2012 GMC SIERRA 1500 service

Black plate (102,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
9-102 Driving and Operating
TRAILER GAIN: This setting is
displayed any time the Trailer Brake
Display Page is active. This setting
can be adjusted from 0.0 to 10.0
with either a trailer connected or
disconnected. To adjust the Trailer
Gain, press one of the Trailer Gain
adjustment buttons located on the
Trailer Brake Control Panel. Press
and hold a gain button to cause the
Trailer Gain to continuously adjust.
To turn the output to the trailer
off, adjust the Trailer Gain setting
to 0.0 (zero).
0.0 (zero) gain is the factory default
setting. To properly adjust trailer
gain, see“Trailer Gain Adjustment
Procedure” later in this section.
TRAILER OUTPUT: This is
displayed any time a trailer with
electric brakes is connected. Output
to the electric brakes is based on
the amount of vehicle braking
present and relative to the Trailer
Gain setting. Output is displayed
from 0 to 10 bars for each gain
setting. Non-hybrid vehicles with Trailer
Sway Control (TSC) or Hill Start
Assist (HSA), output to the electric
trailer brakes may be displayed
when the systems are active. See
Trailer Sway Control (TSC) on
page 9‑105
andHill Start Assist
(HSA) on page 9‑54.
The Trailer Output will indicate
“- - - - - -” on the Trailer Brake
Display Page whenever the
following occur:
.No trailer is connected
.A trailer without electric brakes
is connected (no DIC message
is displayed)
.A trailer with electric brakes
has become disconnected
(a CHECK TRAILER WIRING
message will also be displayed
on the DIC)
.There is a fault present in the
wiring to the electric trailer
brakes (a CHECK TRAILER
WIRING message will also be
displayed on the DIC)
.There is a fault in the ITBC
system (a SERVICE TRAILER
BRAKE SYSTEM message will
also be displayed in the DIC)
Manual Trailer Brake Apply
The Manual Trailer Brake Apply
Lever is located on the Trailer
Brake Control Panel and is used to
apply the trailer ’s electric brakes
independent of the vehicle’s brakes.
This lever is used in the Trailer Gain
Adjustment Procedure to properly
adjust the power output to the trailer
brakes. Sliding the lever to the left
will apply only the trailer brakes.
The power output to the trailer is
indicated in the Trailer Brake
Display Page on the DIC. If the
vehicle’s service brakes are applied
while using the Manual Trailer Brake
Apply Lever, the trailer output power
will be the greater of the two.
The trailer's and the vehicle's brake
lamps will come on when either
vehicle braking or manual trailer
brakes are applied.

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 (105,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Driving and Operating 9-105
vehicle to an authorized GM dealer
to have the ITBC system diagnosed
and repaired.
If either the CHECK TRAILER
WIRING or SERVICE TRAILER
BRAKE SYSTEM message is
displayed while driving the vehicle,
power is no longer available to
the trailer brakes. When traffic
conditions allow, carefully pull the
vehicle over to the side of the road
and turn the ignition off. Check the
wiring connection to the trailer and
turn the ignition back on. If either of
these messages continues, either
the vehicle or trailer needs service.
An authorized GM dealer may
be able to diagnose and repair
problems with the trailer. However,
any diagnosis and repair of the
trailer is not covered under the
vehicle warranty. Please contact
your trailer dealer for assistance
with trailer repairs and trailer
warranty information.Trailer Sway
Control (TSC)
Non-hybrid vehicles with StabiliTrak
have a Trailer Sway Control (TSC)
feature. If the vehicle is towing a
trailer and the system detects
that the trailer is swaying, the
vehicle brakes are applied without
the driver pressing the brake
pedal. If the vehicle is equipped with
the Integrated Trailer Brake Control
(ITBC) system, StabiliTrak may also
apply the trailer brakes. The TCS/
StabiliTrak warning light will flash on
the instrument panel cluster to notify
the driver to reduce speed. If the
trailer continues to sway, StabiliTrak
will reduce engine torque to help
slow the vehicle. SeeStabiliTrak
®
System on page 9‑55 for more
information.
Adding non‐dealer accessories can
affect the vehicle performance. See
Accessories and Modifications on
page 10‑3 for more information.
Conversions and
Add-Ons
Add-On Electrical
Equipment
Notice:Do not add anything
electrical to the vehicle unless
you check with your dealer first.
Some electrical equipment can
damage the vehicle and the
damage would not be covered
by the vehicle's warranty. Some
add-on electrical equipment can
keep other components from
working as they should.
Add-on equipment can drain the
vehicle's 12‐volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle on page 3‑36 andAdding
Equipment to the Airbag-Equipped
Vehicle on page 3‑37.

Black plate (1,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-1
Vehicle Care
General Information
General Information . . . . . . . . . . 10-2
California Proposition65 Warning . . . . . . . . . . . . . . . . . 10-3
California Perchlorate Materials Requirements . . . . 10-3
Accessories and Modifications . . . . . . . . . . . . . . . 10-3
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 10-4
Hood . . . . . . . . . . . . . . . . . . . . . . . . 10-5
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . 10-6
Engine Oil . . . . . . . . . . . . . . . . . . . 10-7
Engine Oil Life System . . . . . 10-10
Automatic Transmission Fluid (4-Speed Transmission) . . . 10-11
Automatic Transmission Fluid (6-Speed
Transmission) . . . . . . . . . . . . . 10-14
Engine Air Cleaner/Filter . . . . 10-17
Cooling System . . . . . . . . . . . . 10-18
Engine Coolant . . . . . . . . . . . . . 10-19
Engine Overheating . . . . . . . . 10-22 Overheated Engine
Protection
Operating Mode . . . . . . . . . . . 10-24
Engine Fan . . . . . . . . . . . . . . . . . 10-24
Power Steering Fluid . . . . . . . 10-25
Washer Fluid . . . . . . . . . . . . . . . 10-26
Brakes . . . . . . . . . . . . . . . . . . . . . 10-27
Brake Fluid . . . . . . . . . . . . . . . . . 10-28
Battery . . . . . . . . . . . . . . . . . . . . . 10-30
Four-Wheel Drive . . . . . . . . . . . 10-30
Front Axle . . . . . . . . . . . . . . . . . . 10-31
Rear Axle . . . . . . . . . . . . . . . . . . 10-32
Noise Control System . . . . . . 10-34
Starter Switch Check . . . . . . . 10-35
Automatic Transmission Shift Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . 10-35
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . 10-35
Park Brake and P (Park) Mechanism Check . . . . . . . . 10-36
Wiper Blade Replacement . . . . . . . . . . . . . . 10-36
Glass Replacement . . . . . . . . 10-37
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . 10-37
Bulb Replacement
Bulb Replacement . . . . . . . . . . 10-39
Halogen Bulbs . . . . . . . . . . . . . . 10-39
Headlamps, Front Turn Signal, Sidemarker, and
Parking Lamps . . . . . . . . . . . . 10-39
Pick-Up Box Identification and Fender Marker
Lamps . . . . . . . . . . . . . . . . . . . . 10-40
Taillamps (Chassis Cab Models) . . . . . . . . . . . . . . . . . . . 10-40
Taillamps, Turn Signal, Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . 10-41
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . 10-42
License Plate Lamp . . . . . . . . 10-42
Replacement Bulbs . . . . . . . . . 10-43
Electrical System
Electrical System Overload . . . . . . . . . . . . . . . . . . 10-43
Fuses and Circuit Breakers . . . . . . . . . . . . . . . . . . 10-44
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . 10-44
Instrument Panel Fuse Block . . . . . . . . . . . . . . . . . . . . . 10-48

Black plate (2,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-2 Vehicle Care
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . 10-50
Tire Sidewall Labeling . . . . . . 10-52
Tire Designations . . . . . . . . . . . 10-54
Tire Terminology andDefinitions . . . . . . . . . . . . . . . . 10-55
Tire Pressure . . . . . . . . . . . . . . . 10-58
Tire Pressure for High-Speed Operation . . . . . . . . . . . . . . . . . 10-60
Tire Pressure Monitor System . . . . . . . . . . . . . . . . . . . 10-60
Tire Pressure Monitor Operation . . . . . . . . . . . . . . . . . 10-62
Tire Inspection . . . . . . . . . . . . . . 10-65
Tire Rotation . . . . . . . . . . . . . . . 10-65
Dual Tire Rotation . . . . . . . . . . 10-67
When It Is Time for New Tires . . . . . . . . . . . . . . . . . . . . . . 10-68
Buying New Tires . . . . . . . . . . . 10-68
Different Size Tires and Wheels . . . . . . . . . . . . . . . . . . . 10-70 Uniform Tire Quality
Grading . . . . . . . . . . . . . . . . . . . 10-70
Wheel Alignment and Tire Balance . . . . . . . . . . . . . . . . . . . 10-72
Wheel Replacement . . . . . . . . 10-72
Tire Chains . . . . . . . . . . . . . . . . . 10-74
If a Tire Goes Flat . . . . . . . . . . 10-75
Tire Changing . . . . . . . . . . . . . . 10-76
Full-Size Spare Tire . . . . . . . . 10-87
Jump Starting
Jump Starting . . . . . . . . . . . . . . 10-88
Towing
Towing the Vehicle . . . . . . . . . 10-93
Recreational Vehicle
Towing . . . . . . . . . . . . . . . . . . . . 10-93
Appearance Care
Exterior Care . . . . . . . . . . . . . . . 10-98
Interior Care . . . . . . . . . . . . . . . 10-101
Floor Mats . . . . . . . . . . . . . . . . 10-104
General Information
For service and parts needs,
visit your dealer. You will receive
genuine GM parts and GM-trained
and supported service people.
Genuine GM parts have one of
these marks:

Black plate (4,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-4 Vehicle Care
Damage to vehicle components
resulting from modifications or the
installation or use of non‐GM
certified parts, including control
module or software modifications, is
not covered under the terms of the
vehicle warranty and may affect
remaining warranty coverage for
affected parts.
GM Accessories are designed to
complement and function with other
systems on the vehicle. See your
dealer to accessorize the vehicle
using genuine GM Accessories
installed by a dealer technician.
Also, seeAdding Equipment to the
Airbag-Equipped Vehicle on
page 3‑37.Vehicle Checks
Doing Your Own
Service Work
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
{WARNING
It can be dangerous to work on
your vehicle if you do not have
the proper knowledge, service
manual, tools, or parts. Always
follow owner manual procedures
and consult the service manual
for your vehicle before doing any
service work. If doing some of your own service
work, use the proper service
manual. It tells you much more
about how to service the vehicle
than this manual can. To order the
proper service manual, see
Service
Publications Ordering Information
on page 13‑16.
This vehicle has an airbag system.
Before attempting to do your own
service work, see Airbag System
Check on page 3‑38.
Keep a record with all parts receipts
and list the mileage and the date
of any service work performed.
See Maintenance Records on
page 11‑16.

Black plate (8,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
10-8 Vehicle Care
Checking Engine Oil
It is a good idea to check the engine
oil level at each fuel fill. In order to
get an accurate reading, the vehicle
must be on level ground. The
engine oil dipstick handle is a yellow
loop. SeeEngine Compartment
Overview on page 10‑6 for the
location of the engine oil dipstick.
Obtaining an accurate oil level
reading is essential:
1. If the engine has been running recently, turn off the engine and
allow several minutes for the oil
to drain back into the oil pan.
Checking the oil level too soon
after engine shutoff will not
provide an accurate oil level
reading.
2. Pull out the dipstick and clean it with a paper towel or cloth,
then push it back in all the way.
Remove it again, keeping the tip
down, and check the level.
When to Add Engine Oil
If the oil is below the cross-hatched
area at the tip of the dipstick, add
1 L (1 qt) of the recommended oil
and then recheck the level. See
“Selecting the Right Engine Oil” in
this section for an explanation of
what kind of oil to use. For engine
oil crankcase capacity, see
Capacities and Specifications on
page 12‑2.
Notice: Do not add too much oil.
Oil levels above or below the
acceptable operating range
shown on the dipstick are harmful
to the engine. If you find that
you have an oil level above the
operating range, i.e., the engine has so much oil that the oil level
gets above the cross-hatched
area that shows the proper
operating range, the engine could
be damaged. You should drain
out the excess oil or limit driving
of the vehicle and seek a service
professional to remove the
excess amount of oil.
See
Engine Compartment Overview
on page 10‑6 for the location of the
engine oil fill cap.
Add enough oil to put the level
somewhere in the proper operating
range. Push the dipstick all the way
back in when through.
Selecting the Right Engine Oil
Selecting the right engine oil
depends on both the proper oil
specification and viscosity grade.
See Recommended Fluids and
Lubricants on page 11‑12.

Black plate (9,1)GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
Vehicle Care 10-9
Specification
Use and ask for licensed engine
oils with the dexos1™approved
certification mark. Engine oils
meeting the requirements for the
vehicle should have the dexos™1
approved certification mark. This
certification mark indicates that
the oil has been approved to the
dexos1 specification.
Notice: Failure to use the
recommended engine oil or
equivalent can result in engine
damage not covered by the
vehicle warranty. Check with
your dealer or service provider
on whether the oil is approved to
the dexos1 specification. Viscosity Grade
SAE 5W‐30 is the best viscosity
grade for the vehicle. Do not use
other viscosity grade oils such as
SAE 10W‐30, 10W‐40, or 20W‐50.
If in an area of extreme cold, where
the temperature falls below
−20°F
(−29°C), an SAE 0W‐30 oil should
be used. An oil of this viscosity
grade will provide easier cold
starting for the engine at extremely
low temperatures. When selecting
an oil of the appropriate viscosity
grade, always select an oil that
meets the dexos1 specification or
equivalent. See “Specification”for
more information.Engine Oil Additives/Engine
Oil Flushes
Do not add anything to the oil. The
recommended oils with the dexos
specification and displaying the
dexos certification mark are all that
is needed for good performance and
engine protection. Engine oil system flushes are not
recommended and could cause
engine damage not covered by the
vehicle warranty.
What to Do with Used Oil
Used engine oil contains certain
elements that can be unhealthy for
your skin and could even cause
cancer. Do not let used oil stay on
your skin for very long. Clean your
skin and nails with soap and water,
or a good hand cleaner. Wash or
properly dispose of clothing or rags
containing used engine oil. See the
manufacturer's warnings about the
use and disposal of oil products.
Used oil can be a threat to the
environment. If you change your
own oil, be sure to drain all the oil
from the filter before disposal. Never
dispose of oil by putting it in the
trash or pouring it on the ground,
into sewers, or into streams or
bodies of water. Recycle it by taking
it to a place that collects used oil.