2012 GMC SIERRA 1500 ECU

Black plate (13,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Keys, Doors, and Windows 2-13
Immobilizer Operation
This vehicle has PASS-Key®III+
(Personalized Automotive Security
System) theft-deterrent system.
PASS-Key III+ is a passive
theft-deterrent system.
The system is automatically armed
when the key is removed from the
ignition.
The system is automatically
disarmed when the key is turned
to ON/RUN, ACC/ACCESSORY,
or START from the LOCK/OFF
position.
You do not have to manually arm or
disarm the system.
The security light will come on if
there is a problem with arming or
disarming the theft-deterrent
system.
When the PASS-Key III+ system
senses that someone is using the
wrong key, it prevents the vehicle
from starting. Anyone using a
trial-and-error method to start the vehicle will be discouraged because
of the high number of electrical key
codes.
If the engine does not start and the
security light on the instrument
panel cluster comes on when trying
to start the vehicle, there may be a
problem with the theft-deterrent
system. Turn the ignition off and try
again.
If the engine still does not start, and
the key appears to be undamaged,
try another ignition key. At this time,
you may also want to check the
fuse. See
Fuses and Circuit
Breakers on page 10‑44. If the
engine still does not start with the
other key, the vehicle needs service.
If the vehicle does start, the first key
may be faulty. See your dealer who
can service the PASS-Key III+ to
have a new key made.
It is possible for the PASS-Key III+
decoder to learn the transponder
value of a new or replacement key.
Up to 10 keys may be programmed for the vehicle. The following
procedure is for programming
additional keys only. If all the
currently programmed keys are lost
or do not operate, you must see
your dealer or a locksmith who can
service PASS-Key III+ to have keys
made and programmed to the
system.
See your dealer or a locksmith who
can service PASS-Key III+ to get a
new key blank cut exactly as the
ignition key that operates the
system.
To program the new additional key:
1. Verify that the new key has
a
1stamped on it.
2. Insert the original, already programmed key in the ignition
and start the engine. If the
engine will not start, see your
dealer for service.
3. After the engine has started, turn the key to LOCK/OFF, and
remove the key.

Black plate (14,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
2-14 Keys, Doors, and Windows
4. Insert the new key to beprogrammed and turn it to the
ON/RUN position within
five seconds of turning the
ignition to the LOCK/OFF
position in Step 3.
The security light will turn off
once the key has been
programmed.
5. Repeat Steps 1 through 4 if additional keys are to be
programmed.
If you lose or damage your
PASS-Key III+ key, see your dealer
or a locksmith who can service
PASS-Key III+ to have a new
key made.
Do not leave the key or device
that disarms or deactivates the
theft-deterrent system in the vehicle.Exterior Mirrors
Convex Mirrors
{WARNING
A convex mirror can make things,
like other vehicles, look farther
away than they really are. If you
cut too sharply into the right lane,
you could hit a vehicle on the
right. Check the inside mirror or
glance over your shoulder before
changing lanes.
The passenger side mirror is convex
shaped. A convex mirror's surface is
curved so more can be seen from
the driver seat.
Manual Mirrors
If the vehicle has manual mirrors,
they can be adjusted by moving the
mirror up and down or left to right to
see a little of the side of the vehicle,
and have a clear view behind the
vehicle.
Using hood-mounted air deflectors
and add-on convex mirror
attachments could decrease mirror
performance.

Black plate (1,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Seats and Restraints 3-1
Seats and
Restraints
Head Restraints
Head Restraints . . . . . . . . . . . . . . . 3-2
Front Seats
Seat Adjustment . . . . . . . . . . . . . . 3-3
Center Seat . . . . . . . . . . . . . . . . . . . 3-4
Power Seat Adjustment . . . . . . . 3-4
Lumbar Adjustment . . . . . . . . . . . 3-4
Reclining Seatbacks . . . . . . . . . . 3-5
Memory Seats . . . . . . . . . . . . . . . . 3-7
Heated and Ventilated FrontSeats . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Rear Seats
Rear Seats (Extended CabFull Bench) . . . . . . . . . . . . . . . . . 3-10
Rear Seats (All Split Bench and Hybrid Full Bench) . . . . . 3-11
Safety Belts
Safety Belts . . . . . . . . . . . . . . . . . . 3-12
How to Wear Safety BeltsProperly . . . . . . . . . . . . . . . . . . . . 3-13
Lap-Shoulder Belt . . . . . . . . . . . 3-14 Safety Belt Use During
Pregnancy . . . . . . . . . . . . . . . . . . 3-19
Lap Belt (Crew and Extended Cab) . . . . . . . . . . . . . 3-19
Safety Belt Extender . . . . . . . . . 3-20
Safety System Check . . . . . . . . 3-20
Safety Belt Care . . . . . . . . . . . . . 3-20
Replacing Safety Belt System
Parts after a Crash . . . . . . . . . 3-21
Airbag System
Airbag System . . . . . . . . . . . . . . . 3-21
Where Are the Airbags? . . . . . 3-23
When Should an AirbagInflate? . . . . . . . . . . . . . . . . . . . . . 3-25
What Makes an Airbag Inflate? . . . . . . . . . . . . . . . . . . . . . 3-27
How Does an Airbag Restrain? . . . . . . . . . . . . . . . . . . . 3-27
What Will You See after an Airbag Inflates? . . . . . . . . . . . . 3-27
Airbag On-Off Switch . . . . . . . . 3-29
Passenger Sensing System . . . . . . . . . . . . . . . . . . . . . 3-32
Servicing the Airbag-Equipped Vehicle . . . . . . . . . . . . . . . . . . . . . 3-36 Adding Equipment to the
Airbag-Equipped Vehicle . . . 3-37
Airbag System Check . . . . . . . . 3-38
Replacing Airbag System Parts after a Crash . . . . . . . . . 3-38
Child Restraints
Older Children . . . . . . . . . . . . . . . 3-39
Infants and Young
Children . . . . . . . . . . . . . . . . . . . . 3-41
Child Restraint Systems . . . . . 3-44
Where to Put the Restraint . . . 3-45
Lower Anchors and Tethers for Children (LATCH
System) . . . . . . . . . . . . . . . . . . . . 3-47
Replacing LATCH System Parts After a Crash . . . . . . . . . 3-55
Securing Child Restraints (Rear Seat Position) . . . . . . . . 3-55
Securing Child Restraints (Center Front Seat
Position) . . . . . . . . . . . . . . . . . . . 3-58
Securing Child Restraints (Right Front Seat
Position) . . . . . . . . . . . . . . . . . . . 3-58

Black plate (15,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Seats and Restraints 3-15
Engaging the child restraint
locking feature may affect the
passenger sensing system,
if equipped. SeePassenger
Sensing System on page 3‑32
for more information.
If the belt stops before it reaches
the buckle, when using the
lap-shoulder belt in a rear center
seating position of a crew-cab,
tilt the latch plate and keep
pulling the safety belt until it can
be buckled.
3. Push the latch plate into the buckle until it clicks.
Pull up on the latch plate to
make sure it is secure. If the belt
is not long enough, see Safety
Belt Extender on page 3‑20.
If the latch plate will not go fully
into the buckle, check if the
correct buckle is being used.
Position the release button on
the buckle so that the safety belt
could be quickly unbuckled if
necessary. 4. If equipped with a shoulder belt
height adjuster, move it to the
height that is right for you. See
“Shoulder Belt Height Adjuster”
later in this section.
5. To make the lap part tight, pull
up on the shoulder belt.
It may be necessary to pull
stitching on the safety belt
through the latch plate to fully
tighten the lap belt on smaller
occupants.

Black plate (20,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
3-20 Seats and Restraints
To make the belt shorter, pull its free
end as shown until the belt is snug.
If the belt is not long enough, see
Safety Belt Extender on page 3‑20.
Make sure the release button on the
buckle is positioned so you would
be able to unbuckle the safety belt
quickly if necessary.
Safety Belt Extender
If the vehicle's safety belt will fasten
around you, you should use it.
But if a safety belt is not long
enough, your dealer will order you
an extender. When you go in to
order it, take the heaviest coat you
will wear, so the extender will be
long enough for you. To help avoid
personal injury, do not let someone
else use it, and use it only for the
seat it is made to fit. The extender
has been designed for adults. Never
use it for securing child seats. To
wear it, attach it to the regular safety
belt. For more information, see the
instruction sheet that comes with
the extender.
Safety System Check
Now and then, check that the safety
belt reminder light, safety belts,
buckles, latch plates, retractors,
and anchorages are all working
properly. Look for any other loose or
damaged safety belt system parts
that might keep a safety belt systemfrom doing its job. See your dealer
to have it repaired. Torn or frayed
safety belts may not protect you in a
crash. They can rip apart under
impact forces. If a belt is torn or
frayed, get a new one right away.
Make sure the safety belt reminder
light is working. See
Safety Belt
Reminders on page 5‑17.
Keep safety belts clean and dry.
See Safety Belt Care on page 3‑20.
Safety Belt Care
Keep belts clean and dry.
{WARNING
Do not bleach or dye safety belts.
It may severely weaken them. In
a crash, they might not be able
to provide adequate protection.
Clean safety belts only with mild
soap and lukewarm water.

Black plate (23,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Seats and Restraints 3-23
{WARNING
Children who are up against,
or very close to, any airbag
when it inflates can be seriously
injured or killed. Airbags plus
lap-shoulder belts offer protection
for adults and older children, but
not for young children and infants.
Neither the vehicle safety belt
system nor its airbag system
is designed for them. Young
children and infants need the
protection that a child restraint
system can provide. Always
secure children properly in the
vehicle. To read how, seeOlder
Children on page 3‑39 orInfants
and Young Children on
page 3‑41.
There is an airbag readiness light
on the instrument panel cluster,
which shows the airbag symbol.
The system checks the airbag
electrical system for malfunctions.
The light tells you if there is an
electrical problem. See Airbag
Readiness Light on page 5‑18 for
more information.
Where Are the Airbags?
The driver airbag is in the middle of
the steering wheel.

Black plate (25,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Seats and Restraints 3-25
{WARNING
If something is between an
occupant and an airbag, the
airbag might not inflate properly
or it might force the object into
that person causing severe injury
or even death. The path of an
inflating airbag must be kept
clear. Do not put anything
between an occupant and an
airbag, and do not attach or put
anything on the steering wheel
hub or on or near any other
airbag covering.
Do not use seat accessories that
block the inflation path of a
seat-mounted side impact airbag.
Never secure anything to the roof
of a vehicle with roof-rail airbags
by routing a rope or tie‐down
through any door or window
opening. If you do, the path of an
inflating roof-rail airbag will be
blocked.
When Should an Airbag
Inflate?
Frontal airbags are designed to
inflate in moderate to severe frontal
or near-frontal crashes to help
reduce the potential for severe
injuries mainly to the driver's or right
front passenger's head and chest.
However, they are only designed
to inflate if the impact exceeds a
predetermined deployment
threshold. Deployment thresholds
are used to predict how severe a
crash is likely to be in time for the
airbags to inflate and help restrain
the occupants.
Whether the frontal airbags will
or should deploy is not based on
how fast your vehicle is traveling.
It depends largely on what you hit,
the direction of the impact, and how
quickly your vehicle slows down.Frontal airbags may inflate at
different crash speeds. For
example:.If the vehicle hits a stationary
object, the airbags could inflate
at a different crash speed than if
the vehicle hits a moving object.
.If the vehicle hits an object that
deforms, the airbags could
inflate at a different crash speed
than if the vehicle hits an object
that does not deform.
.If the vehicle hits a narrow object
(like a pole), the airbags could
inflate at a different crash speed
than if the vehicle hits a wide
object (like a wall).
.If the vehicle goes into an object
at an angle, the airbags could
inflate at a different crash speed
than if the vehicle goes straight
into the object.
Thresholds can also vary with
specific vehicle design.

Black plate (32,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
3-32 Seats and Restraints
Passenger Sensing
System
If the vehicle has one of the
indicators pictured in the following
illustrations, then the vehicle has a
passenger sensing system for the
right front passenger position,
unless there is an airbag off switch
located in the glove box. If there is
an airbag off switch, the vehicle
does not have a passenger sensing
system. SeeAirbag On-Off Switch
on page 3‑29 for more information.
The passenger airbag status
indicator will be visible on the
overhead console when the vehicle
is started.
In addition, if the vehicle has a
passenger sensing system for the
right front passenger position, the
label on the vehicle's sun visors
refers to “ADVANCED AIRBAGS”.
United States
Canada and Mexico
The words ON and OFF, or the
symbol for on and off, will be visible
during the system check. If you
are using remote start to start the
vehicle from a distance, if equipped,
you may not see the system
check. When the system check is
complete, either the word ON or
OFF, or the symbol for on or off, will
be visible. See Passenger Airbag
Status Indicator on page 5‑21. The passenger sensing system will
turn off the right front passenger
frontal airbag under certain
conditions. The driver airbag,
seat‐mounted side impact airbags
(if equipped), and the roof-rail
airbags (if equipped) are not
affected by the passenger sensing
system.
The passenger sensing system
works with sensors that are part
of the right front passenger seat
and safety belt. The sensors are
designed to detect the presence
of a properly-seated occupant
and determine if the right front
passenger frontal airbag should be
enabled (may inflate) or not.
According to accident statistics,
children are safer when properly
secured in a rear seat in the correct
child restraint for their weight
and size.