
Black plate (114,1)GMC Sierra Owner Manual - 2011
9-114 Driving and Operating
Trailer Brakes
A loaded trailer that weighs more
than 900 kg (2,000 lbs) needs to
have its own brake system that
is adequate for the weight of the
trailer. Be sure to read and follow
the instructions for the trailer brakes
so they are installed, adjusted, and
maintained properly.
If the vehicle is equipped with
StabiliTrak, the trailer cannot tap
into the vehicle's hydraulic brake
system.
The trailer brake system can tap
into the vehicle's hydraulic brake
system only if:
.The trailer parts can withstand
20 650 kPa (3,000 psi) of
pressure.
.The trailer's brake system
will use less than 0.3 cc
(0.02 cubic inch) of fluid from
the vehicle's master cylinder.
Otherwise, both braking systems
will not work well or at all.If everything checks out this far,
make the brake tap at the port on
the master cylinder that sends the
fluid to the rear brakes. Use only
steel brake tubing to make the tap.
Auxiliary Battery
The auxiliary battery provision can
be used to supply electrical power
to additional equipment that may be
added, such as a slide-in camper.
If the vehicle has this provision,
this relay will be located on the
driver side of the vehicle, next to
the underhood electrical center.
Be sure to follow the proper
installation instructions included
with any electrical equipment that
is installed.
Notice:
Leaving electrical
equipment on for extended
periods will drain the battery.
Always turn off electrical
equipment when not in use
and do not use equipment that
exceeds the maximum amperage
rating for the auxiliary battery
provision.
Trailer Wiring Harness
The vehicle is equipped with one of
the following wiring harnesses for
towing a trailer or hauling a slide-in
camper.
Basic Trailer Wiring
All regular, extended cab and crew
cab pickups have a seven‐wire
trailer towing harness.
For vehicles not equipped with
heavy duty trailering, the harness
is secured to the vehicle's frame
behind the spare tire mount.
The harness requires the installation
of a trailer connector, which is
available through your dealer.
If towing a light‐duty trailer with
a standard four‐way round pin
connector, an adapter is available
from your dealer.

Black plate (115,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-115
Heavy-DutyTrailer Wiring Harness
Package
For vehicles equipped with heavy
duty trailering, the harness is
connected to a bracket on the hitch
platform. The seven-wire harness
contains the following trailer circuits:
.Yellow: Left Stop/Turn Signal
.Dark Green: Right Stop/Turn
Signal
.Brown: Taillamps
.White: Ground
.Light Green: Back-up Lamps
.Red: Battery Feed*
.Dark Blue: Trailer Brake*
*The fuses for these two circuits
are installed in the underhood
electrical center, but the wires are
not connected. They should be
connected by your dealer or a
qualified service center. The fuse
and wire for the ITBC is factory
installed and connected if the
vehicle is equipped with an ITBC.
The fuse for the battery feed is
not required if the vehicle has an
auxiliary battery. If the vehicle does
not have an auxiliary battery, have
your dealer or authorized service
center install the required fuse. If charging a remote (non-vehicle)
battery, press the Tow/Haul Mode
button, if equipped, located at
the end of the shift lever. This will
boost the vehicle system voltage
and properly charge the battery.
If the trailer is too light for Tow/
Haul Mode, or the vehicle is not
equipped with Tow/Haul, turn on
the headlamps as a second way
to boost the vehicle system and
charge the battery.

Black plate (116,1)GMC Sierra Owner Manual - 2011
9-116 Driving and Operating
Camper/Fifth-Wheel Trailer Wiring
Package
The seven-wire camper harness
is located under the front edge of
the pickup box on the driver side
of the vehicle, attached to the
frame bracket. A connector must
be added to the wiring harness
which connects to the camper.
The harness contains the following
camper/trailer circuits:
.Yellow: Left Stop/Turn Signal
.Dark Green: Right Stop/Turn
Signal
.Brown: Taillamps
.White: Ground
.Light Green: Back-up Lamps
.Red: Battery Feed
.Dark Blue: Trailer Brake
If the vehicle is equipped with the
“Heavy-Duty Trailering”option,
please refer to “Heavy-Duty Trailer
Wiring Package” earlier in this
section.
When the camper-wiring harness
is ordered without the heavy-duty
trailering package, an eight-wire
harness with a seven-pin connector
is located at the rear of the vehicle
and is tied to the vehicle's frame.
Electric Brake Control Wiring
Provisions
These wiring provisions are
included with the vehicle as part
of the trailer wiring package. These
provisions are for an electric brake
controller. The instrument panel
contains blunt cut wires behind the
steering column for the trailer brake
controller. The harness contains the
following wires:
.Dark Blue: Brake Signal to
Trailer Connector
.Red/Black: Battery
.Light Blue/White: Brake Switch
.White: Ground
The harness should be installed by
your dealer or a qualified service
center.

Black plate (125,1)GMC Sierra Owner Manual - 2011
Driving and Operating 9-125
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 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 3‑46 andAdding
Equipment to the Airbag-Equipped
Vehicle on page 3‑46.
Adding a Snow Plow or
Similar Equipment
Before installing a snow plow on the
vehicle, here are some things you
need to know:
Notice: If your vehicle does
not have the snow plow prep
package, adding a plow can
damage your vehicle, and the
repairs would not be covered by
warranty. Unless your vehicle was
built to carry a snow plow, do not
add one to your vehicle. If your
vehicle has the snow plow prep
package, called RPO VYU, then
the payload your vehicle can
carry will be reduced when a
snow plow is installed. Your
vehicle can be damaged if either
the front or rear axle ratings or
the Gross Vehicle Weight (GVW)
are exceeded. Some vehicles are built with a
special snow plow prep package,
called RPO VYU. If your vehicle
has this option, you can add a
plow to it, provided certain weights,
such as the weights on the vehicle's
axles and the Gross Vehicle
Weight (GVW), are not exceeded.
The plow the vehicle can carry
depends on many things, such as:
.The options the vehicle came
with, and the weight of those
options.
.The weight and number of
passengers you intend to carry.
.The weight of items added to
the vehicle, like a tool box or
truck cap.
.The total weight of any
additional cargo you intend
to carry.

Black plate (1,1)GMC Sierra Owner Manual - 2011
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 . . . . . 10-11
Automatic Transmission Fluid (4-Speed
Transmission) . . . . . . . . . . . . . 10-13
Automatic Transmission Fluid (6-Speed
Transmission) . . . . . . . . . . . . . 10-16
Engine Air Cleaner/Filter . . . . 10-19
Cooling System . . . . . . . . . . . . 10-20
Engine Coolant . . . . . . . . . . . . . 10-22 Engine Overheating . . . . . . . . 10-25
Overheated Engine
Protection
Operating Mode . . . . . . . . . . . 10-28
Engine Fan . . . . . . . . . . . . . . . . . 10-28
Power Steering Fluid . . . . . . . 10-29
Washer Fluid . . . . . . . . . . . . . . . 10-29
Brakes . . . . . . . . . . . . . . . . . . . . . 10-30
Brake Fluid . . . . . . . . . . . . . . . . . 10-32
Battery . . . . . . . . . . . . . . . . . . . . . 10-34
Four-Wheel Drive . . . . . . . . . . . 10-34
Front Axle . . . . . . . . . . . . . . . . . . 10-36
Rear Axle . . . . . . . . . . . . . . . . . . 10-37
Noise Control System . . . . . . 10-38
Starter Switch Check . . . . . . . 10-39
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . 10-40
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . 10-40
Park Brake and P (Park) Mechanism Check . . . . . . . . 10-40
Wiper Blade Replacement . . . . . . . . . . . . . . 10-41
Glass Replacement . . . . . . . . 10-41
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . 10-42
Bulb Replacement
Bulb Replacement . . . . . . . . . . 10-44
Halogen Bulbs . . . . . . . . . . . . . . 10-44
Headlamps . . . . . . . . . . . . . . . . . 10-44
Pick-Up Box Identification and Fender Marker
Lamps . . . . . . . . . . . . . . . . . . . . 10-45
Taillamps (Chassis Cab Models) . . . . . . . . . . . . . . . . . . . 10-46
Taillamps, Turn Signal, Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . 10-46
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . 10-47
License Plate Lamp . . . . . . . . 10-48
Replacement Bulbs . . . . . . . . . 10-48
Electrical System
Electrical System Overload . . . . . . . . . . . . . . . . . . 10-49
Fuses and Circuit Breakers . . . . . . . . . . . . . . . . . . 10-50
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . 10-50
Instrument Panel Fuse Block . . . . . . . . . . . . . . . . . . . . . 10-54

Black plate (7,1)GMC Sierra Owner Manual - 2011
Vehicle Care 10-7
A.Engine Air Cleaner/Filter on
page 10‑19.
B. Coolant Surge Tank and Pressure Cap. See Cooling
System on page 10‑20.
C. Positive (+) Terminal. See Jump
Starting on page 10‑98.
D. Battery on page 10‑34.
E. Remote Negative (−) Terminal (Out of View). See Jump
Starting on page 10‑98.
F. Automatic Transmission Dipstick (Out of View).
See “Checking the Fluid Level”
under Automatic Transmission
Fluid (4-Speed Transmission)
on page 10‑13 orAutomatic
Transmission Fluid (6-Speed
Transmission) on page 10‑16.
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 10‑20.
J. Power Steering Fluid Reservoir. See Power Steering Fluid on
page 10‑29.
K. Brake Master Cylinder Reservoir. See Brake Fluid on
page 10‑32.
L. Engine Compartment Fuse
Block on page 10‑50.
M. Windshield Washer Fluid Reservoir. See “Adding Washer
Fluid” under Washer Fluid on
page 10‑29.
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 10‑11.
.Always dispose of engine oil
properly. See “What to Do with
Used Oil” in this section.

Black plate (34,1)GMC Sierra Owner Manual - 2011
10-34 Vehicle Care
Battery
If the vehicle is a Hybrid, see
the Hybrid Supplement for more
information.
This vehicle has a maintenance free
battery (or batteries). Refer to the
replacement number on the original
battery label when a new battery is
needed. SeeEngine Compartment
Overview on page 10‑6 for battery
location.
{DANGER
Battery posts, terminals, and
related accessories contain lead
and lead compounds, chemicals
known to the State of California
to cause cancer and reproductive
harm. Wash hands after handling.
Vehicle Storage
{WARNING
Batteries have acid that can burn
you and gas that can explode.
You can be badly hurt if you are
not careful. See Jump Starting on
page 10‑98 for tips on working
around a battery without
getting hurt.
Infrequent Usage: Remove the
black, negative (−) cable from the
battery to keep the battery from
running down.
Extended Storage: Remove the
black, negative (−) cable from the
battery or use a battery trickle
charger.
Four-Wheel Drive
Transfer Case
When to Check Lubricant
Refer to Scheduled Maintenance on
page 11‑2 to determine when to
check the lubricant.
How to Check Lubricant
Electric Shift Transfer Case
A. Fill Plug
B. Drain Plug

Black plate (51,1)GMC Sierra Owner Manual - 2011
Vehicle Care 10-51
FusesUsage
1 Right Trailer
Stop/Turn Lamp
2 Electronic
Suspension
Control, Automatic
Level Control
Exhaust Fuses
Usage
3 Left Trailer
Stop/Turn Lamp
4 Engine Controls
5 Engine Control
Module, Throttle
Control Fuses
Usage
6 Trailer Brake
Controller
7 Front Washer
8 Oxygen Sensor
9 Antilock Brakes
System 2
10 Trailer Back-up
Lamps
11 Driver Side
Low-Beam
Headlamp
12 Engine Control
Module (Battery)
13 Fuel Injectors,
Ignition Coils
(Right Side)
14 Transmission
Control Module
(Battery)
15 Vehicle Back-up
Lamps