change time GMC SIERRA 2020 User Guide

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Lighting 165
Lighting
Exterior Lighting
Exterior Lamp Controls . . . . . . . 165
Exterior Lamps OffReminder . . . . . . . . . . . . . . . . . . . 167
Headlamp High/Low-Beam Changer . . . . . . . . . . . . . . . . . . . . 167
Flash-to-Pass . . . . . . . . . . . . . . . . 168
Daytime Running Lamps (DRL) . . . . . . . . . . . . . . . 168
Automatic Headlamp System . . . . . . . . . . . . . . . . . . . . . . 168
Hazard Warning Flashers . . . . . 169
Turn and Lane-Change Signals . . . . . . . . . . . . . . . . . . . . . . 170
Fog Lamps . . . . . . . . . . . . . . . . . . . 170
Task Lighting . . . . . . . . . . . . . . . . . 171
Exterior Cargo Lamps . . . . . . . . 171
Interior Lighting
Instrument Panel Illumination Control . . . . . . . . . . . . . . . . . . . . . . 172
Dome Lamps . . . . . . . . . . . . . . . . . 172
Reading Lamps . . . . . . . . . . . . . . 173
Lighting Features
Entry Lighting . . . . . . . . . . . . . . . . 173
Exit Lighting . . . . . . . . . . . . . . . . . . 173 Battery Load Management . . . 174
Battery Power Protection . . . . . 174
Exterior Lighting Battery
Saver . . . . . . . . . . . . . . . . . . . . . . . 174
Exterior Lighting
Exterior Lamp Controls
The exterior lamp control is on the
instrument panel to the left of the
steering wheel.
O: Turns off the automatic
headlamps and Daytime Running
Lamps (DRL). Turn the headlamp
control to
Oagain to turn the
automatic headlamps or DRL
back on.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Lighting 169
There is a light sensor on top of the
instrument panel. Do not cover the
sensor, otherwise the headlamps
will come on when they are not
needed.
The system may also turn on the
headlamps when driving through a
parking garage or tunnel.
If the vehicle is started in a dark
garage, the automatic headlamp
system comes on immediately. If it
is light outside when the vehicle
leaves the garage, there is a slight
delay before the automatic
headlamp system changes to the
Daytime Running Lamps (DRL).
During that delay, the instrumentcluster may not be as bright as
usual. Make sure the instrument
panel illumination control is in the
full bright position. See
Instrument
Panel Illumination Control 0172.
When it is bright enough outside,
the headlamps will turn off or may
change to DRL.
The automatic headlamp system
turns off when the exterior lamp
control is turned to
Oor the ignition
is off.
Lights On with Wipers
If the windshield wipers are
activated in daylight with the engine
on, and the exterior lamp control is
in AUTO, the headlamps, parking
lamps, and other exterior lamps
come on. The transition time for the
lamps coming on varies based on
wiper speed. When the wipers are
not operating, these lamps turn off.
Move the exterior lamp control to
O
or;to disable this feature.
Hazard Warning Flashers
|: Press this button to make the
front and rear turn signal lamps
flash on and off. Press again to turn
the flashers off.
When the hazard warning flashers
are on, the vehicle's turn signals will
not work.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
170 Lighting
Turn and Lane-Change
Signals
An arrow on the instrument cluster
flashes in the direction of the turn or
lane change.
Move the turn signal lever all the
way up or down to signal a turn.
Partially raise or lower the lever for
less than one second until the arrow
starts to flash to signal a lane
change. This causes the turn
signals to automatically flash three
times. It will flash six times if Tow/
Haul Mode is active. Holding the
turn signal lever for more than
one second will cause the turn
signals to flash until the lever is
released.The lever returns to its starting
position whenever it is released.
If after signaling a turn or a lane
change the arrows flash rapidly or
do not come on, a signal bulb could
be burned out. If equipped with LED
turn signals, see your dealer.
Replace any burned out bulbs. If a
bulb is not burned out, check the
fuse. See
Fuses and Circuit
Breakers 0370.
Turn Signal On Chime
If the turn signal is left on for more
than 1.2 km (0.75 mi), a chime
sounds at each flash of the turn
signal. A message may appear in
the Driver Information Center (DIC).
See Vehicle Messages 0156. To
turn the chime and message off,
move the turn signal lever to the off
position.
Fog Lamps
If equipped, the fog lamp control is
near the exterior lamp control to the
left of the steering column.
The ignition must be on for the fog
lamps to come on.
#: Press to turn the fog lamps on
or off. A light will come on in the
instrument cluster.
When the fog lamps are turned on,
the parking lamps automatically
turn on.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
174 Lighting
The exterior lamps and dome lamp
remain on for a set amount of time,
then automatically turn off.
The exterior lamps turn off
immediately by turning the exterior
lamp control off.
This feature can be changed. See
Vehicle Personalization0157.
Battery Load
Management
The vehicle has Electric Power
Management (EPM), which
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. The voltmeter
gauge or the voltage display on the
Driver Information Center (DIC),
if equipped, may show the voltage moving 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 the
power that is 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 and it is recommended
that the driver reduce the electrical
loads as much as possible.
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.
Exterior Lighting Battery
Saver
The exterior lamps turn off about
10 minutes after the ignition is
turned off, if the parking lamps or
headlamps have been manually left
on. This protects against draining
the battery. To restart the 10-minute

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
178 Climate Controls
Air Delivery Mode Controls :
Press
z,Y, or[to change the
direction of the airflow. Any
combination of the three controls
can be selected. An indicator light
comes on in the selected mode
button.
To change the current mode, select
one or more of the following. An
indicator light will illuminate:
z: Air is directed to the
windshield, outboard a/c outlets,
and side window outlets.
Y: Air is directed to the a/c outlets.
[:Air is directed to the floor
outlets, with some air directed to the
windshield, outboard a/c outlets,
and side window outlets.
0MAX : Air is directed to the
windshield and the fan runs at a
higher speed if not already above a
medium fan speed. This mode
overrides the previous mode
selected and clears fog or frost from
the windshield more quickly. When the control is pressed again, the
system returns to the previous mode
setting and fan speed.
For best results, clear all snow and
ice from the windshield before
defrosting.
@:
Press to turn on recirculation.
An indicator light comes on. Air is
recirculated to quickly cool the
inside of the vehicle. It can also be
used to help reduce outside air and
odors that enter the vehicle.
Avoid using recirculation for long
periods of time in cold or damp
conditions. Using recirculation in
cold or damp conditions can result
in window fogging.
A/C : Press to turn the air
conditioning on or off. An indicator
light comes on to show that the air
conditioning is enabled. If the fan is
turned off, the air conditioner will not
run. The A/C light will stay on even
if the outside temperatures are
below freezing.
Rear Window Defogger
1REAR : If equipped, press to
turn the rear window defogger on or
off. An indicator light on the button
comes on to show that the rear
window defogger is on.
The rear window defogger only
works when the engine is running.
The defogger turns off if the ignition
is turned off or to ACC/
ACCESSORY.
If equipped with heated outside
mirrors, press
fto turn them on or
off. See Heated Mirrors 044.
Caution
Using a razor blade or sharp
object to clear the inside rear
window can damage the rear
window defogger. Repairs would
not be covered by the vehicle
warranty. Do not clear the inside
rear window with sharp objects.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Climate Controls 181
or passenger side temperature
display shows the temperature
setting increasing or decreasing.
SYNC :Press to link the passenger
temperature setting to the driver
setting. The SYNC indicator light will
turn on. When the passenger setting
is adjusted, the SYNC indicator light
will turn off.
Air Delivery Mode Control : Press
z,Y, or[to change the
direction of the airflow. Any
combination of the three controls
can be selected. An indicator light
comes on in the selected mode
button.
Changing the mode cancels the
automatic operation and the system
goes into manual mode. Press
AUTO to return to automatic
operation.
To change the current mode, select
one or more of the following:
z: Air is directed to the
windshield, outboard a/c outlets,
and side window outlets.
Y: Air is directed to the a/c outlets.
[:Air is directed to the floor
outlets, with some air directed to the
windshield, outboard a/c outlets,
and side window outlets.
0MAX : Air is directed to the
windshield and the fan runs at a
higher speed if not already above a
medium fan speed. This mode
overrides the previous mode
selected and clears fog or frost from
the windshield more quickly. When
the control is pressed again, the
system returns to the previous mode
setting and fan speed.
For best results, clear all snow and
ice from the windshield before
defrosting.
@: Press to turn on recirculation.
An indicator light comes on. Air is
recirculated to quickly cool the
inside of the vehicle. It can also be
used to help reduce outside air and
odors that enter the vehicle. Avoid using recirculation for long
periods of time in cold or damp
conditions. Using recirculation in
cold or damp conditions can result
in window fogging.
A/C :
Press to turn the air
conditioning on or off. An indicator
light comes on to show that the air
conditioning is enabled. If the fan is
turned off, the air conditioner will not
run. The A/C light will stay on even
if the outside temperatures are
below freezing.
Rear Window Defogger
1REAR : If equipped, press to
turn the rear window defogger on or
off. An indicator light on the button
comes on to show that the rear
window defogger is on.
The rear window defogger only
works when the engine is running.
The defogger turns off if the ignition
is turned off or to ACC/
ACCESSORY.
If equipped with heated outside
mirrors, press
fto turn them on or
off. See Heated Mirrors 044.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
186 Driving and Operating
Lane Change Alert (LCA) . . . . . 274
Lane Departure Warning(LDW) (2500/3500
Series) . . . . . . . . . . . . . . . . . . . . . . 276
Lane Keep Assist (LKA) (1500
Series) . . . . . . . . . . . . . . . . . . . . . . 278
Fuel
Top Tier Fuel . . . . . . . . . . . . . . . . . 280
Recommended Fuel (Except6.2L V8 Engine) . . . . . . . . . . . . . 280
Recommended Fuel (6.2L V8 Engine) . . . . . . . . . . . . . . . . . . 281
Prohibited Fuels . . . . . . . . . . . . . . 281
Fuels in Foreign Countries . . . 281
Fuel Additives . . . . . . . . . . . . . . . . 282
E85 or FlexFuel . . . . . . . . . . . . . . 282
Filling the Tank (Pickup Model) . . . . . . . . . . . . . . . . . . . . . . 283
Filling the Tank (Chassis Cab Model) . . . . . . . . . . . . . . . . . . . . . . 285
Filling a Portable Fuel Container . . . . . . . . . . . . . . . . . . . 286
Trailer Towing
General TowingInformation . . . . . . . . . . . . . . . . . . 287
Driving Characteristics and Towing Tips . . . . . . . . . . . . . . . . . 287
Trailer Towing . . . . . . . . . . . . . . . . 292
Towing Equipment . . . . . . . . . . . . 296 Trailer Sway Control (TSC) . . . 308
Trailering App . . . . . . . . . . . . . . . . 310
Conversions and Add-Ons
Add-On Electrical
Equipment . . . . . . . . . . . . . . . . . . 322
Adding a Snow Plow or Similar Equipment . . . . . . . . . . . . . . . . . . 323
Pickup Conversion to Chassis Cab . . . . . . . . . . . . . . . . 326
Driving Information
Driving for Better Fuel
Economy
Driving habits can affect fuel
mileage. Here are some driving tips
to get the best fuel economy
possible:
. Set the climate controls to the
desired temperature after the
engine is started, or turn them
off when not required.
. Avoid fast starts and accelerate
smoothly.
. Brake gradually and avoid
abrupt stops.
. Avoid idling the engine for long
periods of time.
. When road and weather
conditions are appropriate, use
cruise control.
. Always follow posted speed
limits or drive more slowly when
conditions require.
. Keep vehicle tires properly
inflated.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 231
Shifting Into N (Neutral)
To shift into N (Neutral):1. Start the vehicle.
2. Shift the transmission to N (Neutral).
3. Shift the transfer case to 2
m.
4. Apply the parking brake and/or brake pedal.
5. Press 2
mfive times in
10 seconds until the N (Neutral)
graphic starts flashing in the
instrument cluster. When the
shift is complete, the graphic
stops flashing. If the parking
brake and/or brake pedal is not
applied within 20 seconds, the
transfer case will remain in the
original state.
6. 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. Shifting Out of N (Neutral)
To shift out of N (Neutral):
1. Turn the ignition on with the engine off. See Ignition
Positions (Keyless Access)
0 208 or
Ignition Positions (Key Access)
0 210.
2. Set the parking brake. See Electric Parking Brake 0233.
3. Shift the transmission to N (Neutral).
4. Shift the transfer case to 2
m.
Transfer case shifts out of
N (Neutral) can only be made
into 2
m. When the shift to 2mis
complete, the graphic in the
instrument cluster will stop
flashing. If the transfer case
cannot complete a shift, the
graphic will return to the
previously selected setting. Single Speed Transfer Case
If equipped, the transfer case
controls are used to shift into and
out of four-wheel drive.
To shift the transfer case, press the
desired button. The graphic in the
instrument cluster will flash while a
shift is in progress. The graphic
displayed will change to indicate the
setting requested.
When the shift is complete the
graphic will stop flashing. The DIC
message turns off once the shift is
complete. If the transfer case

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
232 Driving and Operating
cannot complete a shift request, it
will go back to its last chosen
setting.
The settings are:
2
m(Two-Wheel Drive High) :Use
for driving on most streets and
highways. The front axle is not
engaged. This setting provides the
best fuel economy.
4
m(Four-Wheel Drive High) : Use
this setting when extra traction is
needed, such as when driving on
snowy or icy roads, when
off-roading, or when plowing snow.
AUTO (Automatic Four-Wheel
Drive)
Use when road surface conditions
are variable. When driving in AUTO,
the front axle is engaged, and the
vehicle's power is sent to the front
and rear wheels automatically
based on driving conditions. This
setting provides slightly lower fuel
economy than 2
m. Shifts between 2
m, 4m, and AUTO
Any of these shifts can be made at
normal driving speed.
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.
Once the 4x4 shift has completed,
the DIC message disappears, the
4x4 graphic stops flashing, and the
current setting is indicated.
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. Once the
4x4 shift has completed, the DIC
message disappears, the 4x4
graphic stops flashing, and the
current setting is indicated.Brakes
Electric Brake Boost
Vehicles equipped with electric
brake boost have hydraulic brake
circuits that are electronically
controlled when the brake pedal is
applied during normal operation.
The system performs routine tests
and turns off within a few minutes
after the vehicle is shutdown. Noise
may be heard during this time. If the
brake pedal is pressed during the
tests or when the electric brake
boost system is off, a noticeable
change in pedal force and travel
may be felt. This is normal.
Antilock Brake
System (ABS)
The Antilock Brake System (ABS)
helps prevent a braking skid and
maintain steering while
braking hard.
ABS performs a system check when
the vehicle is first driven.
A momentary motor or clicking noise

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 233
may be heard while this test is going
on, and the brake pedal may move
slightly. This is normal.
If there is a problem with ABS, this
warning light stays on. SeeAntilock
Brake System (ABS) Warning Light
0 141.
ABS does not change the time
needed to get a foot on the brake
pedal and does not always
decrease stopping distance. If you
get too close to the vehicle ahead,
there will not be enough time to
apply the brakes if that vehicle
suddenly slows or stops. Always
leave enough room ahead to stop,
even with ABS.
Using ABS
Do not pump the brakes. Just hold
the brake pedal down firmly.
Hearing or feeling ABS operate is
normal.
Braking in Emergencies
ABS allows steering and braking at
the same time. In many
emergencies, steering can help
even more than braking.
Electric Parking Brake
The vehicle has an Electric Parking
Brake (EPB). The EPB can always
be activated, even if the ignition is off. To prevent draining the battery,
avoid repeated cycles of the EPB
when the engine is not running.
The system has a
Yor PARK
Electric Parking Brake light, and a
8
Service Parking Brake light. See
Electric Parking Brake Light 0141
and
Service Electric Parking Brake Light
0 141. There are also parking
brake-related Driver Information
Center (DIC) messages.
Before leaving the vehicle, check for
the
Yor PARK light to ensure that
the parking brake is applied.
EPB Apply
To apply the EPB:
1. Be sure the vehicle is at a complete stop.
2. Press the EPB switch momentarily.
The
Yor PARK light will flash and
then stay on once the EPB is fully
applied. If the
Yor PARK light
flashes continuously, then the EPB