2012 GMC SIERRA 1500 light

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 (37,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-37
3. Install the new blade onto thearm connector and make sure
the grooved areas are fully set in
the locked position.
For the proper type and size, see
Maintenance Replacement Parts on
page 11‑15.
Glass Replacement
If the windshield or front side
glass must be replaced, see your
dealer to determine the correct
replacement glass.
Headlamp Aiming
The vehicle has a visual optical
headlamp aiming system. The aim
of the headlamps has been preset
at the factory and should need no
further adjustment.
However, if the vehicle is damaged
in a crash, the aim of the headlamps
may be affected and adjustment
may be necessary.
If oncoming vehicles flash their high
beams at you, this may mean the
vertical aim of the headlamps needs
to be adjusted.
It is recommended that the vehicle
be taken to the dealer for service if
the headlamps need to be adjusted.
It is possible, however, to re-aim the
headlamps as described. The vehicle should:.Be placed so the headlamps
are 7.6 m (25 ft) from a
light‐colored wall.
.Have all four tires on a level
surface which is level all the way
to the wall.
.Be placed so it is perpendicular
to the wall.
.Not have any snow, ice, or mud
on it.
.Be fully assembled and all other
work stopped while headlamp
aiming is being performed.
.Be loaded with a full tank of
fuel and one person or 75 kg
(160 lbs) sitting on the
driver seat.
.Have the tires properly inflated.
.Have the spare tire in its proper
location in the vehicle.

Black plate (38,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-38 Vehicle Care
Headlamp aiming is done with the
vehicle's low-beam headlamps.
The high-beam headlamps will be
correctly aimed if the low-beam
headlamps are aimed properly.
To adjust the vertical aim:
1. Open the hood. SeeHood on
page 10‑5
2. Locate the aim dot on the lens of the low‐beam headlamp.
3. Record the distance from the ground to the aim dot on the
low‐beam headlamp.
4. At a wall, measure from the
ground upward (A) to the
recorded distance from
Step 3 and mark it.
5. Draw or tape a horizontal line (B) on the wall the width of the
vehicle at the height of the mark
in Step 4.
Notice: Do not cover a headlamp
to improve beam cut-off when
aiming. Covering a headlamp may
cause excessive heat build-up
which may cause damage to the
headlamp. 6. Turn on the low-beam
headlamps and place a piece
of cardboard or equivalent in
front of the headlamp not being
adjusted. This allows only the
beam of light from the headlamp
being adjusted to be seen on the
flat surface.
7. Locate the vertical headlamp
aiming screws, which are under
the hood near each headlamp
assembly.
The adjustment screw can be
turned with an E8 Torx
®socket.

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 (40,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-40 Vehicle Care
3. When replacing a bulb on thepassenger side, remove the
Engine Air Cleaner cover. See
Engine Air Cleaner/Filter on
page 10‑17 for more information.
4. Reach in and access the bulb sockets from inside the engine
compartment.
5. Turn the bulb socket counterclockwise to remove it
from the headlamp assembly
and pull it straight out.
6. Unplug the electrical connector from the old bulb by releasing
the clips on the bulb socket.
7. Replace it with a new bulb.
8. Plug in the electrical connector.
9. Reinstall the new bulb socket into the headlamp assembly and
turn it clockwise to secure.Pick-Up Box Identification
and Fender Marker
Lamps
The pick-up box identification lamps
are LEDs. For replacement of the
LED lighting assembly contact your
dealer.
To replace a pickup box fender
marker lamp bulb:
1. Press the tab from the back toremove the lamp.
2. Turn the bulb socket counterclockwise to remove
from the lamp assembly.
3. Gently pry the bulb from the socket.
4. Install the new bulb in socket.
5. Reinstall socket into lamp assembly.
6. Reinstall the lamp assembly.
Taillamps (Chassis Cab
Models)
A. Backup Lamp
B. Stoplamp/Taillamp/Turn Signal Lamp
To replace one of these bulbs:
1. Remove the four screws.
2. Lift the lens off the lamp assembly.
3. Turn the old bulb counterclockwise and pull the
it straight out from the socket.

Black plate (48,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-48 Vehicle Care
Instrument Panel Fuse
Block
The instrument panel fuse block
access door is located on the driver
side edge of the instrument panel.
Pull off the cover to access the fuse
block.
The vehicle may not be equipped
with all of the fuses, relays, and
features shown.Fuses Usage
1 Rear Seats
2 Rear Accessory
Power Outlet Fuses Usage
3 Steering Wheel
Controls Backlight
4 Driver Door Module
5 Dome Lamps, Driver
Side Turn Signal

Black plate (49,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-49
FusesUsage
6 Driver Side Turn
Signal, Stoplamp
7 Instrument Panel
Back Lighting
8 Passenger Side Turn
Signal, Stoplamp
9 Passenger Door
Module, Driver Unlock
10 Power Door Lock 2
(Unlock Feature)
11 Power Door Lock 2
(Lock Feature)
12 Stoplamps, Center
High‐Mounted
Stoplamp
13 Rear Climate Controls
14 Power Mirror
15 Body Control
Module (BCM)
16 Accessory Power
Outlets Fuses
Usage
17 Interior Lamps
18 Power Door Lock 1
(Unlock Feature)
19 Rear Seat
Entertainment
20 Ultrasonic Rear
Parking Assist, Power
Liftgate
21 Power Door Lock 1
(Lock Feature)
22 Driver Information
Center (DIC)
23 Rear Wiper
24 Cooled Seats
25 Driver Seat Module,
Remote Keyless Entry
System
26 Driver Power Door
Lock (Unlock Feature) Circuit
Breaker Usage
LT DR Driver Side Power
Window Circuit
Breaker
Harness
Connector Usage
LT DR Driver Door
Harness
Connection
BODY Harness Connector
BODY Harness Connector
Center Instrument Panel Fuse
Block
The center instrument panel fuse
block is located underneath the
instrument panel, to the left of the
steering column.

Black plate (52,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-52 Vehicle Care
Tire Sidewall Labeling
Useful information about a tire
is molded into the sidewall.
The examples show a typical
passenger and light truck tire
sidewall.
Passenger (P‐Metric) Tire
(A) Tire Size:The tire size
code is a combination of letters
and numbers used to define a
particular tire's width, height,
aspect ratio, construction type, and service description. See
the
“Tire Size” illustration later
in this section for more detail.
(B) TPC Spec (Tire
Performance Criteria
Specification)
:Original
equipment tires designed to
GM's specific tire performance
criteria have a TPC specification
code molded onto the sidewall.
GM's TPC specifications meet
or exceed all federal safety
guidelines.
(C) DOT (Department of
Transportation)
:The
Department of Transportation
(DOT) code indicates that
the tire is in compliance
with the U.S. Department of
Transportation Motor Vehicle
Safety Standards. (D) Tire Identification Number
(TIN)
:The letters and numbers
following the DOT code are
the Tire Identification Number
(TIN). The TIN shows the
manufacturer and plant
code, tire size, and date the
tire was manufactured. The TIN
is molded onto both sides of the
tire, although only one side may
have the date of manufacture.
(E) Tire Ply Material
:The type
of cord and number of plies in
the sidewall and under the tread.
(F) Uniform Tire Quality
Grading (UTQG)
:Tire
manufacturers are required
to grade tires based on
three performance factors:
treadwear, traction, and
temperature resistance. For
more information, see Uniform
Tire Quality Grading on
page 10‑70.