wheel GMC YUKON 2012 Workshop Manual

Black plate (31,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-31
{WARNING
It can be dangerous to get out of
the vehicle if the automatic
transmission 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 unless you
have to. 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).
{WARNING
If the vehicle has a four-wheel
drive transfer case with a
N (Neutral) position, and the
transfer case is in N (Neutral), the
vehicle may roll, even if the
automatic transmission shift lever
is in P (Park). So, be sure the
transfer case is in a drive
gear—not in N (Neutral). Always
set the parking brake.
Follow the proper steps to be sure
the vehicle will not move. See
Shifting Into Park on page 9‑27.
If parking on a hill and pulling a
trailer, see Driving Characteristics
and Towing Tips on page 9‑68.
Automatic
Transmission
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
If the vehicle is has an automatic
transmission, it has an electronic
shift position indicator within the
instrument panel cluster. This
display comes on when the ignition
key is turned to the ON/RUN
position.
There are several different positions
for the shift lever.
Heavy Duty 6-Speed Automatic
Transmission Shown (Light Duty Similar)
See “Range Selection Mode” under
Manual Mode on page 9‑35.

Black plate (32,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-32 Driving and Operating
P (Park):This position locks the
rear wheels. It is the best position to
use 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 on page 9‑27 for
more information.
{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 unless you
have to. 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,
(Continued)
WARNING (Continued)
always set the parking brake and
move the shift lever to P (Park).
SeeShifting Into Park on
page 9‑27. If you are pulling a
trailer, see Driving Characteristics
and Towing Tips on page 9‑68.
{WARNING
If the vehicle has a four-wheel
drive transfer case with a
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, Two-Wheel Drive High or
Four-Wheel Drive High or
Four-Wheel Drive Low —not in
N (Neutral). See Shifting Into Park
on page 9‑27. Always set the
parking brake. R (Reverse):
Use this gear to
back up.
Notice: 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.
To rock the vehicle back and forth to
get out of snow, ice, or sand without
damaging the transmission, see If
the Vehicle Is Stuck on page 9‑15.
N (Neutral): 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.

Black plate (34,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-34 Driving and Operating
The vehicle's transmission uses
adaptive shift controls. Adaptive
shift controls continually compares
key shift parameters to
pre-programmed ideal shifts stored
in the transmissions 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,
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.
M (Manual Mode):This position
lets drivers select the range of gears
appropriate for current driving
conditions. If the vehicle has this feature, see
“Range Selection
Mode” underManual Mode on
page 9‑35.
3 (Third): This position is also used
for normal driving. It reduces vehicle
speed more than D (Drive) without
using the brakes. You might choose
3 (Third) instead of D (Drive) when
driving on hilly, winding roads, when
towing a trailer, so there is less
shifting between gears and when
going down a steep hill.
2 (Second): This position reduces
vehicle speed even more than
3 (Third) without using the brakes.
You can use 2 (Second) on hills.
It can help control vehicle speed as
you go down steep mountain roads,
but then you would also want to use
the brakes off and on.
If you manually select 2 (Second) in
an automatic transmission, the
transmission will start in
second gear. You can use this
feature for reducing the speed of the rear wheels when you are trying to
start the vehicle from a stop on
slippery road surfaces.
1 (First):
This position reduces
vehicle speed without using the
brakes. You can use it for major/
severe downgrades and off-road
driving where the vehicle would
otherwise accelerate due to
steepness of grade. When you shift
to 1 (First) it provides the lowest
gear appropriate to the vehicle's
current road speed and continues to
downshift as the vehicle slows,
eventually downshifting to
1 (First) gear.
Notice: 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 you are stuck, do not
spin the tires. When stopping on
a hill, use the brakes to hold the
vehicle in place.

Black plate (35,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-35
Manual Mode
Range Selection Mode
(Hydra-Matic®6-Speed
Transmission)
Base Trim Shown (Uplevel Similar)
The vehicle may have a Range
Selection Mode. The Range
Selection Mode helps control the
vehicle's transmission and vehicle
speed while driving down hill or
towing a trailer by letting you select
a desired range of gears.
To use this feature, do the following:
1. Move the shift lever to M (Manual Mode). 2. Press the plus/minus buttons,
located on the steering column
shift lever, to select the desired
range of gears for the current
driving conditions.
When M (Manual Mode) is selected
a number displays next to the M,
indicating the current gear.
This number is the highest gear that
can be used. However, the vehicle
can automatically shift to lower
gears as it adjusts to driving
conditions. This means that all
gears below that number are
available. When 5 (Fifth) is selected,
1 (First) through 5 (Fifth) gears are
automatically shifted by the vehicle,
but 6 (Sixth) cannot be used until
the plus/minus button located on the
steering column lever is used to
change to the gear.
Grade Braking is not available when
Range Selection Mode is active.
See Tow/Haul Mode on page 9‑36. While using Range Selection Mode,
Cruise Control and the Tow/Haul
Mode can be used.
Notice:
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 you are stuck, do not
spin the tires. When stopping on
a hill, use the brakes to hold the
vehicle in place.
Low Traction Mode
If the vehicle has the Hydra-Matic®
6-Speed Automatic Transmission, it
has a Low Traction Mode that
assists in vehicle acceleration when
road conditions are slippery, such
as with ice or snow. While the
vehicle is at a stop, select the
second gear range using Range
Selection Mode. This will limit
torque to the wheels after it detects
wheel slip, preventing the tires from
spinning.

Black plate (37,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-37
Drive Systems
Four-Wheel Drive (Two
Speed Automatic
Transfer Case)
If the vehicle has four-wheel drive,
you can send the engine's driving
power to all four wheels for extra
traction. Read the following before
using four-wheel drive.
Notice:Driving on clean, dry
pavement in Four-Wheel Drive
High or Four-Wheel Drive Low for
an extended period of time may
cause premature wear on the
vehicle's powertrain. Do not drive
on clean, dry pavement in
Four-Wheel Drive High or
Four-Wheel Drive Low for
extended periods of time. While driving on clean dry pavement
and during tight turns, you may
experience a vibration in the
steering system.
The vehicle has StabiliTrak
®.
Shifting into Four-Wheel Drive Low
will turn Traction Control and
StabiliTrak off. See StabiliTrak
®
System on page 9‑46.
Front Axle
The front axle engages and
disengages automatically when you
shift the transfer case. Some delay
for the axle to engage or disengage
is normal.
Automatic Transfer Case
The transfer case knob is located to
the left of the instrument panel
cluster.
Use this dial to shift into and out of
four-wheel drive.
You can choose among five driving
settings:
Indicator lights in the switches show
you which setting you are in. The
indicator lights will come on briefly
when you turn on the ignition and
the last chosen setting will stay on.

Black plate (38,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-38 Driving and Operating
If the lights do not come on, you
should take the vehicle to your
dealer for service. An indicator light
will flash while shifting. It will stay on
when the shift is completed. If for
some reason the transfer case
cannot make a requested shift, it will
return to the last chosen setting.
2
m(Two-Wheel Drive High):This
setting is used for driving in most
street and highway situations. The
front axle is not engaged in
two-wheel drive. This setting also
provides the best fuel economy.
AUTO (Automatic Four-Wheel
Drive): This setting is ideal for use
when road surface traction
conditions are variable. When
driving the vehicle 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. Driving
in this mode results in slightly lower
fuel economy than Two-Wheel
Drive High. 4
m(Four-Wheel Drive High):
Use
the Four-Wheel Drive High position
when you need extra traction, such
as on snowy or icy roads or in most
off-road situations. This setting also
engages your front axle to help
drive the vehicle. This is the best
setting to use when plowing snow.
4
n(Four-Wheel Drive Low): This
setting also engages the front axle
and delivers extra torque. You may
never need this setting. It sends
maximum power to all four wheels.
You might choose Four-Wheel Drive
Low if you are driving off-road in
deep sand, deep mud, deep snow,
and while climbing or descending
steep hills.
The vehicle has StabiliTrak. Shifting
into Four-Wheel Drive Low will turn
Traction Control and StabiliTrak off.
See StabiliTrak
®System on
page 9‑46.
{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 on
page 9‑45.
N (Neutral): Shift the vehicle's
transfer case to N (Neutral) only
when towing the vehicle. See
Recreational Vehicle Towing on
page 10‑93 orTowing the Vehicle
on page 10‑93 for more information.
If the SERVICE 4 WHEEL DRIVE
message stays on, you should take
the vehicle to your dealer for
service. See “SERVICE 4 WHEEL
DRIVE” message under
Transmission Messages on
page 5‑45.

Black plate (39,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-39
Shifting Into Four-Wheel Drive
High or AUTO (Automatic
Four-Wheel Drive)
Turn the knob to the Four-Wheel
Drive High or AUTO position. This
can be done at any speed, except
when shifting from Four-Wheel
Drive Low. The indicator light will
flash while shifting. It will remain on
when the shift is completed.
Shifting Into Two-Wheel
Drive High
Turn the knob to the Two-Wheel
Drive High position. This can be
done at any speed, except when
shifting from Four-Wheel Drive Low.
See“Shifting Out of Four-Wheel
Drive Low” in this section for more
information. Shifting Into Four-Wheel
Drive Low
When Four-Wheel Drive Low is
engaged, vehicle speed should be
kept below 72 km/h (45 mph).
Extended high-speed operation
in 4L may damage or shorten the life
of the drivetrain.
To shift to the Four-Wheel Drive
Low position, the ignition must be in
ON/RUN and the vehicle must be
stopped or moving less than 5 km/h
(3 mph) with the transmission in
N (Neutral). The preferred method
for shifting into Four-Wheel Drive
Low is to have the vehicle moving
1.6 to 3.2 km/h (1 to 2 mph). Turn the
knob to the Four-Wheel Drive Low
position. You must wait for the
Four-Wheel Drive Low indicator light
to stop flashing and remain on
before shifting the transmission
into gear.Notice:
Shifting the transmission
into gear before the requested
mode indicator light has stopped
flashing could damage the
transfer case. To help avoid
damaging the vehicle, always wait
for the mode indicator lights to
stop flashing before shifting the
transmission into gear.
The vehicle may have significant
engagement noise and bump when
shifting between Four-Wheel Drive
Low and Four-Wheel Drive High
ranges or from N (Neutral) while the
engine is running.
If the knob is turned to the
Four-Wheel Drive Low position
when the vehicle is in gear and/or
moving more than 5 km/h (3 mph),
the Four-Wheel Drive Low indicator
light will flash for 30 seconds and
not complete the shift. After
30 seconds the transfer case
will shift to Four-Wheel Drive
High mode. With the vehicle moving
less than 5 km/h (3 mph) and the
transmission in N (Neutral), attempt
the shift again.

Black plate (40,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-40 Driving and Operating
Shifting Out of Four-Wheel
Drive Low
To shift from Four-Wheel Drive Low
to Four-Wheel Drive High, AUTO,
or Two-Wheel Drive High, the
vehicle must be stopped or moving
less than 5 km/h (3 mph) with the
transmission in N (Neutral) and the
ignition in ON/RUN. The preferred
method for shifting out of
Four-Wheel Drive Low is to have
your vehicle moving 1.6 to 3.2 km/h
(1 to 2 mph). Turn the knob to the
Four-Wheel Drive High, AUTO,
or Two-Wheel Drive High position.
You must wait for the Four-Wheel
Drive High, AUTO, or Two-Wheel
Drive High indicator light to stop
flashing and remain on before
shifting the transmission into gear.
Notice:Shifting the transmission
into gear before the requested
mode indicator light has stopped
flashing could damage the transfer case. To help avoid
damaging the vehicle, always wait
for the mode indicator lights to
stop flashing before shifting the
transmission into gear.
The vehicle may have significant
engagement noise and bump when
shifting between Four-Wheel Drive
Low and Four-Wheel Drive High
ranges or from N (Neutral) while the
engine is running.
If the knob is turned to the
Four-Wheel Drive High, AUTO,
or Two-Wheel Drive High switch
position when the vehicle is in gear
and/or moving more than 5 km/h
(3 mph), the Four-Wheel Drive High,
AUTO, or Two-Wheel Drive High
indicator 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 is in N (Neutral),
attempt the shift again.Shifting into Neutral
To shift the transfer case to
N (Neutral) do the following:
1. Make sure the vehicle is parked
so that it will not roll.
2. Set the parking brake and apply the regular brake pedal. See
Parking Brake on page 9‑45 for
more information.
3. Start the vehicle or turn the ignition to ON/RUN.
4. Put the transmission in N (Neutral).
5. Shift the transfer case to Two-Wheel Drive High.

Black plate (41,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-41
6. Turn the transfer case dialclockwise 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 dial to the Four‐Wheel Drive
Low position. The N (Neutral)
light will come on when the
transfer case shift to N (Neutral)
is complete.
7. If the engine is running, verify that the transfer case is in
N (Neutral) by shifting the
transmission to R (Reverse) for
one second, then shift the
transmission to D (Drive) for
one second.
8. Turn the ignition to ACC/ ACCESSORY, which will turn the
engine off. 9. Place the transmission shift
lever in P (Park).
10. Release the parking brake prior to moving the vehicle.
11. Turn the ignition to LOCK/OFF.
Shifting Out of Neutral
To shift out of N Neutral do the
following:
1. Set the parking brake and apply the regular brake pedal.
2. Turn the ignition to ON/RUN with the engine off, and shift the
transmission to N (Neutral).
3. Turn the transfer case dial to the desired transfer case shift
position (Two-Wheel Drive High,
Four-Wheel Drive High,
or AUTO).
After the transfer case has
shifted out of N (Neutral), the
N (Neutral) light will go out. 4. Release the parking brake prior
to moving the vehicle.
Notice: Shifting the transmission
into gear before the Four-Wheel
Drive Low indicator light has
stopped flashing could damage
the transfer case. To help avoid
damaging the vehicle, always wait
for the Four-Wheel Drive Low
indicator light to stop flashing
before shifting the transmission
into gear.
5. Start the engine and shift the transmission to the desired
position.
Excessively shifting the transfer
case into or out of the different
modes may cause the transfer case
to enter the shift protection mode.
This will protect the transfer case
from possible damage and will only
allow the transfer case to respond to
one shift per 10 seconds. The
transfer case may stay in this mode
for up to three minutes.

Black plate (42,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-42 Driving and Operating
Four-Wheel Drive
(Single Speed Automatic
Transfer Case)
If the vehicle has four-wheel drive,
you can send the engine's driving
power to all four wheels for extra
traction. Read the following before
using four-wheel drive.
Notice:Driving on clean, dry
pavement in Four-Wheel Drive
High for an extended period of
time may cause premature wear
on the vehicle's powertrain. Do
not drive on clean, dry pavement
in Four-Wheel Drive High for
extended periods of time.
While driving on clean dry pavement
and during tight turns, you may
experience a vibration in the
steering system.
Front Axle
The front axle engages and
disengages automatically when you
shift the transfer case. Some delay
for the axle to engage or disengage
is normal.
Automatic Transfer Case
The transfer case knob is located to
the left of the instrument panel
cluster.
Use this dial to shift into and out of
four-wheel drive. The vehicle has Four-Wheel Drive
with StabiliTrak
®. For information on
StabiliTrak, see StabiliTrak®System
on page 9‑46.
You can choose among three
driving settings:
Indicator lights in the switch show
you which setting you are in. The
indicator lights will come on briefly
when you turn on the ignition and
the last chosen setting will stay on.
If the lights do not come on, you
should take the vehicle to your
dealer for service. An indicator light
will flash while shifting. It will stay on
when the shift is completed. If for
some reason the transfer case
cannot make a requested shift, it will
return to the last chosen setting.
2
m(Two-Wheel Drive High): This
setting is used for driving in most
street and highway situations. The
front axle is not engaged in
two-wheel drive. This setting also
provides the best fuel economy.