warning GMC SIERRA 1500 2012 Owners Manual

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 (35,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-35
Starter Switch Check
{WARNING
When you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured.
1. Before starting this check, be sure there is enough room
around the vehicle.
2. Firmly apply both the parking brake and the regular brake.
See Parking Brake on
page 9‑54.
Do not use the accelerator
pedal, and be ready to turn off
the engine immediately if it
starts.
3. Try to start the engine in each gear. The vehicle should start
only in P (Park) or N (Neutral). If the vehicle starts in any other
position, contact your dealer for
service.Automatic Transmission
Shift Lock Control
Function Check
{WARNING
When you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured.
1. Before starting this check, be sure there is enough room
around the vehicle. It should be
parked on a level surface.
2. Firmly apply the parking brake. See Parking Brake on
page 9‑54.
Be ready to apply the regular
brake immediately if the vehicle
begins to move. 3. With the engine off, turn the
ignition on, but do not start the
engine. Without applying the
regular brake, try to move the
shift lever out of P (Park) with
normal effort. If the shift lever
moves out of P (Park), contact
your dealer for service.
Ignition Transmission
Lock Check
While parked, and with the parking
brake set, try to turn the ignition to
LOCK/OFF in each shift lever
position.
.The ignition should turn to
LOCK/OFF only when the shift
lever is in P (Park).
.The ignition key should come
out only in LOCK/OFF.
Contact your dealer if service is
required.

Black plate (36,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-36 Vehicle Care
Park Brake and P (Park)
Mechanism Check
{WARNING
When you are doing this check,
the vehicle could begin to move.
You or others could be injured
and property could be damaged.
Make sure there is room in front
of the vehicle in case it begins to
roll. Be ready to apply the regular
brake at once should the vehicle
begin to move.Park on a fairly steep hill, with the
vehicle facing downhill. Keeping
your foot on the regular brake, set
the parking brake.
.To check the parking brake's
holding ability: With the engine
running and the transmission in
N (Neutral), slowly remove foot
pressure from the regular brake
pedal. Do this until the vehicle is
held by the parking brake only.
.To check the P (Park)
mechanism's holding ability:
With the engine running, shift
to P (Park). Then release the
parking brake followed by the
regular brake.
Contact your dealer if service is
required.
Wiper Blade Replacement
Windshield wiper blades should be
inspected for wear or cracking.
See Maintenance Schedule on
page 11‑3 for more information on
wiper blade inspection.
Replacement blades come in
different types and are removed in
different ways. To remove the wiper
blade:
1. Pull the windshield wiper arm connector away from the
windshield.
2. Squeeze the grooved areas on
each side of the blade, and turn
the blade assembly away from
the arm connector.

Black plate (39,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-39
8. Turn the vertical aiming screwuntil the headlamp beam is
aimed to the horizontal tape
line. Turn it clockwise or
counterclockwise to raise or
lower the angle of the beam.
9. Make sure that the light from theheadlamp is positioned at the
bottom edge of the horizontal
tape line. The lamp on the
left (A) shows the correct
headlamp aim. The lamp on the
right (B) shows the incorrect
headlamp aim.
10. Repeat Steps 7 through 9 for the opposite headlamp.
Bulb Replacement
For the proper type of replacement
bulbs, see Replacement Bulbs on
page 10‑43.
For any bulb‐changing procedure
not listed in this section, contact
your dealer.
Halogen Bulbs
{WARNING
Halogen bulbs have pressurized
gas inside and can burst if you
drop or scratch the bulb. You or
others could be injured. Be sure
to read and follow the instructions
on the bulb package.
Headlamps, Front Turn
Signal, Sidemarker, and
Parking Lamps
A. Side Marker Lamp
B. Low-Beam Headlamp
C. High-Beam Headlamp
D. Park/Turn Signal Lamp
1. Open the hood. See Hood on
page 10‑5
2. When replacing a driver side bulb on a vehicle with duel
batteries, see your dealer.

Black plate (50,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-50 Vehicle Care
Top View
Harness
Connector Usage
BODY 2 Body Harness
Connector 2
BODY 1 Body Harness
Connector 1
BODY 3 Body Harness
Connector 3
HEADLINER 3 Headliner
Harness
Connector 3 Harness
Connector Usage
HEADLINER 2 Headliner
Harness
Connector 2
HEADLINER 1 Headliner
Harness
Connector 1
SEO/
UPFITTER Special
Equipment Option
Upfitter Harness
Connector
Circuit
Breaker Usage
CB1 Passenger Side
Power Window Circuit
Breaker
CB2 Passenger Seat
Circuit Breaker
CB3 Driver Seat Circuit
Breaker
CB4 Rear Sliding Window
Wheels and Tires
Tires
Every new GM vehicle has
high-quality tires made by a
leading tire manufacturer.
See the warranty manual for
information regarding the tire
warranty and where to get
service. For additional
information refer to the tire
manufacturer.
{WARNING
.Poorly maintained and
improperly used tires are
dangerous.
.Overloading the tires can
cause overheating as a result
of too much flexing. There
could be a blowout and a
serious crash. See Vehicle
Load Limits on page 9‑16.
(Continued)

Black plate (51,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-51
WARNING (Continued)
.Underinflated tires pose the
same danger as overloaded
tires. The resulting crash
could cause serious injury.
Check all tires frequently to
maintain the recommended
pressure. Tire pressure
should be checked when the
tires are cold.
.Overinflated tires are more
likely to be cut, punctured,
or broken by a sudden
impact—such as when
hitting a pothole. Keep tires at
the recommended pressure.
.Worn or old tires can cause a
crash. If the tread is badly
worn, replace them.
.Replace any tires that have
been damaged by impacts
with potholes, curbs, etc.
(Continued)
WARNING (Continued)
.Improperly repaired tires can
cause a crash. Only the
dealer or an authorized tire
service center should repair,
replace, dismount, and mount
the tires.
.Do not spin the tires in
excess of 56 km/h (35 mph)
on slippery surfaces such
as snow, mud, ice, etc.
Excessive spinning may
cause the tires to explode.
SeeTire Pressure for
High-Speed Operation on
page 10‑60 for inflation pressure
adjustment for high speed
driving.
20‐Inch Tires
If the vehicle has 20‐inch
P275/55R20 size tires, they are
classified as touring tires and
are designed for on road use. The low‐profile, wide tread
design is not recommended for
“off‐road”
driving or commercial
uses such as snow plowing.
See Off-Road Driving on
page 9‑6 andAdding a Snow
Plow or Similar Equipment on
page 9‑106 for additional
information.
Notice: 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.

Black plate (60,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-60 Vehicle Care
Tire Pressure for
High-Speed Operation
{WARNING
Driving at high speeds, 160 km/h
(100 mph) or higher, puts an
additional strain on tires.
Sustained high-speed driving
causes excessive heat buildup
and can cause sudden tire failure.
You could have a crash and you
or others could be killed. Some
high-speed rated tires require
inflation pressure adjustment for
high-speed operation. When
speed limits and road conditions
are such that a vehicle can be
driven at high speeds, make sure
the tires are rated for high-speed
operation, in excellent condition,
and set to the correct cold tire
inflation pressure for the
vehicle load.Vehicles with P265/70R17 or
P275/55R20 size tires require
inflation pressure adjustment when
driving the vehicle at speeds of
160 km/h (100 mph) or higher.
Set the cold tire inflation pressure
to 20 kPa (3 psi) above the
recommended cold tire pressure
shown on the Tire and Loading
Information label.
Return the tires to the
recommended cold tire inflation
pressure when high-speed driving
has ended. See
Vehicle Load Limits
on page 9‑16 andTire Pressure on
page 10‑58.
Tire Pressure Monitor
System
The Tire Pressure Monitor System
(TPMS) uses radio and sensor
technology to check tire pressure
levels. The TPMS sensors monitor
the air pressure in your tires and
transmit tire pressure readings to a
receiver located in the vehicle. Each tire, including the spare
(if provided), should be checked
monthly when cold and inflated to
the inflation pressure recommended
by the vehicle manufacturer on the
vehicle placard or tire inflation
pressure label. (If your vehicle has
tires of a different size than the size
indicated on the vehicle placard or
tire inflation pressure label, you
should determine the proper tire
inflation pressure for those tires.)
As an added safety feature, your
vehicle has been equipped with a
tire pressure monitoring system
(TPMS) that illuminates a low tire
pressure telltale when one or
more of your tires is significantly
under‐inflated.
Accordingly, when the low tire
pressure telltale illuminates, you
should stop and check your tires
as soon as possible, and inflate
them to the proper pressure.

Black plate (62,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-62 Vehicle Care
Tire Pressure Monitor
Operation
This vehicle may have a Tire
Pressure Monitor System (TPMS).
The TPMS is designed to warn the
driver when a low tire pressure
condition exists. TPMS sensors are
mounted onto each tire and wheel
assembly, excluding the spare tire
and wheel assembly. The TPMS
sensors monitor the air pressure in
the tires and transmit the tire
pressure readings to a receiver
located in the vehicle.
When a low tire pressure condition
is detected, the TPMS illuminates
the low tire pressure warning light
located on the instrument cluster.If the warning light comes on, stop
as soon as possible and inflate the
tires to the recommended pressure
shown on the Tire and Loading
Information label. See
Vehicle Load
Limits on page 9‑16.
A message to check the pressure in
a specific tire displays in the Driver
Information Center (DIC). The low
tire pressure warning light and the
DIC warning message come on at
each ignition cycle until the tires
are inflated to the correct inflation
pressure. If the vehicle has DIC
buttons, tire pressure levels can be
viewed. For additional information
and details about the DIC operation
and displays, see Driver Information
Center (DIC) on page 5‑30 andTire
Messages on page 5‑45.
The low tire pressure warning light
may come on in cool weather when
the vehicle is first started, and then
turn off as the vehicle is driven.
This could be an early indicator that
the air pressure is getting low and
needs to be inflated to the proper
pressure. A Tire and Loading Information
label shows the size of the original
equipment tires and the correct
inflation pressure for the tires when
they are cold. See
Vehicle Load
Limits on page 9‑16, for an example
of the Tire and Loading Information
label and its location. Also see Tire
Pressure on page 10‑58.
The TPMS can warn about a
low tire pressure condition but it
does not replace normal tire
maintenance. See Tire Inspection
on page 10‑65, Tire Rotation on
page 10‑65 andTires on
page 10‑50.
Notice: Tire sealant materials are
not all the same. A non-approved
tire sealant could damage the
TPMS sensors. TPMS sensor
damage caused by using an
incorrect tire sealant is not
covered by the vehicle
warranty. Always use only the
GM-approved tire sealant
available through your dealer or
included in the vehicle.

Black plate (63,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-63
TPMS Malfunction Light and
Message
The TPMS will not function properly
if one or more of the TPMS sensors
are missing or inoperable. When the
system detects a malfunction, the
low tire pressure warning light
flashes for about one minute and
then stays on for the remainder of
the ignition cycle. A DIC warning
message also displays. The
malfunction light and DIC warning
message come on at each ignition
cycle until the problem is corrected.
Some of the conditions that can
cause these to come on are:
.One of the road tires has been
replaced with the spare tire.
The spare tire does not have a
TPMS sensor. The malfunction
light and the DIC message
should go off after the road tire
is replaced and the sensor
matching process is performed
successfully. See "TPMS Sensor
Matching Process" later in this
section.
.The TPMS sensor matching
process was not done or
not completed successfully
after rotating the tires. The
malfunction light and the DIC
message should go off after
successfully completing the
sensor matching process. See
"TPMS Sensor Matching
Process" later in this section.
.One or more TPMS sensors
are missing or damaged. The
malfunction light and the DIC
message should go off when the
TPMS sensors are installed and
the sensor matching process is
performed successfully. See
your dealer for service.
.Replacement tires or wheels do
not match the original equipment
tires or wheels. Tires and wheels
other than those recommended
could prevent the TPMS from
functioning properly. SeeBuying
New Tires on page 10‑68.
.Operating electronic devices or
being near facilities using radio
wave frequencies similar to the
TPMS could cause the TPMS
sensors to malfunction.
If the TPMS is not functioning
properly, it cannot detect or signal a
low tire condition. See your dealer
for service if the TPMS malfunction
light and DIC message come on
and stay on.
TPMS Sensor Matching
Process
Each TPMS sensor has a unique
identification code. The identification
code needs to be matched to a new
tire/wheel position after rotating the
vehicle’s tires or replacing one or
more of the TPMS sensors. Also,
the TPMS sensor matching
process should be performed after
replacing a spare tire with a road
tire containing the TPMS sensor.