GMC SIERRA 1500 2012 Owners Manual

Black plate (25,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-25
loading, trailer towing, and/or high
outside temperatures, the fan speed
increases as the clutch more fully
engages, so an increase in fan
noise may be heard. 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.
This fan noise may also be heard
when starting the engine. It will go
away as the fan clutch partially
disengages.
If the vehicle has electric cooling
fans, the fans may be heard
spinning at low speed during most
everyday driving. The fans may
turn off if no cooling is required.
Under heavy vehicle loading, trailer
towing, high outside temperatures,
or operation of the air conditioning
system, the fans may change to
high speed and an increase in fan
noise may be heard. This is normal
and indicates that the coolingsystem is functioning properly. The
fans will change to low speed when
additional cooling is no longer
required.
Power Steering Fluid
See
Engine Compartment Overview
on page 10‑6 for reservoir location.
When to Check Power Steering
Fluid
It is not necessary to regularly
check power steering fluid unless
there is a leak suspected in the
system or an unusual noise is
heard. A fluid loss in this system
could indicate a problem. Have the
system inspected and repaired.
How to Check Power Steering
Fluid
Notice:Extremely small amounts
of contamination can cause
steering system damage and
cause it to not work properly. Do
not allow contaminants to contact
the fluid side of the reservoir cap/
dipstick or to enter the reservoir.
To check the power steering fluid:
1. Turn the key off and let the engine compartment cool down.
2. Wipe the cap and the top of the reservoir clean.
3. Unscrew the cap and wipe the dipstick with a clean rag.
4. Replace the cap and completely tighten it.
5. Remove the cap again and look at the fluid level on the dipstick.
The level should be at the FULL
COLD mark. If necessary, add only
enough fluid to bring the level up to
the mark.

Black plate (26,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-26 Vehicle Care
What to Use
To determine what kind of fluid to
use, seeRecommended Fluids and
Lubricants on page 11‑12. Always
use the proper fluid.
Notice: Use of the incorrect fluid
may damage the vehicle and the
damages may not be covered by
the vehicle's warranty. Always
use the correct fluid listed in
Recommended Fluids and
Lubricants on page 11‑12.
Washer Fluid
What to Use
When windshield washer fluid needs
to be added, be sure to read the
manufacturer's instructions before
use. Use a fluid that has sufficient
protection against freezing in an
area where the temperature may fall
below freezing.
Adding Washer Fluid
The vehicle has a low washer fluid
message on the DIC that comes
on when the washer fluid is low.
The message is displayed for
15 seconds at the start of each
ignition cycle. When the WASHER
FLUID LOW ADD FLUID message
displays, washer fluid will need to
be added to the windshield washer
fluid reservoir.
Open the cap with the washer
symbol on it. Add washer fluid until
the tank is full. See Engine
Compartment Overview on
page 10‑6 for reservoir location. Notice
.When using concentrated
washer fluid, follow the
manufacturer's instructions
for adding water.
.Do not mix water with
ready-to-use washer fluid.
Water can cause the solution
to freeze and damage the
washer fluid tank and other
parts of the washer system.
.Fill the washer fluid tank only
three-quarters full when it is
very cold. This allows for
fluid expansion if freezing
occurs, which could
damage the tank if it is
completely full.
.Do not use engine coolant
(antifreeze) in the windshield
washer. It can damage the
windshield washer system
and paint.

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 (29,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-29
Checking Brake Fluid
Check brake fluid by looking at the
brake fluid reservoir. SeeEngine
Compartment Overview on
page 10‑6.
The fluid level should be above
MIN. If it is not, have the brake
hydraulic system checked to see if
there is a leak. After work is done on the brake
hydraulic system, make sure the
level is above the MIN but not over
the MAX mark.
What to Add
Use only new DOT 3 brake fluid
from a sealed container. See
Recommended Fluids and
Lubricants on page 11‑12.
Always clean the brake fluid
reservoir cap and the area around
the cap before removing it. This
helps keep dirt from entering the
reservoir.
{WARNING
With the wrong kind of fluid in
the brake hydraulic system, the
brakes might not work well. This
could cause a crash. Always use
the proper brake fluid.Notice
.Using the wrong fluid
can badly damage brake
hydraulic system parts. For
example, just a few drops of
mineral-based oil, such as
engine oil, in the brake
hydraulic system can
damage brake hydraulic
system parts so badly that
they will have to be replaced.
Do not let someone put in
the wrong kind of fluid.
.If brake fluid is spilled on the
vehicle's painted surfaces,
the paint finish can be
damaged. Be careful not
to spill brake fluid on the
vehicle. If you do, wash it off
immediately.

Black plate (30,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-30 Vehicle Care
Battery
If the vehicle is a Hybrid, see the
Hybrid Supplement for more
information.
This vehicle has a maintenance free
battery (or batteries). Refer to the
replacement number on the original
battery label when a new battery is
needed. SeeEngine Compartment
Overview on page 10‑6 for battery
location.
{WARNING
Battery posts, terminals, and
related accessories contain lead
and lead compounds, chemicals
known to the State of California to
cause cancer and reproductive
harm. Wash hands after handling.
Vehicle Storage
{WARNING
Batteries have acid that can burn
you and gas that can explode.
You can be badly hurt if you are
not careful. See Jump Starting on
page 10‑88 for tips on working
around a battery without
getting hurt.
Infrequent Usage: Remove the
black, negative (−) cable from the
battery to keep the battery from
running down.
Extended Storage: Remove the
black, negative (−) cable from the
battery or use a battery trickle
charger.
Four-Wheel Drive
Transfer Case
When to Check Lubricant
Refer to Maintenance Schedule on
page 11‑3 to determine when to
check the lubricant.
How to Check Lubricant
Electric Shift Transfer Case
A. Fill Plug
B. Drain Plug

Black plate (31,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-31
Manual Shift Transfer Case
A. Fill Plug
B. Drain PlugActive Transfer Case
A. Fill Plug
B. Drain Plug
To get an accurate reading, the
vehicle should be on a level
surface.
If the level is below the bottom of
the fill plug hole, located on the
transfer case, some lubricant will
need to be added. Add enough
lubricant to raise the level to the
bottom of the fill plug hole. Use care
not to overtighten the plug. When to Change Lubricant
Refer to
Maintenance Schedule on
page 11‑3 to determine how often to
change the lubricant.
What to Use
Refer to Recommended Fluids and
Lubricants on page 11‑12 to
determine what kind of lubricant
to use.Front Axle
When to Check and Change
Lubricant
It is not necessary to regularly
check front axle fluid unless a leak
is suspected, or an unusual noise is
heard. A fluid loss could indicate a
problem. Have it inspected and
repaired.

Black plate (32,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-32 Vehicle Care
How to Check Lubricant
To get an accurate reading, the
vehicle should be on a level
surface.
1500 Series
A. Fill Plug
B. Drain Plug
All Except 1500 Series
A. Fill Plug
B. Drain Plug
.When the differential is cold, add
enough lubricant to raise the
level from 0 mm (0 in) to 3.2 mm
(1/8 in) below the fill plug hole.
.When the differential is at
operating temperature (warm),
add enough lubricant to raise the
level to the bottom of the fill
plug hole. What to Use
Refer to
Recommended Fluids
and Lubricants on page 11‑12 to
determine what kind of lubricant
to use.
Rear Axle
When to Check Lubricant
It is not necessary to regularly
check rear axle fluid unless a leak is
suspected or an unusual noise is
heard. A fluid loss could indicate a
problem. Have it inspected and
repaired.
All axle assemblies are filled by
volume of fluid during production.
They are not filled to reach a certain
level. When checking the fluid level
on any axle, variations in the
readings can be caused by factory
fill differences between the minimum
and the maximum fluid volume.

Black plate (33,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-33
Also, if a vehicle has just been
driven before checking the fluid
level, it may appear lower than
normal because fluid has traveled
out along the axle tubes and has
not drained back to the sump
area. Therefore, a reading taken
five minutes after the vehicle has
been driven will appear to have a
lower fluid level than a vehicle that
has been stationary for an hour or
two. Remember that the rear axle
assembly must be supported to get
a true reading.How to Check Lubricant
2500HD with 6.0 L
All Other Series and EnginesTo get an accurate reading, the
vehicle should be on a level
surface.
.For all 4.3 L, 4.8 L and 5.3 L
1500 Series applications, the
proper level is 1.0 mm to
19.0 mm (0.04 in to 0.7 in)
below the bottom of the fill hole,
located on the rear axle. Add
only enough fluid to reach the
proper level.
.For all 6.0 L and 6.2 L
1500 Series applications, the
proper level is from 15 mm to
40 mm (0.6 in to 1.6 in) below
the bottom of the fill plug hole,
located on the rear axle. Add
only enough fluid to reach the
proper level.
.For all 6.0 L 2500HD Series
applications, the proper level is
from 0 mm to 13 mm (0 to 0.5 in)
below the bottom of the fill plug
hole, located on the rear axle.
Add only enough fluid to reach
the proper level.

Black plate (34,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-34 Vehicle Care
.For all 6.6 L Duramax Diesel
2500HD Series applications and
all 3500 Series applications, the
proper level is from 17 mm to
21 mm (0.6 in to 0.8 in) below
the bottom of the fill plug hole,
located on the rear axle. Add
only enough fluid to reach the
proper level.
What to Use
Refer toRecommended Fluids
and Lubricants on page 11‑12 to
determine what kind of lubricant
to use.
Noise Control System
The following information relates
to compliance with federal noise
emission standards for vehicles with
a Gross Vehicle Weight Rating
(GVWR) of more than 4 536 kg
(10,000 lbs). The noise control
system warranty is given in your
warranty booklet.
These standards apply only to
vehicles sold in the United States. Federal law prohibits the following
acts or the causing thereof:
1. The removal or rendering
inoperative by any person,
other than for purposes of
maintenance, repair or
replacement, of any device or
element of design incorporated
into any new vehicle for the
purpose of noise control, prior to
its sale or delivery to the ultimate
purchaser or while it is in use; or
2. The use of the vehicle after such device or element of design has
been removed or rendered
inoperative by any person.
Among those acts presumed to
constitute tampering are the acts
listed below.
Insulation:
Removal of the noise shields or any
underhood insulation. Engine:
Removal or rendering engine speed
governor, if the vehicle has one,
inoperative so as to allow engine
speed to exceed manufacturer
specifications.
Fan and Drive:
.Removal of fan clutch, if the
vehicle has one, or rendering
clutch inoperative.
.Removal of the fan shroud, if the
vehicle has one.
Air Intake:
.Removal of the air cleaner
silencer.
.Modification of the air cleaner.
Exhaust:
.Removal of the muffler and/or
resonator.
.Removal of the exhaust pipes
and exhaust pipe clamps.