2020 GMC YUKON ignition

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 209
away from moving engine
parts. If you do not, it could be
damaged.
The length of time the heater should
remain plugged in depends on
several factors. Ask a dealer in the
area where you will be parking the
vehicle for the best advice on this.
Retained Accessory
Power (RAP)
When the ignition is turned from on
to off, the following features (if
equipped) will continue to function
for up to 10 minutes, or until the
driver door is opened. These
features will also work when the
ignition is in RUN or ACC/
ACCESSORY:
. Infotainment System
. Power Windows (during RAP
this functionality will be lost
when any door is opened)
. Sunroof (during RAP this
functionality will be lost when
any door is opened)
. Auxiliary Power Outlet .
Audio System
. OnStar System
Shifting Into Park
{Warning
It can be dangerous to get out of
the vehicle if the shift lever is not
fully in P (Park) with the parking
brake firmly set. The vehicle can
roll. If you have left the engine
running, the vehicle can move
suddenly. You or others could be
injured. To be sure the vehicle will
not move, even when you are on
fairly level ground, use the steps
that follow. If the vehicle has a
four-wheel-drive transfer case
with an N (Neutral) position, and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). Be sure the transfer
case is in a drive gear. If towing a
trailer, see Driving Characteristics
and Towing Tips 0259. 1. Hold the brake pedal down,
then set the parking brake. See
Parking Brake 0225.
2. Move the shift lever into the P (Park) position by pulling the
shift lever toward you and
moving it up as far as it will go.
3. Be sure the transfer case is in a drive gear –not in
N (Neutral).
4. Push the ignition key in, towards the steering column
and then turn the ignition off.
5. Remove the key and take it with you. If you can leave the
vehicle with the ignition key in
your hand, the vehicle is in
P (Park).
Leaving the Vehicle with the
Engine Running
{Warning
It can be dangerous to leave the
vehicle with the engine running.
The vehicle could move suddenly
(Continued)

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
210 Driving and Operating
Warning (Continued)
if the shift lever is not fully in
P (Park) with the parking brake
firmly set.
If you have four-wheel drive and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). So be sure the transfer
case is in a drive gear–not in
N (Neutral).
And, if you leave the vehicle with
the engine running, it could
overheat and even catch fire. You
or others could be injured. Do not
leave the vehicle with the engine
running unless you have to.
If you have to leave the vehicle with
the engine running, be sure the
vehicle is in P (Park) and the
parking brake is firmly set before
you leave it. After you move the shift
lever into P (Park), hold the regular
brake pedal down. Then, see if you
can move the shift lever away from P (Park) without first pulling it toward
you. If you can, it means that the
shift lever was not fully locked into
P (Park).
Torque Lock
If you are parking on a hill and you
do not shift the transmission into
P (Park) properly, the weight of the
vehicle may put too much force on
the parking pawl in the
transmission. You may find it difficult
to pull the shift lever out of P (Park).
This is called torque lock. To
prevent torque lock, set the parking
brake and then shift into P (Park)
properly before you leave the
driver seat.
When you are ready to drive, move
the shift lever out of P (Park) before
you release the parking brake.
If torque lock does occur, you may
need to have another vehicle push
yours a little uphill to take some of
the pressure from the parking pawl
in the transmission. You will then be
able to pull the shift lever out of
P (Park).
Shifting out of Park
This vehicle is equipped with an
electronic shift lock release system.
The shift lock release system is
designed to prevent movement of
the shift lever out of P (Park), unless
the ignition is on and the brake
pedal is applied.
The shift lock release is always
functional except in the case of an
uncharged or low voltage (less than
9 volt) battery.
If the vehicle has an uncharged
battery or a battery with low voltage,
try charging or jump starting the
battery. See
Jump Starting - North
America 0360.
To shift out of P (Park): 1. Apply the brake pedal.
2. Move the shift lever to the desired position.
If you still are unable to shift out of
P (Park): 1. Ease the pressure on the shift lever.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 213
Automatic
Transmission
This vehicle has an electronic shift
lever position indicator within the
instrument cluster. This display
comes on when the ignition is on or
in service mode.
There are several different positions
for the shift lever.
See“Range Selection Mode” under
Manual Mode 0216.
P : This position locks the drive
wheels. Use P (Park) when starting
the engine because the vehicle
cannot move easily. When parked
on a hill, especially when the
vehicle has a heavy load, you might
notice an increase in the effort to shift out of P (Park). See
“Torque
Lock” under Shifting Into Park
0 209.
{Warning
It is dangerous to get out of the
vehicle if the shift lever is not fully
in P (Park) with the parking brake
firmly set. The vehicle can roll.
Do not leave the vehicle when the
engine is running. If you have left
the engine running, the vehicle
can move suddenly. You or others
could be injured. To be sure the
vehicle will not move, even when
you are on fairly level ground,
always set the parking brake and
move the shift lever to P (Park).
See Shifting Into Park 0209 and
Driving Characteristics and
Towing Tips 0259.
{Warning
If you have four-wheel drive, the
vehicle will be free to roll —even
if the shift lever is in P (Park) —if
the transfer case is in N (Neutral).
So, be sure the transfer case is in
a drive gear, Two-Wheel Drive
High or Four-Wheel Drive High or
Four-Wheel Drive Low —not in
N (Neutral). See Shifting Into Park
0 209.
R : Use this gear to back up.
Caution
Shifting to R (Reverse) while the
vehicle is moving forward could
damage the transmission. The
repairs would not be covered by
the vehicle warranty. Shift to
R (Reverse) only after the vehicle
is stopped.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 215
In some cases, this could appear to
be a delayed shift, however the
transmission is operating normally.
The transmission uses adaptive
shift controls. The adaptive shift
control process continually
compares key shift parameters to
pre-programmed ideal shifts stored
in the transmission’s computer. The
transmission constantly makes
adjustments to improve vehicle
performance according to how the
vehicle is being used, such as with
a heavy load or when the
temperature changes. During this
adaptive shift control process,
shifting might feel different as the
transmission determines the best
settings.
When temperatures are very cold,
the transmission's gear shifting
could be delayed providing more
stable shifts until the engine warms
up. Shifts could be more noticeable
with a cold transmission. This
difference in shifting is normal.L :
This position allows selection of
a range of gears appropriate for
current driving conditions.
If equipped, see “Range Selection
Mode” underManual Mode 0216.
Caution
Spinning the tires or holding the
vehicle in one place on a hill
using only the accelerator pedal
may damage the transmission.
The repair will not be covered by
the vehicle warranty. If the vehicle
is stuck, do not spin the tires.
When stopping on a hill, use the
brakes to hold the vehicle in
place.
Normal Mode Grade Braking
This mode is enabled when the
vehicle is started, but is not enabled
in Range Selection Mode. It assists
in maintaining desired vehicle
speeds when driving on downhill
grades by using the engine and
transmission to slow the vehicle. The first time the system engages
for each ignition cycle, a DIC
message will be displayed.
To disable or enable Normal Mode
Grade Braking within the current
ignition cycle, press and hold the
Tow/Haul button for five seconds.
When the button is released, the
requested mode change is made.
A DIC message displays.
For other forms of grade braking,
see
Tow/Haul Mode 0218 and
Cruise Control 0230.
Kickdown Mode
The accelerator pedal provides an
additional downshift after pressing
through the kickdown feature.
It requires extra pedal pressure near
the end of its travel to engage.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 219
To disable or enable Tow/Haul
Grade Braking within the current
ignition cycle, press and hold the
Tow/Haul button for five seconds.
When the button is released, the
requested mode change is made.
A DIC message is displayed.
SeeTowing Equipment 0270.
For other forms of grade braking,
see Automatic Transmission 0213
and
Cruise Control 0230.Drive Systems
Four-Wheel Drive
If equipped, four-wheel drive
engages the front axle for extra
traction.
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.
. Make the transfer case harder to
shift, and cause it to run noisier.
{Warning
Shifting the transfer case to
N (Neutral) can cause the vehicle
to roll even if the transmission is
in P (Park). You or someone else
could be seriously injured. Be
sure to set the parking brake
before placing the transfer case in
N (Neutral). See Parking Brake
0 225.
Caution
Extended high-speed operation in
4
nmay damage or shorten the
life of the drivetrain.
Engagement noise and bump when
shifting between 4
nand 4mor from
N (Neutral), with the engine running,
is normal.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
220 Driving and Operating
Shifting into 4nwill turn Traction
Control and StabiliTrak/Electronic
Stability Control off. See Traction
Control/Electronic Stability Control
0 226.
Two Speed Automatic
Transfer Case
If equipped, use the transfer case
knob next to the steering wheel to
shift into and out of four-wheel drive.
All of the lights will blink on then off
momentarily when the ignition
turned on. The light that remains on
will indicate the state of the
transfer case. If the indicator mark on the switch
does not match up with the light
then that likely means the switch
was moved when the ignition
was off.
The indicator mark on the switch
must line up with the indicator light
before a shift can be commanded.
To command a shift rotate the
transfer case switch to the new
desired position. The light will blink
meaning that the shift is in progress.
When the shift is completed the new
position will be illuminated. If the
transfer case cannot complete a
shift command, it will go back to its
last chosen setting.
The settings are:
N (Neutral) :
Use only when the
vehicle needs to be towed. See
Recreational Vehicle Towing 0364
or
Towing the Vehicle 0363.
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. AUTO (Automatic Four-Wheel
Drive) :
Use when road surface
traction 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.
Do not use AUTO mode,
if equipped, to park on a steep
grade with poor traction such as ice,
snow, mud, or gravel. In AUTO
mode only the rear wheels will hold
the vehicle from sliding when
parked. If parking on a steep grade,
use 4
mto keep all four wheels
engaged.
4
m(Four-Wheel Drive High) : Use
this position when extra traction is
needed, such as when driving on
snowy or icy roads, when
off-roading, or when plowing snow.
4
n(Four-Wheel Drive Low) : This
setting engages the front axle and
delivers extra torque. Choose 4
n

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
Driving and Operating 221
when driving off-road in deep sand,
deep mud, or deep snow, and while
climbing or descending steep hills.
Shifting into 4
nwill turn Traction
Control and StabiliTrak/ESC off.
See Traction Control/Electronic
Stability Control 0226.
Shifting Into 4
mor AUTO
Turn the knob to the 4
mor AUTO
position at any speed, except from 4
n. The indicator light will flash while
shifting and will remain on when the
shift is completed.
Shifting Into 2
m
Turn the knob to 2mat any speed,
except when shifting from 4
n. The
indicator light will flash while shifting
and will remain on when the shift is
completed.
Shifting Into 4
n
When 4nis engaged, keep vehicle
speed below 72 km/h (45 mph).
To shift: 1. The ignition must be on and
the vehicle must be stopped or
moving less than
5 km/h (3 mph) with the
transmission in N (Neutral). It is
best for the vehicle to be
moving
1.6 to 3.2 km/h (1 to 2 mph).
2. Turn the knob to 4
n. Wait for
the 4
nindicator light to stop
flashing before shifting the
transmission into gear.
Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.
If the transmission is in gear and/or
moving more than 5 km/h (3 mph),
the 4
nindicator light will flash for
30 seconds and not complete the
shift. After 30 seconds the transfer
case will shift to 4
m. Turn the knob to 4
mto display the indicator. 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
To shift:
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. Turn the knob to 4
m, AUTO,
or 2
m. Wait for the 4m, AUTO,
or 2
mindicator light to stop
flashing before shifting the
transmission into gear.
Caution
Shifting the transmission into gear
before the requested mode
indicator light has stopped
flashing could damage the
transfer case.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13566587) - 2020 - CRC - 4/15/19
222 Driving and Operating
If the transmission is in gear and/or
moving more than 5 km/h (3 mph),
the 4
m, AUTO, or 2mindicator light
will flash for 30 seconds but will not
complete the shift. With the vehicle
moving less than 5 km/h (3 mph),
and the transmission in N (Neutral),
attempt the shift again.
Shifting Into N (Neutral)
To shift into N (Neutral):
1. Park the vehicle on a level surface.
2. Set the parking brake and press and hold the brake
pedal. See Parking Brake
0 225.
3. Start the vehicle or turn the ignition on.
4. Shift the transmission to N (Neutral).
5. Shift the transfer case to 2
m.
6. Turn the transfer case knob clockwise to N (Neutral) until it
stops and hold it there until the
N (Neutral) light starts blinking.
This will take at least 10 seconds. Then slowly
release the knob to the 4
n
position. The N (Neutral) light
will come on when the transfer
case shift to N (Neutral) is
complete.
7. With the engine running, verify that the transfer case is in
N (Neutral) by shifting the
transmission to R (Reverse),
then shift the transmission to
D (Drive). There should be no
movement of the vehicle while
shifting the transmission.
8. Turn the engine off, and the ignition to ACC/ACCESSORY.
9. Place the transmission shift lever in P (Park). See
Recreational Vehicle Towing
0364.
10. Turn the ignition off.
Shifting Out of N (Neutral)
To shift out of N (Neutral): 1. Set the parking brake and apply the brake pedal. 2. Turn the ignition on with the
engine off.
3. Shift the transmission to N (Neutral).
4. Turn the transfer case knob to the desired setting.
After the transfer case has
shifted out of N (Neutral), the
N (Neutral) light will go out.
5. Release the parking brake.
6. Start the engine and shift the transmission to the
desired gear.