Page 19 of 556
Black plate (13,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
In Brief 1-13
.On vehicles with four-way
lumbar, press and hold the front
or rear of the control to increase
or decrease lumbar support. To
raise or lower the height of the
support, press and hold the top
or bottom of the control.
See Lumbar Adjustment on
page 3‑4.Reclining Seatbacks
Manual Reclining Seatbacks
To recline a manual seatback:
1. Lift the lever.
2. Move the seatback to the desired position, and then
release the lever to lock the
seatback in place.
3. Push and pull on the seatback to make sure it is locked. To return the seatback to the upright
position:
1. Lift the lever fully without
applying pressure to the
seatback, and the seatback will
return to the upright position.
2. Push and pull on the seatback to make sure it is locked.
See Reclining Seatbacks on
page 3‑5.
Page 21 of 556

Black plate (15,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
In Brief 1-15
SeeMemory Seats on page 3‑7 and
Vehicle Personalization (With DIC
Buttons) on page 5‑48.
Easy Exit Driver Seat
This feature can move the seat
rearward to allow extra room to exit
the vehicle.
B: Press to recall the easy exit
seat position. The vehicle must be
in P (Park).
See Memory Seats on page 3‑7 and
Vehicle Personalization (With DIC
Buttons) on page 5‑48.
Heated and Ventilated
Seats
Heated and Cooled Seat Buttons
Shown, Heated Seat Buttons Similar
If available, the buttons are on the
front doors. To operate, the ignition
must be in ON/RUN.
H: If available, press to cool
the seat.
I: Press to heat the
seatback only.
J: Press to heat the seat and
seatback.
Press the button once for the
highest setting. With each press of
the button, the seat will change to
the next lower setting, and then to
the off setting. The lights indicate
three for the highest setting and one
for the lowest.
See Heated and Ventilated Front
Seats on page 3‑9.
Head Restraint
Adjustment
Do not drive until the head restraints
for all occupants are installed and
adjusted properly.
To achieve a comfortable seating
position, change the seatback
recline angle as little as necessary
while keeping the seat and the
head restraint height in the proper
position.
See Head Restraints on page 3‑2
and Seat Adjustment on page 3‑3.
Page 71 of 556
Black plate (3,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Seats and Restraints 3-3
Rear Seats
The rear seat has adjustable
headrests in the outboard seating
positions.
The height of the headrest can be
adjusted. Pull the headrest up to
raise it. To lower the headrest, push
down on the headrest.
Rear outboard headrests are not
designed to be removed.
Front Seats
Seat Adjustment
{WARNING
You can lose control of the
vehicle if you try to adjust a driver
seat while the vehicle is moving.
The sudden movement could
startle and confuse you, or make
you push a pedal when you do
not want to. Adjust the driver seat
only when the vehicle is not
moving.
To adjust the seat:
1. Lift the bar under the front edgeof the seat cushion to unlock
the seat.
2. Slide the seat to the desired position and release the bar.
3. Try to move the seat back and forth to be sure the seat is
locked in place.
Page 84 of 556

Black plate (16,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
3-16 Seats and Restraints
To unlatch the belt, push the button
on the buckle. The belt should
return to its stowed position.
Before a door is closed, be sure the
safety belt is out of the way. If a
door is slammed against a safety
belt, damage can occur to both the
safety belt and the vehicle.
Shoulder Belt Height Adjuster
The vehicle has a shoulder belt
height adjuster for the driver and
right front passenger.Adjust the height so the shoulder
portion of the belt is on the shoulder
and not falling off of it. The belt
should be close to, but not
contacting, the neck. Improper
shoulder belt height adjustment
could reduce the effectiveness of
the safety belt in a crash. See
How
to Wear Safety Belts Properly on
page 3‑13.Regular and Crew Cab
To move the adjuster down for
the regular and crew cabs,
squeeze the buttons (A) on the sides of the height adjuster and
move the height adjuster to the
desired position.
Extended Cab
On the extended cab, push down
on the release button (A) and move
the height adjuster to the desired
position.
You can move the adjuster up just
by pushing up on the shoulder belt
guide.
Page 413 of 556

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.
Page 424 of 556

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.