2019 GMC SIERRA service

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
Driving and Operating 273
Left Side MirrorDisplayRight Side Mirror Display
When the vehicle is started, both
outside mirror LCA displays will
briefly come on to indicate the
system is operating. When the
vehicle is in a forward gear, the left
or right side mirror display will light
up if a moving vehicle is detected in
the next lane over in that blind zone
or rapidly approaching that zone.
If the turn signal is activated in the
same direction as a detected
vehicle, this display will flash as an
extra warning not to change lanes.
LCA is disabled when the trailer
connection status is displayed.
A DIC message may display. The
SBZA system still operates. LCA can be disabled through
vehicle personalization. When you
disable LCA, SBZA is also disabled.
See
Vehicle Personalization 0170.
If LCA is disabled by the driver, the
LCA mirror displays will not light up.When the System Does Not
Seem to Work Properly
The LCA system requires some
driving for the system to calibrate to
maximum performance. This
calibration may occur more quickly if
the vehicle is driving on a straight
highway road with traffic and
roadside objects (e.g., guardrails,
barriers).
LCA displays may not come on
when passing a vehicle quickly, for
a stopped vehicle, or when towing a
trailer. The LCA detection zones
that extend back from the side of
the vehicle do not move further back
when a trailer is towed. Use caution
while changing lanes when towing a
trailer. LCA may alert to objects
attached to the vehicle, such as a
trailer, bicycle, or object extending
out to either side of the vehicle. Attached objects may also interfere
with the detection of vehicles. This
is normal system operation; the
vehicle does not need service.
LCA may not always alert the driver
to vehicles in the next lane over,
especially in wet conditions or when
driving on sharp curves. The system
does not need to be serviced. The
system may light up due to
guardrails, signs, trees, shrubs, and
other non-moving objects. This is
normal system operation; the
vehicle does not need service.
LCA may not operate when the LCA
sensors in the left or right corners of
the rear bumper are covered with
mud, dirt, snow, ice, or slush, or in
heavy rainstorms. For cleaning
instructions, see "Washing the
Vehicle" under
Exterior Care0408.
If the DIC still displays the system
unavailable message after cleaning
both sides of the vehicle toward the
rear corners of the vehicle, see your
dealer.
If the LCA displays do not light up
when moving vehicles are in the
side blind zone or are rapidly

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
274 Driving and Operating
approaching this zone and the
system is clean, the system may
need service. Take the vehicle to
your dealer.
Radio Frequency Information
SeeRadio Frequency Statement
0 448.
Lane Departure
Warning (LDW)
If equipped, LDW may help avoid
crashes due to unintentional lane
departures. It may provide a
warning if the vehicle is crossing a
detected lane marking without using
a turn signal in the lane departure
direction. Since this system is part
of the Lane Keep Assist (LKA)
system, read the entire LKA section
before using this feature.
Lane Keep Assist (LKA)
If equipped, LKA may help avoid
crashes due to unintentional lane
departures. It may assist by gently
turning the steering wheel if the
vehicle approaches a detected lane marking without using a turn signal
in that direction. It may also provide
a Lane Departure Warning (LDW)
system alert as the lane marking is
crossed. The LKA system will not
assist or provide an LDW alert if it
detects that you are actively
steering. Override LKA by turning
the steering wheel. LKA uses a
camera to detect lane markings
between 60 km/h (37 mph) and
180 km/h (112 mph).
{Warning
The LKA system does not
continuously steer the vehicle.
It may not keep the vehicle in the
lane or give a Lane Departure
Warning (LDW) alert, even if a
lane marking is detected.
The LKA and LDW systems
may not:
. Provide an alert or enough
steering assist to avoid a
lane departure or crash.
(Continued)
Warning (Continued)
.Detect lane markings under
poor weather or visibility
conditions. This can occur if
the windshield or
headlamps are blocked by
dirt, snow, or ice, if they are
not in proper condition, or if
the sun shines directly into
the camera.
. Detect road edges.
. Detect lanes on winding or
hilly roads.
If LKA only detects lane markings
on one side of the road, it will
only assist or provide an LDW
alert when approaching the lane
on the side where it has detected
a lane marking. Even with LKA
and LDW, you must steer the
vehicle. Always keep your
attention on the road and
maintain proper vehicle position
within the lane, or vehicle
damage, injury, or death could (Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
276 Driving and Operating
need service. Clean the outside of
the windshield behind the rearview
mirror.
LKA assistance and/or LDW alerts
may occur due to tar marks,
shadows, cracks in the road,
temporary or construction lane
markings, or other road
imperfections. This is normal system
operation; the vehicle does not need
service. Turn LKA off if these
conditions continue.Fuel
Top Tier Fuel
GM recommends the use of TOP
TIER Detergent Gasoline to keep
the engine clean, reduce engine
deposits, and maintain optimal
vehicle performance. Look for the
TOP TIER Logo or see
www.toptiergas.com for a list of TOP
TIER Detergent Gasoline marketers
and applicable countries.
Recommended Fuel
(Except 6.2L V8 Engine)
For diesel engine vehicles, see
“Fuel for Diesel Engines”in the
Duramax diesel supplement.
If the vehicle has a yellow fuel cap
or a yellow sticker on the fuel door,
E85 or FlexFuel can be used. If the
vehicle does not have a yellow fuel
cap or yellow sticker, do not use
gasoline with ethanol levels greater
than 15% by volume. See E85 or
FlexFuel 0278.
Use regular unleaded gasoline
meeting ASTM specification D4814
with a posted octane rating of 87 or
higher. Do not use gasoline with a
posted octane rating of less than 87,
as this may cause engine knock and
will lower fuel economy.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
Driving and Operating 277
Recommended Fuel (6.2L
V8 Engine)
Do not use any fuel labeled E85 or
FlexFuel. Do not use gasoline with
ethanol levels greater than 15% by
volume.
Premium unleaded gasoline
meeting ASTM specification D4814
with a posted octane rating of 93 is
highly recommended for best
performance and fuel economy.
Unleaded gasoline with an octane
rated as low as 87 can be used.
Using unleaded gasoline rated
below 93 octane, however, will lead
to reduced acceleration and fuel
economy. If knocking occurs, use a
gasoline rated at 93 octane as soon
as possible, otherwise, the engine
could be damaged. If heavy
knocking is heard when using
gasoline with a 93 octane rating, the
engine needs service.
Prohibited Fuels
Caution
Do not use fuels with any of the
following conditions; doing so
may damage the vehicle and void
its warranty:. For vehicles that are not
FlexFuel, fuel labeled
greater than 15% ethanol by
volume, such as mid-level
ethanol blends (16–50%
ethanol), E85, or FlexFuel.
. Fuel with any amount of
methanol, methylal,
ferrocene, and aniline.
These fuels can corrode
metal fuel system parts or
damage plastic and rubber
parts.
. Fuel containing metals such
as methylcyclopentadienyl
manganese tricarbonyl
(Continued)
Caution (Continued)
(MMT), which can damage
the emissions control
system and spark plugs.
. Fuel with a posted octane
rating of less than the
recommended fuel. Using
this fuel will lower fuel
economy and performance,
and may decrease the life of
the emissions catalyst.
Fuels in Foreign
Countries
The U.S., Canada, and Mexico post
fuel octane ratings in anti-knock
index (AKI). For fuel not to use in a
foreign country, see Prohibited
Fuels 0277.
Fuel Additives
TOP TIER Detergent Gasoline is
highly recommended for use with
your vehicle. If your country does
not have TOP TIER Detergent
Gasoline, add ACDelco Fuel

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
286 Driving and Operating
the drive mode that is
appropriate for the road
conditions.
Caution
If the vehicle tires begin to spin
and the vehicle begins to slide
toward the water, remove your
foot from the accelerator pedal
and apply the brake pedal. Seek
help to have the vehicle towed up
the ramp.
Maintenance when Trailer
Towing
The vehicle needs service more
often when used to tow trailers. See
Maintenance Schedule0420. It is
especially important to check the
engine oil, axle lubricant, belts,
cooling system, and brake system
before and during each trip.
Check periodically to see that all
nuts and bolts on the trailer hitch
are tight.
Engine Cooling When Trailer
Towing
The cooling system may temporarily
overheat during severe operating
conditions. See Engine Overheating
0 336.
Trailer Towing
If equipped with a diesel engine,
see the Duramax diesel
supplement.
Caution
Towing a trailer improperly can
damage the vehicle and result in
costly repairs not covered by the
vehicle warranty. To tow a trailer
correctly, follow the directions in
this section and see your dealer
for important information about
towing a trailer with the vehicle.
Trailering is different than just
driving the vehicle by itself.
Trailering means changes in
handling, acceleration, braking,
durability, and fuel economy. Successful, safe trailering takes
correct equipment, and it has to be
used properly.
The following information has many
time-tested, important trailering tips
and safety rules. Many of these are
important for your safety and that of
your passengers. Read this section
carefully before pulling a trailer.
Trailer Weight
{Warning
Never exceed the towing capacity
for your vehicle.
Safe trailering requires monitoring
the weight, speed, altitude, road
grades, outside temperature, and
how frequently the vehicle is used to
tow a trailer.
Trailer Weight Ratings
When towing a trailer, the combined
weight of the vehicle, vehicle
contents, trailer, and trailer contents

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
294 Driving and Operating
1. Left Turn/Brake
2. Taillamps
3. Reverse Lamps
4. Battery Feed
5. Right Turn/Brake
6. Electric Brakes
7. Ground
Use only a round, seven-wire
connector with flat blade terminals
meeting SAE J2863 specifications
for proper electrical connectivity.
Electric Brake Control Wiring
Provisions
If the vehicle is not equipped with
an integrated trailer brake controller,
and the trailer has electric brakes, a
trailer brake controller needs to be
installed on the vehicle. The brake
controller should be installed by
your dealer or a qualified service
center.
If equipped, there is a trailer brake
jumper harness provided with the
vehicle. The connector on the trailer
brake jumper harness is attached to
a mating connector to the left of the
steering wheel behind the knee
bolster. The four blunt cut wires on
the jumper harness need to be
connected to an aftermarket electric
trailer brake controller. The harness
contains the following circuits:Electric Trailer
Brakes Blue
Battery Feed Red/Violet or
Red/Black
Brake Apply
Signal White/Blue Ground Black
The fuse for the electric trailer brake
circuit is in the engine compartment
fuse block, but the wires may not be
connected. They should be
connected by your dealer or a
qualified service center.
Refer to the aftermarket electric
trailer brake controller owner's
manual to determine wire color
coding of the electric trailer brake
controller. The wire colors on the
brake controller may be different
from the vehicle.
Trailer Lamps
Always check all trailer lamps are
working at the beginning of each
trip, and periodically on longer trips.
If equipped, the Trailering App will
monitor the RH turn/brake lamp
circuit, LH turn/brake lamp circuit,
running lamp circuit, and reverse
lamp circuits on the trailer. DIC
messages and Trailering App alerts
may be displayed if lighting circuit
issues are detected on the trailer.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
Driving and Operating 297
adjust. Press and hold to
continuously adjust the Trailer Gain.
To turn the output to the trailer off,
adjust the Trailer Gain setting to 0.0.
This setting can be adjusted from
0.0 to 10.0 with a trailer connected
or disconnected.
TRAILER OUTPUT: This displays
anytime 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
displays.
. A trailer with electric brakes has
become disconnected, a CHECK
TRAILER WIRING message
displays on the DIC. .
There is a fault present in the
wiring to the trailer brakes, a
CHECK TRAILER WIRING
message displays on the DIC.
. The ITBC system is not working
due to a fault, a SERVICE
TRAILER BRAKE SYSTEM
message displays in the DIC.
Manual Trailer Brake Apply
Lever
Slide this lever right to apply the
trailer ’s electric brakes independent
of the vehicle’s brakes. Use this
lever to adjust Trailer Gain to
achieve proper 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
and properly connected.
Trailer Gain Adjustment
Procedure
Trailer Gain should be set for a
specific trailering condition and it
must be readjusted 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.
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 - 40 km/h
(20 - 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.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-1500-11698638) - 2019 - CRC - 5/14/19
298 Driving and Operating
2. Adjust the Trailer Gain, usingthe Trailer Gain (+) or (-)
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. Adjust the Trailer Gain
to the highest allowable setting
for the towing condition.
3. Readjust Trailer Gain anytime vehicle 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
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 in
the trailer wiring. This message
will also turn off if it is
acknowledged. To determine whether 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
continues over multiple ignition
cycles, have the vehicle serviced.
If either the CHECK TRAILER
WIRING or SERVICE TRAILER
BRAKE SYSTEM message displays