change time GMC SIERRA 1500 2012 Service Manual

Black plate (103,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-103
Trailer Gain Adjustment Procedure
Trailer Gain should be set for a
specific trailering condition and
must be adjusted any time vehicle
loading, trailer loading, or road
surface conditions change.
Setting the Trailer Gain properly is
needed for the best trailer stopping
performance. A trailer that is
over-gained may result in locked
trailer brakes. A trailer that is
under-gained may result in not
enough trailer braking. Both of these
conditions may result in poorer
stopping and stability of the vehicle
and trailer.
Use the following procedure to
correctly adjust Trailer Gain for each
towing condition:
1. Make sure the trailer brakes arein proper working condition.
2. Connect a properly loaded trailer to the vehicle and make all
necessary mechanical and electrical connections. See
Vehicle Load Limits on
page 9‑16
for more information.
3. After the electrical connection is made to a trailer equipped with
electric brakes:
.A TRAILER CONNECTED
message will be briefly
displayed on the DIC.
.The Trailer Brake Display
Page will appear on the
DIC showing TRAILER
GAIN and TRAILER
OUTPUT.
.In the Trailer Output display
on the DIC, “- - - - - -”will
disappear if there is no
error present. Connecting
a trailer without electric
brakes will not clear the
six dashed lines.
4. Adjust the Trailer Gain by using the gain adjustment (+ / -)
buttons on the Trailer Brake
Control Panel. 5. Drive the vehicle with the trailer
attached on a level road surface
representative of the towing
condition and free of traffic at
about 32 to 40 km/h (20 to
25 mph) and fully apply the
Manual Trailer Brake Apply
Lever.
Adjusting trailer gain at speeds
lower than 32 to 40 km/h
(20 to 25 mph) may result in
an incorrect gain setting.
6. Adjust the Trailer Gain to just below the point of trailer wheel
lock-up, indicated by trailer
wheel squeal or tire smoke when
a trailer wheel locks.
Trailer wheel lock-up may not
occur if towing a heavily loaded
trailer. In this case, adjust the
Trailer Gain to the highest
allowable setting for the towing
condition.

Black plate (104,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-104 Driving and Operating
7. Re-adjust Trailer Gain any timevehicle loading, trailer loading or
road surface conditions change
or if trailer wheel lock-up is
noticed at any time while towing.
Other ITBC-Related DIC Messages
In addition to displaying TRAILER
GAIN and TRAILER OUTPUT
through the DIC, trailer connection
and ITBC system status are
displayed on the DIC.
TRAILER CONNECTED: This
message will be briefly displayed
when a trailer with electric brakes is
first connected to the vehicle. This
message will automatically turn off
in about 10 seconds. The driver can
also acknowledge this message
before it automatically turns off.
CHECK TRAILER WIRING: This
message will be displayed if:
1. The ITBC system first determines connection to a
trailer with electric brakes and
then the trailer harness becomes
disconnected from the vehicle. If the disconnect occurs while
the vehicle is stationary, this
message will automatically turn
off in about 30 seconds. This
message will also turn off if
the driver acknowledges this
message or if the trailer harness
is re-connected.
If the disconnect occurs while
the vehicle is moving, this
message will continue until
the ignition is turned off. This
message will also turn off if
the driver acknowledges this
message or if the trailer harness
is re-connected.
2. There is an electrical fault in the wiring to the electric trailer
brakes. This message will
continue as long as there is
an electrical fault in the trailer
wiring. This message will
also turn off if the driver
acknowledges this message. To determine if the electrical fault
is on the vehicle side or trailer
side of the trailer wiring harness
connection, do the following:
1. Disconnect the trailer wiring
harness from the vehicle.
2. Turn the ignition off.
3. Wait 10 seconds, then turn the ignition back to RUN.
4. If the CHECK TRAILER WIRING message re-appears, the
electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING
message only re-appears when
connecting the trailer wiring
harness to the vehicle, the
electrical fault is on the
trailer side.
SERVICE TRAILER BRAKE
SYSTEM: This message will be
displayed when there is a problem
with the ITBC system. If this
message persists over multiple
ignition cycles, there is a problem
with the ITBC system. Take the

Black plate (7,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-7
A.Engine Air Cleaner/Filter on
page 10‑17.
B. Coolant Surge Tank and Pressure Cap. See Cooling
System on page 10‑18.
C. Positive (+) Terminal. See Jump
Starting on page 10‑88.
D. Battery on page 10‑30.
E. Remote Negative (−) Terminal (Out of View). See Jump
Starting on page 10‑88.
F. Automatic Transmission Dipstick (Out of View). See
“Checking the Fluid Level”
under Automatic Transmission
Fluid (4-Speed Transmission)
on page 10‑11 orAutomatic
Transmission Fluid (6-Speed
Transmission) on page 10‑14.
G. Engine Oil Fill Cap. See “When
to Add Engine Oil” under
Engine Oil on page 10‑7. H. Engine Oil Dipstick (Out of
View). See “Checking Engine
Oil” under Engine Oil on
page 10‑7.
I. Engine Cooling Fan (Out of View). See Cooling System on
page 10‑18.
J. Power Steering Fluid Reservoir. See Power Steering Fluid on
page 10‑25.
K. Brake Master Cylinder Reservoir. See Brake Fluid on
page 10‑28.
L. Engine Compartment Fuse
Block on page 10‑44.
M. Windshield Washer Fluid Reservoir. See “Adding Washer
Fluid” under Washer Fluid on
page 10‑26.
If the vehicle has a diesel engine
and/or an Allison Transmission, see
the Duramax Diesel Supplement.Engine Oil
For diesel engine vehicles, see
“Engine Oil” in the Duramax Diesel
Supplement.
To ensure proper engine
performance and long life, careful
attention must be paid to engine
oil. Following these simple, but
important steps will help protect
your investment:
.Always use engine oil approved
to the proper specification and of
the proper viscosity grade. See
“Selecting the Right Engine Oil”
in this section.
.Check the engine oil level
regularly and maintain the
proper oil level. See “Checking
Engine Oil” and“When to Add
Engine Oil” in this section.
.Change the engine oil at the
appropriate time. See Engine Oil
Life System on page 10‑10.
.Always dispose of engine oil
properly. See “What to Do with
Used Oil” in this section.

Black plate (10,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-10 Vehicle Care
Engine Oil Life System
When to Change Engine Oil
This vehicle has a computer system
that indicates when to change the
engine oil and filter. This is based
on a combination of factors which
include engine revolutions, engine
temperature, and miles driven.
Based on driving conditions, the
mileage at which an oil change is
indicated can vary considerably. For
the oil life system to work properly,
the system must be reset every time
the oil is changed.
On some vehicles, when the system
has calculated that oil life has been
diminished, a CHANGE ENGINE
OIL SOON message comes on
to indicate that an oil change is
necessary. SeeEngine Oil
Messages on page 5‑42. Change
the oil as soon as possible within
the next 1 000 km (600 mi). It is
possible that, if driving under the best conditions, the oil life system
might indicate that an oil change is
not necessary for up to a year.
The engine oil and filter must be
changed at least once a year and,
at this time, the system must be
reset. For vehicles without the
CHANGE ENGINE OIL SOON
message, an oil change is
needed when the OIL LIFE
REMAINING percentage is near
0%. Your dealer has trained service
people who will perform this work
and reset the system. It is also
important to check the oil regularly
over the course of an oil drain
interval and keep it at the proper
level.
If the system is ever reset
accidentally, the oil must be
changed at 5 000 km (3,000 mi)
since the last oil change.
Remember to reset the oil life
system whenever the oil is changed.
How to Reset the Engine Oil
Life System
Reset the system whenever the
engine oil is changed so that the
system can calculate the next
engine oil change. Always reset the
engine oil life to 100% after every oil
change. It will not reset itself. To
reset the system on most vehicles:
1. Display the OIL LIFE
REMAINING on the DIC.
If the vehicle does not have
DIC buttons, the vehicle must
be in P (Park) to access this
display. See Driver Information
Center (DIC) on page 5‑30.
2. Press and hold the SET/RESET button on the DIC, or the trip
odometer reset stem if the
vehicle does not have DIC
buttons, for more than
five seconds. The oil life will
change to 100%.

Black plate (11,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-11
On all vehicles, the Engine Oil Life
System can be reset as follows:
1. Turn the ignition to ON/RUN withthe engine off.
2. Fully press the accelerator pedal slowly three times within
five seconds.
3. Display the OIL LIFE REMAINING on the DIC.
If the display shows 100%, the
system is reset. See Driver
Information Center (DIC) on
page 5‑30.
If the vehicle has a CHANGE
ENGINE OIL SOON message and it
comes back on when the vehicle
is started and/or the OIL LIFE
REMAINING is near 0%, the engine
oil life system has not been reset.
Repeat the procedure.Automatic Transmission
Fluid (4-Speed
Transmission)
When to Check and Change
Automatic Transmission Fluid
A good time to check the automatic
transmission fluid level is when the
engine oil is changed.
Change the fluid and filter at the
intervals listed in Maintenance
Schedule on page 11‑3 and be
sure to use the transmission fluid
listed in Recommended Fluids and
Lubricants on page 11‑12.
How to Check Automatic
Transmission Fluid
Because this operation can be a
little difficult, it may be best to have
this done at the dealer service
department.
If not taken to the dealer, be sure to
follow all the instructions here or a
false reading on the dipstick could
result. Notice:
Too much or too
little fluid can damage the
transmission. Too much can
mean that some of the fluid could
come out and fall on hot engine
parts or exhaust system parts,
starting a fire. Too little fluid
could cause the transmission
to overheat. Be sure to get an
accurate reading if checking the
transmission fluid.
Wait at least 30 minutes before
checking the transmission fluid level
if you have been driving:
.When outside temperatures are
above 32°C (90°F).
.At high speed for quite a while.
.In heavy traffic —especially in
hot weather.
.While pulling a trailer.
To get the right reading, the fluid
should be at normal operating
temperature, which is 82°C to 93°C
(180°F to 200°F).

Black plate (8,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
13-8 Customer Information
Roadside Assistance is not a part of
the New Vehicle Limited Warranty.
GMC and General Motors of
Canada Limited reserve the right to
make any changes or discontinue
the Roadside Assistance program at
any time without notification.
GMC and General Motors of
Canada Limited reserve the right to
limit services or payment to an
owner or driver if they decide the
claims are made too often, or the
same type of claim is made many
times.
Services Provided
.Emergency Fuel Delivery:
Delivery of enough fuel for the
vehicle to get to the nearest
service station.
.Lock‐Out Service:Service to
unlock the vehicle if you are
locked out. A remote unlock
may be available if you have
OnStar
®. For security reasons,
the driver must present
identification before this service
is given.
.Emergency Tow From a Public
Road or Highway: Tow to the
nearest GMC dealer for warranty
service, or if the vehicle was in
a crash and cannot be driven.
Assistance is also given when
the vehicle is stuck in the sand,
mud, or snow.
.Flat Tire Change: Service to
change a flat tire with the spare
tire. The spare tire, if equipped,
must be in good condition and
properly inflated. It is the owner's
responsibility for the repair or
replacement of the tire if it is not
covered by the warranty.
.Battery Jump Start: Service to
jump start a dead battery.
.Trip Routing Service: Detailed
maps of North America when
requested either with the
most direct route or the most
scenic route. Additional travel
information is also available.
Allow three weeks for delivery.
.Trip Interruption Benefits and
Assistance: If your trip is
interrupted due to a warranty
failure, incidental expenses
may be reimbursed during the
5 years/(160 000 km) 100,000 mi
Powertrain warranty period.
Items considered are hotel,
meals, and rental car.
Services Not Included in
Roadside Assistance
.Impound towing caused by
violation of any laws.
.Legal fines.
.Mounting, dismounting,
or changing of snow tires,
chains, or other traction devices.
.Towing or services for vehicles
driven on a non-public road or
highway.

Black plate (10,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
13-10 Customer Information
Services Provided
.Flat Tire Change: If unable to
change a flat tire, Roadside
Assistance will provide towing
service to the nearest authorized
GMC dealership. It is the
owner's responsibility for the
repair or replacement of the tire.
This service is limited to the
transfer of the vehicle to the
repair facility.
.Emergency Fuel Delivery:
Delivery of enough fuel for the
vehicle to get to the nearest
service station.
.Lock-Out Service: Service to
unlock the vehicle if you are
locked out.
.Battery Jump Start: Service to
jump start a dead battery.
.*Emergency Messages:
Transmission of urgent phone
messages.
.*Emergency Calls: Call for
emergency services.
.*Dealership Location
Assistance: Information
regarding addresses and
telephone numbers for GMC
dealers.
.Emergency Towing: Tow to
the nearest dealer for warranty
service if the vehicle cannot be
driven.
If the vehicle is involved in an
accident during the commission
of a crime, administrative
violation, or breach of traffic
regulations, Roadside
Assistance will not provide
service. When the vehicle is
not accessible to be towed, all
maneuvers required to access it
will be at the owner's expense.
If the vehicle is in another city
outside of your residence,
Roadside Assistance is limited
to moving the vehicle to the
nearest dealer. If you would like
the vehicle moved to a different
dealer, you will be asked to
cover the difference in cost at
the time of the move.If the vehicle cannot be received
by the nearest GMC dealer due
to scheduling conflicts, the
vehicle will be taken to a safe
place where it will remain for up
to 48 hours until it can be taken
to the dealer. If the storage costs
exceed the amount authorized,
the owner is responsible to pay
the difference at the time of
service. Contact Roadside
Assistance for more information
on authorized amounts.
.*Trip Interruption: This service
is provided if you are prevented
from further usage of your
vehicle while traveling and it is
not possible for the nearest
GMC dealership to repair the
vehicle the same day, requiring
the vehicle to stay at the
dealership for a night or more.
If this happens, in addition to the
previously listed services and
prior to confirmation by the
dealership, you are entitled to
choose one of the following
alternatives, within the limits of

Black plate (12,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
13-12 Customer Information
.Acts of terrorism, riot or uproar,
armed forces or police actions
which prevent timely delivery of
assistance services.
.Food service, beverages,
telephone calls, or other extra
costs. Accommodation costs
apply only to Mexico per the
terms and conditions of the
Roadside Assistance program.
.Any damage to the vehicle
without intent, derived from the
services provided.
.Cost of towing a trailer when
choosing a GMC dealer that is
nearest to the temporary storage
facility for the disabled vehicle.
.Cost of all maneuvers required
to access the vehicle when it is
not available to be towed.
.Cost of fuel provided.
Routine vehicle repair costs are
not covered by the Roadside
Assistance program. For more
information, see your new vehicle
warranty. Contacting Roadside Assistance
Roadside Assistance services
are of no cost to you and available
24 hours a day, 365 days a year.
Costs are only incurred in situations
that exceed the limits of the
program, some of which are listed
previously in this section.
To contact Roadside Assistance by
phone, use the following numbers:
Mexico
01-800-466-0801
United States
1-866-466-8902
Canada
1-800-268-6800
E-mail
[email protected]
GMC reserves the right to make
any changes or discontinue the
Roadside Assistance program at
any time without notification.
Scheduling Service
Appointments (U.S. and
Canada)
When the vehicle requires warranty
service, contact your dealer and
request an appointment. By
scheduling a service appointment
and advising the service consultant
of your transportation needs, your
dealer can help minimize your
inconvenience.
If the vehicle cannot be scheduled
into the service department
immediately, keep driving it until it
can be scheduled for service,
unless, of course, the problem is
safety related. If it is, please call
your dealership, let them know this,
and ask for instructions.
If your dealer requests you to bring
the vehicle for service, you are
urged to do so as early in the
work day as possible to allow for
same-day repair.

Black plate (14,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
13-14 Customer Information
Requirements vary and may
include minimum age requirements,
insurance coverage, credit card,
etc. You are responsible for fuel
usage charges and may also be
responsible for taxes, levies, usage
fees, excessive mileage, or rental
usage beyond the completion of the
repair.
It may not be possible to provide a
like vehicle as a courtesy rental.
Additional Program
Information
All program options, such as shuttle
service, may not be available at
every dealer. Please contact your
dealer for specific information
about availability. All Courtesy
Transportation arrangements will be
administered by appropriate dealer
personnel.
General Motors reserves the right
to unilaterally modify, change,
or discontinue Courtesy
Transportation at any time and to
resolve all questions of claimeligibility pursuant to the terms and
conditions described herein at its
sole discretion.
Collision Damage Repair
(U.S. and Canada)
If the vehicle is involved in a
collision and it is damaged, have
the damage repaired by a qualified
technician using the proper
equipment and quality replacement
parts. Poorly performed collision
repairs diminish the vehicle resale
value, and safety performance can
be compromised in subsequent
collisions.
Collision Parts
Genuine GM Collision parts are new
parts made with the same materials
and construction methods as the
parts with which the vehicle was
originally built. Genuine GM
Collision parts are the best choice to
ensure that the vehicle's designed
appearance, durability, and safety
are preserved. The use of Genuine
GM parts can help maintain the GM
New Vehicle Limited Warranty.
Recycled original equipment parts
may also be used for repair. These
parts are typically removed from
vehicles that were total losses in
prior crashes. In most cases, the
parts being recycled are from
undamaged sections of the vehicle.
A recycled original equipment GM
part may be an acceptable choice
to maintain the vehicle's originally
designed appearance and safety
performance; however, the history of
these parts is not known. Such parts
are not covered by the GM New
Vehicle Limited Warranty, and any
related failures are not covered by
that warranty.
Aftermarket collision parts are also
available. These are made by
companies other than GM and may
not have been tested for the vehicle.
As a result, these parts may fit
poorly, exhibit premature durability/
corrosion problems, and may not
perform properly in subsequent

Black plate (17,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Customer Information 13-17
Owner Information
Owner publications are written
specifically for owners and intended
to provide basic operational
information about the vehicle.
The Owner Manual includes the
Maintenance Schedule for all
models.
In-Portfolio: Includes a Portfolio,
Owner Manual, and Warranty
Booklet.
RETAIL SELL PRICE:
$35.00 (U.S.) plus handling and
shipping fees.
Without Portfolio: Owner
Manual only.
RETAIL SELL PRICE:
$25.00 (U.S.) plus handling and
shipping fees.
Current and Past Models
Technical Service Bulletins and
Manuals are available for current
and past model GM vehicles.
ORDER TOLL FREE:
1-800-551-4123 Monday–Friday
8:00 AM –6:00 PM Eastern Time
For Credit Card Orders Only
(VISA-MasterCard-Discover), visit
Helm, Inc. at: www.helminc.com.
Or write to:
Helm, Incorporated
Attention: Customer Service
47911 Halyard Drive
Plymouth, MI 48170
Prices are subject to change
without notice and without incurring
obligation. Allow ample time for
delivery.
All listed prices are quoted in U.S.
funds. Make checks payable in U.S.
funds.
Reporting Safety
Defects
Reporting Safety Defects
to the United States
Government
If you believe that your vehicle
has a defect which could cause
a crash or could cause injury or
death, you should immediately
inform the National Highway
Traffic Safety Administration
(NHTSA) in addition to notifying
General Motors.
If NHTSA receives similar
complaints, it may open an
investigation, and if it finds
that a safety defect exists in a
group of vehicles, it may order
a recall and remedy campaign.