenance or repairs is
dangerous without the
appropriate safety equipment and
training. If a jack is provided with
the vehicle, it is designed only for
changing a flat tire. If it is used for
anything else, you or others could(Continued)
Warning (Continued)
be badly injured or killed if the
vehicle slips off the jack. If a jack
is provided with the vehicle, only
use it for changing a flat tire.
If a tire goes flat, avoid further tire
and wheel damage by driving slowly
to a level place, well off the road,
if possible. Turn on the hazard
warning flashers. See Hazard
Warning Flashers 0178.
{Warning
Changing a tire can be
dangerous. The vehicle can slip
off the jack and roll over or fall
causing injury or death. Find a
level place to change the tire. To
help prevent the vehicle from
moving:
1. Set the parking brake firmly. (Continued)

GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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424 Vehicle Care
Warning (Continued)
2. Put an automatictransmission in P (Park) or a
manual transmission in
1 (First) or R (Reverse).
3. For four-wheel-drive vehicles, be sure the
transfer case is in a drive
gear– not in N (Neutral).
4. Turn off the engine and do not restart while the vehicle
is raised.
5. Do not allow passengers to remain in the vehicle.
6. Place wheel blocks, if equipped, on both sides of
the tire at the opposite
corner of the tire being
changed.
When the vehicle has a flat tire (2),
use the following example as a
guide to assist in the placement of
the wheel blocks (1), if equipped.
1. Wheel Block (If Equipped)
2. Flat Tire
The following information explains
how to use the jack and change
a tire.
Tire Changing
Removing the Spare Tire and
Tools
Crew Cab
1. Wheel Blocks
2. Wing Nut Retaining Wheel Blocks
3. Tool Kit
4. Wing Nut Retaining Tool Kit
5. Jack
6. Jack Knob

GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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460 Service and Maintenance
(3)Or every four years, whichever
comes first. If driving in dusty
conditions, inspect the filter at each
oil change or more often as needed.
(4) Do not directly power wash the
transfer case and/or front/rear axle
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/or axles
and should be replaced.
(5) Or every five years, whichever
comes first. See Cooling
System 0371.
(6) Or every 10 years, whichever
comes first. Inspect for fraying,
excessive cracking, or damage;
replace, if needed.
(7) Replace brake fluid every five
years. See Brake Fluid 0380.Special Application
Services
.
Vehicles with Dual Wheels:
Check dual wheel nut torque at
160, 1 600 and 10 000 km (100,
1,000 and 6,000 mi) of driving.
Repeat this service whenever a
tire/wheel is serviced or
removed.
. Severe Commercial Use
Vehicles Only: Lubricate chassis
components every 5 000 km/
3,000 mi.
. Have underbody flushing service
performed. See “Underbody
Maintenance” inExterior
Care 0444.
Additional
Maintenance and Care
Your vehicle is an important
investment and caring for it properly
may help to avoid future costly
repairs. To maintain vehicle
performance, additional
maintenance services may be
required.
It is recommended that your dealer
perform these services —their
trained dealer technicians know
your vehicle best. Your dealer can
also perform a thorough
assessment with a multi-point
inspection to recommend when your
vehicle may need attention.
The following list is intended to
explain the services and conditions
to look for that may indicate
services are required.
Battery
The 12-volt battery supplies power
to start the engine and operate any
additional electrical accessories.