
Black plate (59,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Driving and Operating 9-59
assist on again, select On in the
vehicle personalization menu. The
On with Towbar setting allows for
the parking assist to work properly
with a small item attached to the
trailer hitch. Turn off parking assist
when towing a trailer.
To turn the Rear Vision Camera
(RVC) system rear parking assist
symbols or guidance lines on or off:
1. On the infotainment systemHome screen, press the Settings
screen button, or turn the MENU
knob to highlight Settings and
press MENU.
2. Select Rear Camera.
3. Press Rear Park Assist Symbols or Guidance Lines and then
select Off or On.
Disconnecting the Rear Vision
Camera (RVC)
The RVC must be disconnected if
the tailgate needs to be removed. The RVC is disconnected by
removing the connector from the
electrical junction block mounted on
the left side of the cross member of
the vehicle frame. After
disconnecting, the cap mounted
next to the camera connector must
be relocated so that the open
terminals on the junction block are
covered.
Assistance Systems for
Driving
If equipped, when driving the
vehicle, Forward Collision Alert
(FCA) and Lane Departure Warning
(LDW) can help to avoid a crash or
reduce crash damage.
Forward Collision Alert
(FCA) System
If equipped, the FCA system may
help to avoid or reduce the harm
caused by front-end crashes. When
approaching a vehicle ahead too
quickly, FCA provides a red flashing
alert on the windshield and rapidlybeeps or pulses the driver seat.
FCA also lights an amber visual
alert if following another vehicle
much too closely.
FCA detects vehicles within a
distance of approximately 60 m
(197 ft) and operates at speeds
above 40 km/h (25 mph).
{Warning
FCA is a warning system and
does not apply the brakes. When
approaching a slower-moving or
stopped vehicle ahead too rapidly,
or when following a vehicle too
closely, FCA may not provide a
warning with enough time to help
avoid a crash. FCA does not warn
of pedestrians, animals, signs,
guardrails, bridges, construction
barrels, or other objects. Be ready
to take action and apply the
brakes. For more information, see
Defensive Driving on page 9-3.

Black plate (60,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
9-60 Driving and Operating
FCA can be disabled with the FCA
steering wheel control.
Detecting the Vehicle Ahead
FCA warnings will not occur unless
the FCA system detects a vehicle
ahead. When a vehicle is detected
ahead, the vehicle-ahead indicator
will display green. Vehicles may not
be detected on curves, highway exit
ramps, or hills; or due to poor
visibility. FCA will not detect another
vehicle ahead until it is completely
in the driving lane.
{Warning
FCA does not provide a warning
to help avoid a crash, unless it
detects a vehicle. FCA may not
detect a vehicle ahead if the FCA
sensor is blocked by dirt, snow,
or ice, or if the windshield is
damaged. It may also not detect a
vehicle on winding or hilly roads,
or in conditions that can limit
visibility such as fog, rain,
or snow, or if the headlamps or
windshield are not cleaned or in
proper condition. Keep the
windshield, headlamps, and FCA
sensors clean and in good repair.Collision Alert
When your vehicle approaches
another detected vehicle too rapidly,
the red FCA display will flash on the
windshield. Also, eight rapid
high-pitched beeps will sound from
the front, or both sides of the Safety
Alert Seat will pulse five times.
When this Collision Alert occurs, the
brake system may prepare for driver
braking to occur more rapidly which
can cause a brief, mild deceleration.
Continue to apply the brake pedal

Black plate (63,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Driving and Operating 9-63
If LDW is on, the LDW indicator will
appear green if the system detects
a left or right lane marking while the
vehicle is traveling at 56 km/h
(35 mph) or greater. If the vehicle
crosses a detected lane marking
without using the turn signal in the
lane departure direction, this
indicator will change to amber and
flash. In addition, three beeps will
be sounded from the left or right
side, or the Safety Alert Seat will
pulse three times on either the left
or right side of the seat, depending
on the lane departure direction.
When the System Does Not
Seem to Work Properly
If the LDW symbol does not appear
when the system is on and the
vehicle is traveling at least 56 km/h
(35 mph):
.The lane markings on the road
may not be seen.
.The camera sensor may be
blocked by dirt, snow, or ice.
.The windshield may be
damaged.
.The weather may be limiting
visibility.
This is normal operation; the vehicle
does not need service. Clean the
windshield.
Lane markings may not be detected
on curves, highway exit ramps,
or hills; or due to poor visibility.
If the LDW camera system does not
seem to operate properly, cleaning
the outside of the windshield in front
of the camera sensor may correct
the issue.
{Warning
LDW does not provide a warning
to help avoid a crash, unless it
detects the lane markings. LDW
may not detect the lane markings
if the camera sensor is blocked
by dirt, snow, or ice, or if the
windshield is damaged. It may (Continued)
Warning (Continued)
also not detect a lane on winding
or hilly roads, or in conditions that
can limit visibility such as fog,
rain, or snow, or if the headlamps
or windshield are not cleaned or
in proper condition. Keep the
windshield, headlamps, and
camera sensors clean and in
good repair.
LDW warnings may occur due to tar
marks, shadows, cracks in the road,
or other road imperfections. This is
normal system operation; the
vehicle does not need service.

Black plate (67,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Driving and Operating 9-67
Filling the Tank
If the vehicle has a diesel engine,
see the Duramax diesel supplement
for more information.
{Warning
Fuel vapors and fuel fires burn
violently and can cause injury or
death.
.To help avoid injuries to you
and others, read and follow
all the instructions on the fuel
pump island.
.Turn off the engine when
refueling.
.Keep sparks, flames, and
smoking materials away
from fuel.
.Do not leave the fuel pump
unattended.
.Do not reenter the vehicle
while pumping fuel.(Continued)
Warning (Continued)
.Keep children away from the
fuel pump and never let
children pump fuel.
.Fuel can spray out if the fuel
cap is opened too quickly.
This spray can happen if the
tank is nearly full, and is
more likely in hot weather.
Open the fuel cap slowly and
wait for any hiss noise to stop
then unscrew the cap all
the way.
The fuel cap is behind a hinged fuel
door on the driver side of the
vehicle. Vehicles that have a
FlexFuel badge and a yellow fuel
cap can use either unleaded
gasoline or ethanol fuel containing
up to 85% ethanol (E85). See E85
or FlexFuel on page 9-66.
To remove the fuel cap, turn it
slowly counterclockwise.
If the vehicle is a dual fuel tank
chassis cab model, and it runs out
of fuel, refuel the front fuel tank first
to ensure a quick restart.

Black plate (68,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
9-68 Driving and Operating
Be careful not to spill fuel. Do not
top off or overfill the tank and wait a
few seconds after you have finished
pumping before removing the
nozzle. Clean fuel from painted
surfaces as soon as possible. See
Exterior Care on page 10-98.
When replacing the fuel cap, turn it
clockwise until it clicks. It will require
more effort to turn the fuel cap on
the last turn as you tighten it. Make
sure the cap is fully installed. The
diagnostic system can determine if
the fuel cap has been left off or
improperly installed. This would
allow fuel to evaporate into the
atmosphere. SeeMalfunction
Indicator Lamp on page 5-22.
The TIGHTEN GAS CAP message
displays on the Driver Information
Center (DIC) if the fuel cap is not
properly installed. See Fuel System
Messages on page 5-38 for more
information.{Warning
If a fire starts while you are
refueling, do not remove the
nozzle. Shut off the flow of fuel by
shutting off the pump or by
notifying the station attendant.
Leave the area immediately.
{Caution
If a new fuel cap is needed, be
sure to get the right type of cap
from your dealer. The wrong type
of fuel cap might not fit properly,
might cause the malfunction
indicator lamp to light, and could
damage the fuel tank and
emissions system. See
Malfunction Indicator Lamp on
page 5-22.
Filling a Portable Fuel
Container
{Warning
Filling a portable fuel container
while it is in the vehicle can cause
fuel vapors that can ignite either
by static electricity or other
means. You or others could be
badly burned and the vehicle
could be damaged. Always:
.Use approved fuel
containers.
.Remove the container from
the vehicle, trunk, or pickup
bed before filling.
.Place the container on the
ground.
.Place the nozzle inside the fill
opening of the container
before dispensing fuel, and
(Continued)

Black plate (92,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
9-92 Driving and Operating
Operating the vehicle in Tow/Haul
when lightly loaded or with no trailer
at all will not cause damage.
However, there is no benefit to the
selection of Tow/Haul when the
vehicle is unloaded. Such a
selection when unloaded may result
in unpleasant engine and
transmission driving characteristics
and reduced fuel economy. Tow/
Haul is recommended only when
pulling a heavy trailer or a large or
heavy load.
Integrated Trailer Brake
Control System
The vehicle may have an Integrated
Trailer Brake Control (ITBC) system
for use with electric trailer brakes or
most electric over hydraulic trailer
brakes.
This symbol is on the Trailer Brake
Control Panel on vehicles with an
ITBC system. The power output to
the trailer brakes is based on the
amount of brake pressure being
applied by the vehicle’s brake
system, and on the type of trailer
brakes detected. This available
power output to the trailer brakes
can be adjusted to a wide range of
trailering situations.
The ITBC system is integrated with
the vehicle’s brake, antilock brake,
and StabiliTrak systems. In trailering
conditions that cause the vehicle’s
antilock brake or StabiliTrak
systems to activate, power sent to
the trailer's brakes will be
automatically adjusted to minimize
trailer wheel lock-up. This does not
imply that the trailer has StabiliTrak.
If the vehicle’s brake, antilock brake,
or StabiliTrak systems are not
functioning properly, the ITBC
system may not be fully functional
or may not function at all. Make sure all of these systems are fully
operational to ensure full
functionality of the ITBC system.
The ITBC system is powered
through the vehicle's electrical
system. Turning the ignition off will
also turn off the ITBC system. The
ITBC system is fully functional only
when the ignition is in ON/RUN.
{Warning
Connecting a trailer that has an
air brake system may result in
reduced or complete loss of trailer
braking. There may be an
increase in stopping distance or
trailer instability which could
result in personal injury or
damage to the vehicle, trailer,
or other property. Use the ITBC
system only with electric or
electric over hydraulic trailer
brakes.

Black plate (94,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
9-94 Driving and Operating
.A trailer with electric brakes has
become disconnected (a
CHECK TRAILER WIRING
message will also display on
the DIC).
.There is a fault present in the
wiring to the trailer brakes (a
CHECK TRAILER WIRING
message will also display on
the DIC).
.The ITBC system is not working
due to a fault (a SERVICE
TRAILER BRAKE SYSTEM
message will also display in
the DIC).
Manual Trailer Brake Apply
The Manual Trailer Brake Apply
Lever is used to apply the trailer ’s
electric brakes independent of the
vehicle’s brakes. Sliding the lever to
the left will apply only the trailer
brakes. Use this lever to adjust
Trailer Gain to properly adjust the
power output to the trailer brakes. The trailer's and the vehicle's brake
lamps will come on when either
vehicle brakes or manual trailer
brakes are applied.
Trailer Gain Adjustment Procedure
Trailer Gain should be set for a
specific trailering condition and must
be adjusted anytime vehicle loading,
trailer loading, or road surface
conditions change.
{Warning
Trailer brakes that are
over-gained or under-gained may
not stop the vehicle and the trailer
as intended and can result in a
crash. Always follow the
instructions to set the Trailer Gain
for the proper trailer stopping
performance.
Use the following to adjust Trailer
Gain for each towing condition:
1. 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.
2. Adjust the Trailer Gain, using the Trailer Gain Adjustment Buttons,
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 (95,1)GMC Sierra Owner Manual (GMNA Localizing-U.S/Canada/Mexico-
7299746) - 2015 - crc - 11/11/13
Driving and Operating 9-95
3. Readjust Trailer Gain anytimevehicle 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 OUTPUT through the
DIC, trailer connection and ITBC
system status are displayed on
the DIC.
TRAILER CONNECTED: This
message will briefly display when a
trailer with electric brakes is first
connected to the vehicle. This
message will automatically turn off
in about 10 seconds. This message
can be acknowledged before it
automatically turns off. CHECK TRAILER WIRING: This
message will display if:
.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 it is
acknowledged or if the trailer
harness is reconnected.
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 it is
acknowledged or if the trailer
harness is reconnected.
.There is an electrical fault in the
wiring to the trailer brakes. This
message will continue as long
as there is an electrical fault inthe trailer wiring. This message
will also turn off if it is
acknowledged.
To determine if the electrical fault is
on the vehicle side or trailer side of
the trailer wiring harness
connection:
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 reappears, the
electrical fault is on the
vehicle side.
If the CHECK TRAILER WIRING
message only reappears when
connecting the trailer wiring
harness to the vehicle, the
electrical fault is on the
trailer side.
SERVICE TRAILER BRAKE
SYSTEM: This message will display
when there is a problem with the
ITBC system. If this message