2013 GMC SIERRA electrical

Black plate (21,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
Instruments and Controls 5-21
The light should go out once the
engine starts. If it stays on,
or comes on while driving, there
could be a problem with the
charging system. A charging system
message in the Driver Information
Center (DIC) can also appear. See
Battery Voltage and Charging
Messages on page 5‑37for more
information. This light could indicate
that there are problems with a
generator drive belt, or that there is
an electrical problem. Have it
checked right away. If the vehicle
must be driven a short distance with
the light on, turn off accessories,
such as the radio and air
conditioner.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.Malfunction
Indicator Lamp
A computer system called OBD II
(On-Board Diagnostics-Second
Generation) monitors the operation
of the vehicle to ensure emissions
are at acceptable levels, helping to
maintain a clean environment. The
malfunction indicator lamp comes
on when the vehicle is placed in
ON/RUN, as a check to show it is
working. If it does not, have the
vehicle serviced by your dealer. See
Ignition Positions on page 9‑24.
If the malfunction indicator lamp
comes on while the engine is
running, this indicates that the OBD
II system has detected a problem
and diagnosis and service might be
required. Malfunctions often are indicated by
the system before any problem is
apparent. Being aware of the light
can prevent more serious damage
to the vehicle. This system also
assists the service technician in
correctly diagnosing any
malfunction.
Notice:
If the vehicle is
continually driven with this light
on, the emission controls might
not work as well, the vehicle fuel
economy might not be as good,
and the engine might not run as
smoothly. This could lead to
costly repairs that might not be
covered by the vehicle warranty.
Notice: Modifications made to the
engine, transmission, exhaust,
intake, or fuel system of the
vehicle or the replacement of the
original tires with other than
those of the same Tire
Performance Criteria (TPC) can
affect the vehicle's emission
controls and can cause this light
to come on. Modifications to
these systems could lead to

Black plate (22,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
5-22 Instruments and Controls
costly repairs not covered by the
vehicle warranty. This could also
result in a failure to pass a
required Emission Inspection/
Maintenance test. See
Accessories and Modifications on
page 10‑3.
This light comes on during a
malfunction in one of two ways:
Light Flashing:A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required.
To prevent more serious damage to
the vehicle:
.Reduce vehicle speed.
.Avoid hard accelerations.
.Avoid steep uphill grades.
.If towing a trailer, reduce the
amount of cargo being hauled as
soon as it is possible. If the light continues to flash, find a
safe place to stop and park the
vehicle. Turn the vehicle off, wait at
least 10 seconds, and restart the
engine. If the light is still flashing,
follow the previous steps and see
your dealer for service as soon as
possible.
Light On Steady:
An emission
control system malfunction has
been detected on the vehicle.
Diagnosis and service might be
required.
The following may correct an
emission control system
malfunction:
.Check that the fuel cap is fully
installed. See Filling the Tank on
page 9‑68. The diagnostic
system can determine if the fuel
cap has been left off or
improperly installed. A loose or
missing fuel cap allows fuel to
evaporate into the atmosphere.
A few driving trips with the cap
properly installed should turn the
light off.
.Check that good quality fuel is
used. Poor fuel quality causes
the engine not to run as
efficiently as designed and may
cause stalling after start-up,
stalling when the vehicle is
changed into gear, misfiring,
hesitation on acceleration,
or stumbling on acceleration.
These conditions might go away
once the engine is warmed up.
If one or more of these conditions
occurs, change the fuel brand used.
It may require at least one full tank
of the proper fuel to turn the light off.
See Recommended Fuel on
page 9‑66.
If none of the above have made the
light turn off, your dealer can check
the vehicle. The dealer has the
proper test equipment and
diagnostic tools to fix any
mechanical or electrical problems
that might have developed.

Black plate (38,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
5-38 Instruments and Controls
could drain the battery. Turn off all
unnecessary accessories. Have the
electrical system checked as soon
as possible. See your dealer.
Brake System Messages
SERVICE BRAKE SYSTEM
This message displays along with
the brake system warning light if
there is a problem with the brake
system. SeeBrake System Warning
Light on page 5‑23. If this message
appears, stop as soon as possible
and turn off the vehicle. Restart the
vehicle and check for the message
on the DIC display. If the message
is still displayed or appears again
when you begin driving, the brake
system needs service as soon as
possible. See your dealer.
SERVICE BRAKES SOON
On some vehicles, this message
displays if there is a problem with
the brake system. If this message
appears, stop as soon as possible
and turn off the vehicle. Restart the vehicle and check for the message
on the DIC display. If the message
is still displayed or appears again
when you begin driving, the brake
system needs service. See your
dealer.
SERVICE TRAILER BRAKE
SYSTEM
On vehicles with the Integrated
Trailer Brake Control (ITBC) system,
this message displays and a chime
may sound when there is a problem
with the ITBC system.
When this message displays, power
is no longer available to the trailer
brakes.
As soon as it is safe to do so,
carefully pull your 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 this message still
displays, either your vehicle or the
trailer needs service. See your
dealer.
See
“Integrated Trailer Brake
Control System” underTowing
Equipment on page 9‑89 for more
information.
Door Ajar Messages
DRIVER DOOR OPEN
This message displays and a chime
may sound if the driver door is not
fully closed and the vehicle is
shifted out of P (Park). Stop and turn
off the vehicle, check the door for
obstructions, and close the door
again. Check to see if the message
still appears on the DIC.
HOOD OPEN
This message displays and a chime
may sound if the hood is not fully
closed. Stop and turn off the
vehicle, check the hood for
obstructions, and close the hood
again. Check to see if the message
still appears on the DIC.

Black plate (9,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
Lighting 6-9
Battery Load
Management
The vehicle has Electric Power
Management (EPM) that estimates
the battery's temperature and state
of charge. It then adjusts the voltage
for best performance and extended
life of the battery.
When the battery's state of charge
is low, the voltage is raised slightly
to quickly bring the charge back up.
When the state of charge is high,
the voltage is lowered slightly to
prevent overcharging. If the vehicle
has a voltmeter gauge or a voltage
display on the Driver Information
Center (DIC), you may see the
voltage move up or down. This is
normal. If there is a problem, an
alert will be displayed.
The battery can be discharged at
idle if the electrical loads are very
high. This is true for all vehicles.This is because the generator
(alternator) may not be spinning fast
enough at idle to produce all of the
power needed for very high
electrical loads.
A high electrical load occurs when
several of the following are on, such
as: headlamps, high beams, fog
lamps, rear window defogger,
climate control fan at high speed,
heated seats, engine cooling fans,
trailer loads, and loads plugged into
accessory power outlets.
EPM works to prevent excessive
discharge of the battery. It does this
by balancing the generator's output
and the vehicle's electrical needs.
It can increase engine idle speed to
generate more power whenever
needed. It can temporarily reduce
the power demands of some
accessories.
Normally, these actions occur in
steps or levels, without being
noticeable. In rare cases at the
highest levels of corrective action,
this action may be noticeable to the
driver. If so, a DIC message might
be displayed, such as BATTERY
SAVER ACTIVE, BATTERY
VOLTAGE LOW, or LOW BATTERY.
If one of these messages displays, it
is recommended that the driver
reduce the electrical loads as much
as possible. See
Driver Information
Center (DIC) on page 5‑28.
Battery Power Protection
This feature shuts off the dome and
reading lamps, if they are left on for
more than 10 minutes after the
ignition is turned off. The cargo
lamp shuts off after 20 minutes. This
prevents the battery from
running down.

Black plate (2,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
9-2 Driving and Operating
Fuels in Foreign Countries . . . 9-66
Fuel Additives . . . . . . . . . . . . . . . 9-67
Fuel E85 (85% Ethanol) . . . . . 9-68
Filling the Tank . . . . . . . . . . . . . . 9-68
Filling a Portable FuelContainer . . . . . . . . . . . . . . . . . . . 9-70
Towing
General TowingInformation . . . . . . . . . . . . . . . . . 9-71
Driving Characteristics and Towing Tips . . . . . . . . . . . . . . . . 9-71
Trailer Towing . . . . . . . . . . . . . . . . 9-73
Towing Equipment . . . . . . . . . . . 9-89
Trailer Sway Control (TSC) . . . . . . . . . . . . . 9-100
Conversions and Add-Ons
Add-On ElectricalEquipment . . . . . . . . . . . . . . . . 9-101
Adding a Snow Plow or Similar Equipment . . . . . . . . 9-101
Pickup Conversion to Chassis Cab . . . . . . . . . . . . . . 9-104
Driving Information
Distracted Driving
Distraction comes in many forms
and can take your focus from the
task of driving. Exercise good
judgment and do not let other
activities divert your attention away
from the road. Many local
governments have enacted laws
regarding driver distraction. Become
familiar with the local laws in
your area.
To avoid distracted driving, always
keep your eyes on the road, hands
on the wheel, and mind on the drive.
.Do not use a phone in
demanding driving situations.
Use a hands-free method to
place or receive necessary
phone calls.
.Watch the road. Do not read,
take notes, or look up
information on phones or other
electronic devices.
.Designate a front seat
passenger to handle potential
distractions.
.Become familiar with vehicle
features before driving, such as
programming favorite radio
stations and adjusting climate
control and seat settings.
Program all trip information into
any navigation device prior to
driving.
.Wait until the vehicle is parked
to retrieve items that have fallen
to the floor.
.Stop or park the vehicle to tend
to children.
.Keep pets in an appropriate
carrier or restraint.
.Avoid stressful conversations
while driving, whether with a
passenger or on a cell phone.

Black plate (25,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
Driving and Operating 9-25
{WARNING
Turning off the vehicle while
moving may cause loss of power
assist in the brake and steering
systems and disable the airbags.
While driving, only shut the
vehicle off in an emergency.
If the vehicle cannot be pulled over,
and must be shut off while driving,
turn the ignition to ACC/
ACCESSORY.
Notice: Using a tool to force the
key to turn in the ignition could
cause damage to the switch or
break the key. Use the correct
key, make sure it is all the way in,
and turn it only with your hand.
If the key cannot be turned by
hand, see your dealer.
B (ACC/ACCESSORY): This
position lets things like the radio
and the windshield wipers operate while the engine is off. Use this
position if the vehicle must be
pushed or towed.
C (ON/RUN):
This position can be
used to operate the electrical
accessories and to display some
instrument panel cluster warning
and indicator lights. This position
can also be used for service and
diagnostics, and to verify the proper
operation of the malfunction
indicator lamp as may be required
for emission inspection purposes.
The switch stays in this position
when the engine is running. The
transmission is also unlocked in this
position on automatic transmission
vehicles.
If you leave the key in the ACC/
ACCESSORY or ON/RUN position
with the engine off, the battery could
be drained. You may not be able to
start the vehicle if the battery is
allowed to drain for an extended
period of time. D (START):
This is the position that
starts the engine. When the engine
starts, release the key. The ignition
switch returns to ON/RUN for
driving.
A warning tone will sound when the
driver door is opened and the
ignition is in ACC/ACCESSORY or
LOCK/OFF, and the key is in the
ignition.
Starting the Engine
If the vehicle has a diesel engine,
see the Duramax®diesel
supplement for more information.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Notice: Do not try to shift to
P (Park) if the vehicle is moving.
If you do, you could damage the
transmission. Shift to P (Park)
only when the vehicle is stopped.

Black plate (26,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
9-26 Driving and Operating
Move the shift lever to P (Park) or
N (Neutral). The engine will not start
in any other position. To restart the
engine when the vehicle is already
moving, use N (Neutral) only.
Notice:If you add electrical parts
or accessories, you could change
the way the engine operates. Any
resulting damage would not be
covered by the vehicle warranty.
See Add-On Electrical Equipment
on page 9‑101.
Starting Procedure
1. With your foot off the accelerator pedal, turn the ignition key to
START. When the engine starts,
let go of the key. The idle speed
will go down as your engine gets
warm. Do not race the engine
immediately after starting it.
Operate the engine and
transmission gently to allow the
oil to warm up and lubricate all
moving parts. The vehicle has a
Computer-Controlled Cranking
System. This feature assists in
starting the engine and protects
components. If the ignition key is
turned to the START position,
and then released when the
engine begins cranking, the
engine will continue cranking for
a few seconds or until the
vehicle starts. If the engine does
not start and the key is held in
START for many seconds,
cranking will be stopped after
15 seconds to prevent cranking
motor damage. To prevent gear
damage, this system also
prevents cranking if the engine
is already running. Engine
cranking can be stopped by
turning the ignition switch to the
ACC/ACCESSORY or LOCK/
OFF position.
When the Low Fuel warning
lamp is on and the FUEL LEVEL
LOW message is displayed in
the Driver Information Center
(DIC), the Computer-ControlledCranking System is disabled to
prevent possible vehicle
component damage. When this
happens, hold the ignition switch
in the START position to
continue engine cranking.
Notice: Cranking the engine for
long periods of time, by returning
the key to the START position
immediately after cranking has
ended, can overheat and damage
the cranking motor, and drain the
battery. Wait at least 15 seconds
between each try, to let the
cranking motor cool down.
2. If the engine does not start after 5-10 seconds, especially in very
cold weather (below −18°C or
0°F), it could be flooded with too
much gasoline. Try pushing the
accelerator pedal all the way to
the floor and holding it there as
you hold the key in START for
up to 15 seconds. Wait at least
15 seconds between each try, to
allow the cranking motor to cool
down. When the engine starts,
let go of the key and accelerator.

Black plate (28,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
9-28 Driving and Operating
Engine Coolant Heater
The engine heater can provide
easier starting and better fuel
economy during engine warm-up in
cold weather conditions at or below
−18°C (0°F). Vehicles with an
engine heater should be plugged in
at least four hours before starting.
An internal thermostat in the
plug-end of the cord may exist
which will prevent engine coolant
heater operation at temperatures
above−18°C (0°F).
If the vehicle has a diesel engine,
see the Duramax Diesel supplement
for more information.
To Use the Engine Coolant
Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord. The cord is
secured to the Engine
Compartment Fuse Block with a
clip. Carefully remove the wire tie which bundles the electrical
plug. Do not cut the
electrical cord.
3. Plug the cord into a normal, grounded 110-volt AC outlet.
{WARNING
Plugging the cord into an
ungrounded outlet could cause an
electrical shock. Also, the wrong
kind of extension cord could
overheat and cause a fire. You
could be seriously injured. Plug
the cord into a properly grounded
three-prong 110-volt AC outlet.
If the cord will not reach, use a
heavy-duty three-prong extension
cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug and store the
cord as it was before to keep it
away from moving engine parts.
If you do not, it could be
damaged. The length of time the heater should
remain plugged in depends on
several factors. Ask a dealer in the
area where you will be parking the
vehicle for the best advice on this.
Shifting Into Park
{WARNING
It can be dangerous to get out of
the vehicle if the shift lever is not
fully in P (Park) with the parking
brake firmly set. The vehicle can
roll. If you have left the engine
running, the vehicle can move
suddenly. You or others could be
injured. To be sure the vehicle will
not move, even when you are on
fairly level ground, use the steps
that follow. With four-wheel drive,
if the transfer case is in
N (Neutral), the vehicle will be
free to roll, even if the shift lever
is in P (Park). Be sure the transfer
(Continued)