2014 GMC SIERRA brake system

Black plate (65,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
Driving and Operating 9-65
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,
six red lights 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 as needed. Cruise control may be
disengaged when the Collision Alert
occurs.
Tailgating Alert
The vehicle ahead indicator will
display amber when you are
following a vehicle ahead much too
closely.

Black plate (76,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
9-76 Driving and Operating
immediately after towing at high
altitude on steep uphill grades, the
vehicle may show signs similar to
engine overheating. To avoid this,
let the engine run while parked,
preferably on level ground, with the
transmission in P (Park) for a few
minutes before turning the engine
off. If the overheat warning comes
on, seeEngine Overheating on
page 10-23.
Parking on Hills
{Warning
Parking the vehicle on a hill with
the trailer attached can be
dangerous. If something goes
wrong, the rig could start to move.
People can be injured, and both
the vehicle and the trailer can be
damaged. When possible, always
park the rig on a flat surface. If parking the rig on a hill:
1. Press the brake pedal, but do
not shift into P (Park) yet. Turn
the wheels into the curb if facing
downhill or into traffic if facing
uphill.
2. Have someone place chocks under the trailer wheels.
3. When the wheel chocks are in place, release the regular brakes
until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking brake and shift
into P (Park).
5. Release the brake pedal.
Leaving After Parking on a Hill
1. Apply and hold the brake pedal.
2. Start the engine.
3. Shift into a gear.
4. Release the parking brake. 5. Let up on the brake pedal.
6. Drive slowly until the trailer is
clear of the chocks.
7. Stop and have someone pick up and store the chocks.
Maintenance when Trailer
Towing
The vehicle needs service more
often when pulling a trailer. See
Maintenance Schedule on
page 11-3. Things that are
especially important in trailer
operation are automatic
transmission fluid, engine oil, axle
lubricant, belts, cooling system, and
brake system. It is a good idea to
inspect these before and during
the trip.
Check periodically to see that all
hitch nuts and bolts are tight.

Black plate (91,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
Driving and Operating 9-91
forward that it will contact the back
of the cab in sharp turns. This is
especially important for short box
pickups. Trailer pin box extensions
and sliding fifth-wheel hitch
assemblies can help this condition.
There should be at least 15 cm (6 in)
of clearance between the top of the
pickup box and the bottom of the
trailer shelf that extends over
the box.
Make sure the hitch is attached to
the tow vehicle frame rails. Do not
use the pickup box for support.
Safety Chains
Always attach chains between the
vehicle and the trailer. Cross the
safety chains under the tongue of
the trailer to help prevent the tongue
from contacting the road if it
becomes separated from the hitch.
Instructions about safety chains
may be provided by the hitch
manufacturer or by the trailer
manufacturer. If the trailer being
towed weighs up to 2 271 kg
(5,000 lb) with a factory-installedstep bumper, safety chains may be
attached to the attaching points on
the bumper; otherwise, safety
chains should be attached to holes
on the trailer hitch platform. Always
leave just enough slack so the
combination can turn. Never allow
safety chains to drag on the ground.
Trailer Brakes
A loaded trailer that weighs more
than 900 kg (2,000 lb) 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.
Do not tap into the vehicle's
hydraulic brake system.
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 equipped, this relay will be 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.
{Caution
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 of 30 amps 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.

Black plate (92,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
9-92 Driving and Operating
Basic Trailer Wiring
All regular, double 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.
Heavy-Duty Trailer Wiring Harness
PackageFor vehicles equipped with
heavy-duty trailering, the harness
connector is mounted in the bumper.
The seven-wire harness contains
the following trailer circuits:
.Green/Violet: Left Stop/Turn
Signal
.Yellow/Gray: Right Stop/Turn
Signal
.Gray/Brown: Taillamps/
Parklamps
.White: Ground
.White/Green: Back-up Lamps
.Red/Green: Battery Feed
.Dark Blue: Trailer Brake
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.
Camper/Fifth-Wheel Trailer Wiring
Package
The seven-wire camper harness is
under the rear bumper, attached to
the frame near the rear
crossmember. A connector must be
added to the wiring harness that
connects to the camper.
The harness contains the following
camper/trailer circuits:
.Green/Violet: Left Stop/Turn
Signal
.Yellow/Gray: Right Stop/Turn
Signal
.Gray/Brown: Taillamps/
Parklamps
.White: Ground
.White/Green: Back-up Lamps
.Red/Green: Battery Feed
.Dark Blue: Trailer Brake

Black plate (94,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
9-94 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
Integrated Trailer Brake Control
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 (95,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
Driving and Operating 9-95
Trailer Brake Control Panel
1. Manual Trailer Brake ApplyLever
2. Trailer Gain Adjustment Buttons
The ITBC system has a control
panel on the instrument panel to the
left of the steering column. See
Instrument Panel on page 1-2. The
control panel allows adjustment to
the amount of output, referred to as
Trailer Gain, available to the trailer
brakes and allows manual
application of the trailer brakes. The
Trailer Brake Control Panel is used along with the Trailer Brake Display
Page on the DIC to adjust and
display power output to the trailer
brakes.
Trailer Brake DIC Display Page
The ITBC system displays
messages in the Driver Information
Center (DIC).
The display page indicates Trailer
Gain setting, power output to the
trailer brakes, trailer connection, and
system operational status.
To display the Trailer Brake Display
Page do any of the following:
.Scroll through the DIC menu
pages.
.Press a Trailer Gain button—If
the Trailer Brake Display Page is
not currently displayed, press a
Trailer Gain button to recall the
current Trailer Gain setting.
Each press and release of the
gain buttons will then change the
Trailer Gain setting.
.Activate the Manual Trailer
Brake Apply Lever.
TRAILER GAIN: 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. Press and hold a gain
button to continuously adjust the
Trailer Gain. To turn the output to
the trailer off, adjust the Trailer Gain
setting to 0.0 (zero).
TRAILER OUTPUT: Displays any
time a trailer with electric brakes is
connected. Output to the trailer
brakes is based on the amount of
vehicle braking present and relative
to the Trailer Gain setting. Output is
displayed from 0 to 100% for each
gain setting.
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
displayed).

Black plate (96,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
9-96 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 any time 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 (97,1)GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
5853626) - 2014 - CRC - 6/6/14
Driving and Operating 9-97
3. Readjust 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 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:
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 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.
2. There is an electrical fault in the wiring to the 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 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