2020 GMC SIERRA DENALI ECO mode

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
222 Driving and Operating
To rock the vehicle back and forth to
get out of snow, ice, or sand without
damaging the transmission, seeIf
the Vehicle Is Stuck 0199.
N : In this position, the engine does
not connect with the wheels. To
restart the engine when the vehicle
is already moving, use
N (Neutral) only.
Also, use N (Neutral) when the
vehicle is being towed.
{Warning
Shifting into a drive gear while the
engine is running at high speed is
dangerous. Unless your foot is
firmly on the brake pedal, the
vehicle could move very rapidly.
You could lose control and hit
people or objects. Do not shift
into a drive gear while the engine
is running at high speed.
Caution
Shifting out of P (Park) or
N (Neutral) with the engine
running at high speed may
damage the transmission. The
repairs would not be covered by
the vehicle warranty. Be sure the
engine is not running at high
speed when shifting the vehicle.
Caution
A transmission or engine oil hot
message may display if the
automatic transmission fluid or
engine oil is too hot. Driving
under this condition can damage
the vehicle. Stop and idle the
engine to cool the engine oil or
automatic transmission fluid.
These messages will clear when
the engine oil or transmission
fluid has cooled sufficiently. D :
This position is for normal
driving. It provides the best fuel
economy. If more power is needed
for passing, press the accelerator
pedal down.
. When going less than about
55 km/h (35 mph), push the
accelerator pedal about
halfway down.
. When going about 55 km/h
(35 mph) or more, push the
accelerator all the way down.
By doing this, the vehicle shifts
down to the next gear and has
more power.
Use D (Drive) and Tow/Haul Mode
when towing a trailer, carrying a
heavy load, driving on steep hills,
or driving off-road. Shift the
transmission to a lower gear if the
transmission shifts too often.
Downshifting the transmission in
slippery road conditions could result
in skidding. See “Skidding”under
Loss of Control 0190.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
Driving and Operating 227
Tow/Haul Mode
The Tow/Haul Mode adjusts the
transmission shift pattern to reduce
shift cycling. This provides
increased performance, vehicle
control, and enhanced transmission
and engine cooling when driving
down steep hills or mountain
grades, when towing, or when
hauling heavy loads. SeeDriver
Mode Control 0238 to activate Tow/
Haul Mode.
For vehicles without Driver Mode
Control, press the Tow/Haul button
on the center stack. If equipped, the Stop/Start system
will become unavailable when Tow/
Haul Mode is active.
Tow/Haul Mode Grade Braking
Tow/Haul Mode Grade Braking is
only enabled while the Tow/Haul
Mode is selected and the vehicle is
not in the Range Selection Mode.
See
Manual Mode 0224. Tow/Haul
Mode Grade Braking assists in
maintaining desired vehicle speeds
when driving on downhill grades by
using the engine and transmission
to slow the vehicle.
See Towing Equipment 0296.
Drive Systems
Four-Wheel Drive
If equipped, four-wheel drive
engages the front axle for extra
traction.
Read the appropriate section for
transfer case operation before
using.
Caution
Do not drive on clean, dry
pavement in 4
mand 4n(if
equipped) for an extended period
of time. These conditions may
cause premature wear on the
vehicle’s powertrain.
Driving on clean, dry pavement in
4
mor 4nmay:
. Cause a vibration to be felt in
the steering system.
. Cause tires to wear faster.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
230 Driving and Operating
If the transmission is not in
N (Neutral) when shift request
occurs, a DIC message displays.
The vehicle will allow 20 seconds
for the shift to occur. After this time,
a graphic in the instrument cluster
will indicate that the transfer case is
in 4
n.
Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.
If the transmission is not shifted into
N (Neutral) or the vehicle has not
slowed to 5 km/h (3 mph) within
20 seconds, the transfer case will
remain in its original state. This will
be indicated in the instrument
cluster.
With the vehicle moving less than
5 km/h (3 mph) and the transmission
in N (Neutral), attempt the shift
again. Shifting Out of 4
n
1. The vehicle must be stopped or
moving less than 5 km/h
(3 mph) with the transmission
in N (Neutral) and the ignition
on. It is best for the vehicle to
be moving
1.6 to 3.2 km/h (1 to 2 mph).
2. Press 4
m, AUTO, or 2m. The
actual 4x4 shift request is only
made after the button is
released. The 4x4 graphic will
remain flashing until the shift
request has completed. A DIC
message displays to indicate
the state of the request.
Once the 4x4 shift has
completed, the DIC message
disappears, the 4x4 graphic
stops flashing, and the current
setting is indicated.
If vehicle speed is higher when
shift request occurs, a DIC
message displays. Reduce
vehicle speed. If the transmission is not in
N (Neutral) when shift request
occurs, DIC messages will display.
The vehicle will allow 20 seconds
for this shift to occur. After this time,
a graphic in the instrument cluster
will indicate that the transfer case is
in 4
n.
Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.
If the transmission is not shifted into
N (Neutral) or the vehicle has not
slowed to 5 km/h (3 mph) within
20 seconds, the transfer case will
remain in its original state. This will
be indicated in the instrument
cluster.
With the vehicle moving less than
5 km/h (3 mph), and the
transmission in N (Neutral), attempt
the shift again.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
238 Driving and Operating
If HDC is to be used for more than
three minutes or on grades steeper
than 25%, the transfer case should
be put into Four-Wheel Drive Low
(4
n) to reduce the possibility of
brake overheating.
Noise from the Electronic Brake
Control Module (EBCM) is normal
when HDC is active.
When HDC is activated, the initial
HDC speed is set to the current
driving speed. It can be increased or
decreased by pressing +RES or
SET- on the steering wheel, or by
applying the accelerator or brake
pedal. This adjusted speed
becomes the new set speed.
HDC will remain enabled between
30 and 60 km/h (19 and 37 mph);
however, vehicle speed cannot be
set or maintained in this range. HDC
will automatically disable if the
vehicle speed is above 80 km/h
(50 mph) or above 60 km/h
(37 mph) for at least 30 seconds.
5must be pressed again to
re-enable HDC. HDC may disable
after an extended period of use. If this happens, HDC will require
time to cool down. The length of
time HDC remains active depends
on road conditions, grade, set
speed, vehicle loading, and outside
temperature.
When enabled, if the vehicle speed
is above 30 km/h (19 mph) and
below 60 km/h (37 mph), a DIC
message will display.
Driver Mode Control
This feature adds a sportier feel,
provides a more comfortable ride,
or assists in different weather
conditions or terrain. Depending on
the option package, available
features, and mode selected; the
suspension, steering, and
powertrain will change settings to
achieve the desired mode
characteristics. If the vehicle is
equipped with magnetic ride control,
selecting the various Driver Modes
enhances the ride performance for
the road conditions and the
selected mode.
Mode availability is dependent upon
vehicle trim level, region, and
optional features.
Not all drive modes are available
on. 1500 series vehicles may have
Normal, Sport, Off Road, Terrain,
and Tow Haul. 2500/3500 series
vehicles may have Normal, Off
Road, and Tow/Haul.
Mode Activation
To activate and deactivate Tow/Haul
turn the Drive Mode knob to the left.
For activation of modes other than
Tow/Haul, turn the Drive Mode knob
to the right.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
240 Driving and Operating
StabiliTrak/Electronic Stability
Control (ESC), the Antilock Brake
System (ABS), and the Traction
Control System (TCS) will change
for optimal off-road performance.
Use this mode for public off-road
recreational driving. SeeOff-Road
Driving 0191.
When selected, the Off-Road Mode
indicator light displays in the
instrument cluster.
_Tow/Haul Mode : This feature
assists when pulling a heavy trailer
or a heavy load. See Tow/Haul
Mode 0227.
Tow/Haul Mode is designed to be
most effective when the vehicle and
trailer combined weight is at least
75% of the vehicle’s Gross
Combined Weight Rating (GCWR).
See “Weight of the Trailer” under
Trailer Towing 0292.
Tow/Haul Mode is most useful when
pulling a heavy trailer or a heavy
load under the following conditions:
. Through rolling terrain
. In stop-and-go traffic .
In busy parking lots where
improved low speed control of
the vehicle is desired
Operating the vehicle in Tow/Haul
Mode when lightly loaded or with no
trailer at all will not cause damage.
However, there is no benefit to
selecting Tow/Haul Mode when the
vehicle is unloaded. Such a
selection when unloaded may result
in unpleasant engine and
transmission driving characteristics,
heavy or light steering, and reduced
fuel economy.
When selected, the Tow/Haul Mode
light will display in the instrument
cluster.
If the vehicle is turned off with Tow/
Haul Mode active and then restarted
within four hours or less, Tow/Haul
will remain active. Otherwise the
vehicle will start in Normal Mode.
gTerrain Mode : Use for finer
control during low speed, off-road
driving. When using this mode it will
mimic the characteristics of
four-wheel-drive low (4
n) without
the torque capabilities. Use when:
.
Traveling on very rough roads at
very low speeds, such as a
two-track or heavily rutted road.
. Traveling slowly in grassy fields.
. Pulling a boat out of the water
on a trailer.
. Using the vehicle for public
off-road recreational driving. See
Off-Road Driving 0191 and
Hill and Mountain Roads 0197.
When in Terrain Mode, the vehicle
will shift automatically but may hold
a lower gear longer to maximize
engine torque. The steering will
change to provide more precise
control. A unique pedal map,
transmission shift pattern, and rpm
control are utilized to give better
control at lower speeds and over
rough terrain. When the vehicle
comes to a stop, Vehicle Hold is
engaged. TCS will be optimized for
maximum torque transfer across
axles, and Active Braking During Lift
Throttle will be engaged.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
282 Driving and Operating
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
System Treatment Plus−Gasoline to
the vehicle’s gasoline fuel tank at
every oil change or 15 000 km
(9,000 mi), whichever occurs first.
TOP TIER Detergent Gasoline and
ACDelco Fuel System Treatment
Plus−Gasoline will help keep your
vehicle’s engine fuel deposit free
and performing optimally.
E85 or FlexFuel
Vehicles with a yellow fuel sticker
on the fuel door can use either
unleaded gasoline or fuel containing
up to 85% ethanol (E85). All other
vehicles should use only the
unleaded gasoline as described in
Recommended Fuel (Except 6.2L
V8 Engine) 0280 or
Recommended Fuel (6.2L
V8 Engine) 0281. The use of E85 or FlexFuel is
encouraged when the vehicle is
designed to use it. E85 or FlexFuel
is made from renewable sources.
To help locate fuel stations that
carry E85 or FlexFuel, the U.S.
Department of Energy has an
alternative fuel website. See
www.afdc.energy.gov/afdc/locator/
stations.
E85 or FlexFuel should meet ASTM
Specification D 5798 or CAN/
CGSB–3.512 in Canada. Do not use
the fuel if the ethanol content is
greater than 85%. Fuel mixtures that
do not meet ASTM or CGSB
specifications can affect driveability
and could cause the malfunction
indicator lamp to come on.
The starting characteristics of E85
or FlexFuel make it unsuitable for
use when temperatures fall below
−18 °C (0 °F). Use gasoline or add
gasoline to the E85 or FlexFuel.
Because E85 or FlexFuel has less
energy per liter (gallon) than
gasoline, the vehicle will need to be refilled more often. See
Filling the
Tank (Pickup Model) 0283 or
Filling the Tank (Chassis Cab
Model) 0285.
The only GM approved aftermarket
additive is ACDelco Fuel System
Treatment Plus-FlexFuel. Follow the
instructions on the bottle for proper
use. This product is available at
your GM dealer.
Caution
Some additives are not
compatible with E85 or FlexFuel
and can harm the vehicle's fuel
system. Use only additives
approved by GM for E85 or
FlexFuel vehicles. Damage
caused by unapproved additives
would not be covered by the
vehicle warranty.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
Driving and Operating 285
Filling the Tank (Chassis
Cab Model)
If the vehicle has a diesel engine,
see the Duramax diesel
supplement.
An arrow on the fuel gauge
indicates which side of the vehicle
the fuel door is on. SeeFuel Gauge
0 131.
{Warning
Fuel vapors and fuel fires burn
violently and can cause injury or
death.
Follow these guidelines 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.
(Continued)
Warning (Continued)
.Do not leave the fuel pump
unattended.
. Avoid using electronic
devices while refueling.
. Do not re-enter the vehicle
while pumping fuel.
. Keep children away from
the fuel pump and never let
children pump fuel.
. Before touching the fill
nozzle, touch a metallic
object to discharge static
electricity from your body.
. 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. Turn the fuel cap counterclockwise
to remove. Fully insert and latch the
fill nozzle, begin fueling. 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.
{Warning
Overfilling the fuel tank by more
than three clicks of a standard fill
nozzle may cause:
. Vehicle performance issues,
including engine stalling and
damage to the fuel system.
. Fuel spills.
. Under certain conditions,
fuel fires.
Be careful not to spill fuel. Wait
five seconds after you have finished
pumping before removing the fill
nozzle. Clean fuel from painted
surfaces as soon as possible. See
Exterior Care 0429. Reinstall the
cap by turning it clockwise until it
clicks.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
288 Driving and Operating
.Vehicles can tow in D (Drive).
Tow/Haul Mode is recommended
for heavier trailers. See Tow/
Haul Mode 0227. If the
transmission downshifts too
often, a lower gear may be
selected using Manual Mode.
See Manual Mode 0224.
If equipped, the following driver
assistance features should be
turned off when towing a trailer:
. Adaptive Cruise Control (ACC)
. Super Cruise Control
. Lane Keep Assist (LKA)
. Park Assist
. Automatic Parking Assist (APA)
. Reverse Automatic
Braking (RAB)
If equipped, the following driver
assistance features should be
turned to alert or off when towing a
trailer:
. Automatic Emergency
Braking (AEB)
. Intelligent Brake Assist (IBA) .
Front Pedestrian Braking (FPB)
If equipped with Lane Change Alert
(LCA), 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.
If equipped with Rear Cross Traffic
Alert (RCTA), use caution while
backing up when towing a trailer, as
the RCTA detection zones that
extend out from the back of the
vehicle do not move further back
when a trailer is towed.
{Warning
To prevent serious injury or death
from carbon monoxide (CO),
when towing a trailer: . Do not drive with the
liftgate, trunk/hatch,
or rear-most window open.
(Continued)
Warning (Continued)
.Fully open the air outlets on
or under the instrument
panel.
. Adjust the climate control
system to a setting that
brings in only outside air.
See “Climate Control
Systems” in the Index.
For more information about
carbon monoxide, see Engine
Exhaust 0220.
Towing a trailer requires experience.
The combination of the vehicle and
trailer is longer and not as
responsive as the vehicle itself. Get
used to the handling and braking of
the combination by driving on a
level road surface before driving on
public roads.
The trailer structure, the tires, and
the brakes must all be rated to carry
the intended cargo. Inadequate
trailer equipment can cause the
combination to operate in an