brake light GMC SIERRA 1500 2012 Owner's Guide

Black plate (99,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-99
.When pulling a heavy trailer
or a large or heavy load in
stop-and-go traffic.
.When pulling a heavy trailer or
a large or heavy load in busy
parking lots where improved low
speed control of the vehicle is
desired.
Operating the vehicle in Tow/Haul
when lightly loaded or with no
trailer at all will not cause damage.
However, there is no benefit to the
selection of Tow/Haul when the
vehicle is unloaded. Such a
selection when unloaded may
result in unpleasant engine and
transmission driving characteristics
and reduced fuel economy. Tow/
Haul is recommended only when
pulling a heavy trailer or a large or
heavy load.
Integrated Trailer Brake
Control System
The vehicle may have an Integrated
Trailer Brake Control (ITBC) system
for electric trailer brakes.
This symbol is located on the Trailer
Brake Control Panel on vehicles
with an Integrated Trailer Brake
Control system. The power output to
the trailer brakes is based on the
amount of brake pressure being
applied by the vehicle’s brake
system. This available power
output to the trailer brakes can be
adjusted to a wide range of trailering
situations. The ITBC system is integrated
with the vehicle’s brake, antilock
brake, and StabiliTrak (if equipped)
systems. In trailering conditions that
cause the vehicle’s antilock 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
StabiliTrak.
Non-hybrid vehicles with StabiliTrak
have a Trailer Sway Control (TSC)
feature. See
Trailer Sway Control
(TSC) on page 9‑105.
Non-hybrid vehicles with StabiliTrak
have a Hill Start Assist (HSA)
feature. See Hill Start Assist (HSA)
on page 9‑54.

Black plate (105,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-105
vehicle to an authorized GM dealer
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 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.Trailer Sway
Control (TSC)
Non-hybrid vehicles with StabiliTrak
have a Trailer Sway Control (TSC)
feature. If the vehicle is towing a
trailer and the system detects
that the trailer is swaying, the
vehicle brakes are applied without
the driver pressing the brake
pedal. If the vehicle is equipped with
the Integrated Trailer Brake Control
(ITBC) system, StabiliTrak may also
apply the trailer brakes. The TCS/
StabiliTrak warning light will flash on
the instrument panel cluster to notify
the driver to reduce speed. If the
trailer continues to sway, StabiliTrak
will reduce engine torque to help
slow the vehicle. SeeStabiliTrak
®
System on page 9‑55 for more
information.
Adding non‐dealer accessories can
affect the vehicle performance. See
Accessories and Modifications on
page 10‑3 for more information.
Conversions and
Add-Ons
Add-On Electrical
Equipment
Notice:Do not add anything
electrical to the vehicle unless
you check with your dealer first.
Some electrical equipment can
damage the vehicle and the
damage would not be covered
by the vehicle's warranty. Some
add-on electrical equipment can
keep other components from
working as they should.
Add-on equipment can drain the
vehicle's 12‐volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle on page 3‑36 andAdding
Equipment to the Airbag-Equipped
Vehicle on page 3‑37.

Black plate (27,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-27
Brakes
This vehicle has front disc brakes
and could have rear drum brakes or
rear disc 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.
Notice: 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 on page 12‑2.
If the vehicle has rear drum brakes,
they do not have wear indicators,
but if a rear brake rubbing noise is
heard, have the rear brake linings
inspected immediately. Rear brake
drums should be removed and
inspected each time the tires are
removed for rotation or changing.
Drum brakes have an inspection
hole to inspect lining wear during
scheduled maintenance. When the
front brake pads are replaced, have
the rear brakes inspected, too. 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 might be
required.
Brake Adjustment
Every time the brakes are applied,
with or without the vehicle moving,
the brakes adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is
complex. Its many parts have to be
of top quality and work well together
if the vehicle is to have really good
braking. The vehicle was designed
and tested with top-quality brake
parts. When parts of the braking
system are replaced, be sure to get
new, approved replacement parts.

Black plate (28,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-28 Vehicle Care
If this is not done, the brakes might
not work properly. For example,
installing disc brake pads that are
wrong for the vehicle, can change
the balance between the front and
rear brakes—for the worse. The
braking performance expected can
change in many other ways if the
wrong replacement brake parts are
installed.
Brake Fluid
The brake master cylinder reservoir
is filled with DOT 3 brake fluid. See
Engine Compartment Overview on
page 10‑6 for the location of the
reservoir. There are only two reasons why the
brake fluid level in the reservoir
might go down:
.The brake fluid level goes down
because of normal brake lining
wear. When new linings are
installed, the fluid level goes
back up.
.A fluid leak in the brake
hydraulic system can also cause
a low fluid level. Have the brake
hydraulic system fixed, since a
leak means that sooner or later
the brakes will not work well.
Do not top off the brake fluid.
Adding fluid does not correct a leak.
If fluid is added when the linings
are worn, there will be too much
fluid when new brake linings are
installed. Add or remove brake fluid,
as necessary, only when work is
done on the brake hydraulic system.
{WARNING
If too much brake fluid is added, it
can spill on the engine and burn,
if the engine is hot enough. You
or others could be burned, and
the vehicle could be damaged.
Add brake fluid only when work
is done on the brake hydraulic
system. See “Checking Brake
Fluid” in this section.
When the brake fluid falls to a low
level, the brake warning light comes
on. See Brake System Warning
Light on page 5‑25.
Refer to the Maintenance Schedule
to determine when to check the
brake fluid. See Maintenance
Schedule on page 11‑3.

Black plate (55,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-55
Light Truck (LT‐Metric) Tire
(A) Light Truck (LT‐Metric)
Tire
:The United States version
of a metric tire sizing system.
The letters LT as the first two
characters in the tire size mean
a light truck tire engineered to
standards set by the U.S. Tire
and Rim Association.
(B) Tire Width
:The three‐digit
number indicates the tire section
width in millimeters from
sidewall to sidewall.
(C) Aspect Ratio
:A two‐digit
number that indicates the tire
height‐to‐width measurements.
For example, if the tire size
aspect ratio is 75, as shown
in item C of the light truck (LT‐Metric) tire illustration, it
would mean that the tire's
sidewall is 75 percent as high
as it is wide.
(D) Construction Code
:A
letter code is used to indicate
the type of ply construction in
the tire. The letter R means
radial ply construction; the
letter D means diagonal or
bias ply construction; and the
letter B means belted‐bias ply
construction.
(E) Rim Diameter
:Diameter of
the wheel in inches.
(F) Load Range
:Load Range.
(G) Service Description
:The
service description indicates the
load index and speed rating of a
tire. If two numbers are given as
in the example, 120/116, then
this represents the load index for
single versus dual wheel usage (single/dual). The speed rating is
the maximum speed a tire is
certified to carry a load.
Tire Terminology and
Definitions
Air Pressure:The amount
of air inside the tire pressing
outward on each square inch
of the tire. Air pressure is
expressed in kPa (kilopascal)
or psi (pounds per square inch).
Accessory Weight
:The
combined weight of optional
accessories. Some examples
of optional accessories are
automatic transmission, power
steering, power brakes, power
windows, power seats, and air
conditioning.
Aspect Ratio
:The relationship
of a tire's height to its width.

Black plate (64,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-64 Vehicle Care
The malfunction light and the DIC
message should go off at the next
ignition cycle. The sensors are
matched to the tire/wheel positions,
using a TPMS relearn tool, in the
following order: driver side front tire,
passenger side front tire, passenger
side rear tire, and driver side rear.
See your dealer for service or to
purchase a relearn tool.
There are two minutes to match
the first tire/wheel position, and
five minutes overall to match all
four tire/wheel positions. If it takes
longer, the matching process stops
and must be restarted.
The TPMS sensor matching
process is:
1. Set the parking brake.
2. Turn the ignition to ON/RUN withthe engine off.
3. Press the Remote Keyless Entry (RKE) transmitter's LOCK
and UNLOCK buttons at the
same time for approximately
five seconds. The horn sounds twice to signal the receiver
is in relearn mode and TIRE
LEARNING ACTIVE message
displays on the DIC screen.
If the vehicle does not have
RKE, press the Driver
Information Center (DIC) vehicle
information button until the
PRESS
VTO RELEARN TIRE
POSITIONS message displays.
The horn sounds twice to signal
the receiver is in relearn mode
and TIRE LEARNING ACTIVE
message displays on the DIC
screen.
If the vehicle does not have RKE
or DIC buttons, press the trip
odometer reset stem located on
the instrument panel cluster until
the PRESS
VTO RELEARN
TIRE POSITIONS message
displays. The horn sounds twice
to signal the receiver is in
relearn mode and TIRE
LEARNING ACTIVE message
displays on the DIC screen. 4. Start with the driver side
front tire.
5. Place the relearn tool against the tire sidewall, near the valve
stem. Then press the button to
activate the TPMS sensor.
A horn chirp confirms that the
sensor identification code has
been matched to this tire and
wheel position.
6. Proceed to the passenger side front tire, and repeat the
procedure in Step 5.
7. Proceed to the passenger side rear tire, and repeat the
procedure in Step 5.
8. Proceed to the driver side rear tire, and repeat the procedure in
Step 5. The horn sounds two
times to indicate the sensor
identification code has been
matched to the driver side rear
tire, and the TPMS sensor
matching process is no longer
active. The TIRE LEARNING
ACTIVE message on the DIC
display screen goes off.

Black plate (68,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-68 Vehicle Care
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 treadwear indicators. SeeTireInspection on page 10‑65
andTire
Rotation on page 10‑65 for
additional information.
The rubber in tires ages over time.
This also applies to the spare tire,
if the vehicle has one, even if it is
never used. Multiple conditions
including temperatures, loading
conditions, and inflation pressure
maintenance affect how fast aging
takes place. Tires will typically need
to be replaced due to wear before
they may need to be replaced
due to age. Consult the tire
manufacturer for more information
on when tires should be replaced.
Vehicle Storage
Tires age when stored normally
mounted on a parked vehicle. Park
a vehicle that will be stored for at
least a month in a cool, dry, clean
area away from direct sunlight to
slow aging. This area should be
free of grease, gasoline or other
substances that can deteriorate
rubber. Parking for an extended period can
cause flat spots on the tires that
may result in vibrations while
driving. When storing a vehicle for
at least a month, remove the tires
or raise the vehicle to reduce the
weight from the tires.
Buying New Tires
GM has developed and matched
specific tires for the vehicle. The
original equipment tires installed
were designed to meet General
Motors Tire Performance Criteria
Specification (TPC Spec) system
rating. When replacement tires are
needed, GM strongly recommends
buying tires with the same TPC
Spec rating.
GM's exclusive TPC Spec system
considers over a dozen critical
specifications that impact the
overall performance of the
vehicle, including brake system
performance, ride and handling,
traction control, and tire pressure
monitoring performance. GM's TPC

Black plate (98,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-98 Vehicle Care
6. Use an adequate clampingdevice designed for towing to
ensure that the front wheels are
locked into the straight position.
{WARNING
Shifting a four-wheel-drive
vehicle's transfer case into
N (Neutral) can cause the vehicle
to roll even if the transmission is
in P (Park). The driver or others
could be injured. Make sure the
parking brake is firmly set before
the transfer case is shifted to
N (Neutral).
7. Shift the transfer case to N (Neutral). See “Shifting into
Neutral” underFour-Wheel Drive
on page 9‑40 for the proper
procedure to select the neutral
position for the vehicle.
8. Turn the ignition to LOCK/OFF.
After towing, see “Shifting Out of
Neutral” underFour-Wheel Drive on
page 9‑40.
Appearance Care
Exterior Care
Washing the Vehicle
To preserve the vehicle's finish,
wash it often and out of direct
sunlight.
Notice: Do not use petroleum
based, acidic, or abrasive
cleaning agents as they can
damage the vehicle's paint,
metal, or plastic parts. If damage
occurs, it would not be covered
by the vehicle's warranty.
Approved cleaning products
can be obtained from your
dealer. Follow all manufacturer
directions regarding correct
product usage, necessary safety
precautions, and appropriate
disposal of any vehicle care
product.
Notice: Avoid using high
pressure washes closer than
30 cm (12 in) to the surface of the
vehicle. Use of power washers exceeding 8,274 kPa (1,200 psi)
can result in damage or removal
of paint and decals.
Rinse the vehicle well, before
washing and after, to remove all
cleaning agents completely. If they
are allowed to dry on the surface,
they could stain.
Dry the finish with a soft, clean
chamois or an all-cotton towel to
avoid surface scratches and water
spotting.
Finish Care
Application of aftermarket clearcoat
sealant/wax materials is not
recommended. If painted surfaces
are damaged, see your dealer to
have the damage assessed and
repaired. Foreign materials such
as calcium chloride and other salts,
ice melting agents, road oil and tar,
tree sap, bird droppings, chemicals
from industrial chimneys, etc., can
damage the vehicle's finish if they
remain on painted surfaces. Wash
the vehicle as soon as possible.
If necessary, use non-abrasive

Black plate (9,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Service and Maintenance 11-9
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 battery supplies power to
start the engine and operate any
additional electrical accessories.
.To avoid break‐down or failure
to start the vehicle, maintain a
battery with full cranking power.
.Trained dealer technicians have
the diagnostic equipment to test
the battery and ensure that the
connections and cables are
corrosion‐free.
Belts
.Belts may need replacing if
they squeak or show signs of
cracking or splitting.
.Trained dealer technicians
can inspect the belts and
recommend replacement when
necessary. Brakes
Brakes stop the vehicle and are
crucial to safe driving.
.Signs of brake wear may include
chirping, grinding, or squealing
noises, or difficulty stopping.
.Trained dealer technicians have
access to tools and equipment
to inspect the brakes and
recommend quality parts
engineered for the vehicle.
Fluids
Proper fluid levels and approved
fluids protect the vehicle’s
systems and components. See
Recommended Fluids and
Lubricants on page 11‑12 for GM
approved fluids.
.Engine oil and windshield
washer fluid levels should be
checked at every fuel fill.
.Instrument cluster lights may
come on to indicate that fluids
may be low and need to be
filled.

Black plate (10,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
11-10 Service and Maintenance
Hoses
Hoses transport fluids and should
be regularly inspected to ensure
that there are no cracks or leaks.
With a multi‐point inspection, your
dealer can inspect the hoses and
advise if replacement is needed.
Lamps
Properly working headlamps,
taillamps, and brake lamps are
important to see and be seen on
the road.
.Signs that the headlamps need
attention include dimming, failure
to light, cracking, or damage.
The brake lamps need to be
checked periodically to ensure
that they light when braking.
.With a multi‐point inspection,
your dealer can check the lamps
and note any concerns.Shocks and Struts
Shocks and struts help aid in control
for a smoother ride.
.Signs of wear may include
steering wheel vibration,
bounce/sway while braking,
longer stopping distance,
or uneven tire wear.
.As part of the multi‐point
inspection, trained dealer
technicians can visually inspect
the shocks and struts for
signs of leaking, blown seals,
or damage, and can advise
when service is needed.
Tires
Tires need to be properly inflated,
rotated, and balanced. Maintaining
the tires can save money, fuel, and
can reduce the risk of tire failure.
.Signs that the tires need to be
replaced include three or more
visible treadwear indicators; cord
or fabric showing through the rubber; cracks or cuts in the
tread or sidewall; or a bulge or
split in the tire.
.Trained dealer technicians can
inspect and recommend the
right tires. Your dealer can also
provide tire/wheel balancing
services to ensure smooth
vehicle operation at all speeds.
Your dealer sells and services
name brand tires.
Vehicle Care
To help keep the vehicle looking
like new, vehicle care products are
available from your dealer. For
information on how to clean and
protect the vehicle’s interior and
exterior, see Interior Care on
page 10‑101 andExterior Care on
page 10‑98.