2008 GMC YUKON DENALI automatic transmission

Automatic Release Fold and Tumble
Feature
The transmission must be in PARK (P) for this feature
to work.
Folding and Tumbling the Seat(s)
{CAUTION:
Automatically folding and tumbling the seat
when someone is sitting in the seat, could
cause injury to the person sitting there. Always
make sure there is no one sitting in the seat
before pressing the automatic seat release
button.
To fold and tumble the seat, do the following:
1. Make sure that there is nothing under, in front of, or
on the seat.
Notice:Folding a rear seat with the safety belts
still fastened may cause damage to the seat or the
safety belts. Always unbuckle the safety belts
and return them to their normal stowed position
before folding a rear seat.2. From the front seats,
press one of the
automatic seat release
buttons located on
the overhead console.
When accessing the third row seats, if your vehicle
has them, from the outside of the vehicle, press
the button on the panel behind either rear door.
One press of the button automatically folds
the seatback at and tumbles the seat forward.
There will be a slight delay between the folding of
the seatback and the tumbling of the seat. Overhead Console
Buttons shown, Panel
Button similar
1-13

2. Lift the lever, located
on the bottom rear of
the second row seat on
the inboard side, to
release the seatback.
The seatback will
fold forward.
3. Lift the lever again to release the rear of the seat
from the oor. The seat will tumble forward.Automatic Release Fold and Tumble
Feature
The transmission must be in PARK (P) for this feature
to work.
Folding and Tumbling the Seat(s)
{CAUTION:
Automatically folding and tumbling the seat
when someone is sitting in the seat, could
cause injury to the person sitting there. Always
make sure there is no one sitting in the seat
before pressing the automatic seat release
button.
To fold and tumble the seat, do the following:
1. Make sure that there is nothing under, in front of, or
on the seat.
Notice:Folding a rear seat with the safety belts
still fastened may cause damage to the seat or the
safety belts. Always unbuckle the safety belts
and return them to their normal stowed position
before folding a rear seat.
1-20

Keys...............................................................2-3
Remote Keyless Entry (RKE) System................2-4
Remote Keyless Entry (RKE) System
Operation...................................................2-5
Remote Vehicle Start......................................2-8
Doors and Locks............................................2-10
Door Locks..................................................2-10
Power Door Locks........................................2-11
Delayed Locking...........................................2-11
Programmable Automatic
Door Locks...............................................2-11
Rear Door Security Locks..............................2-12
Lockout Protection........................................2-12
Liftgate/Liftglass............................................2-13
Power Liftgate..............................................2-15
Power Running Boards..................................2-18
Windows........................................................2-19
Power Windows............................................2-20
Sun Visors...................................................2-21
Theft-Deterrent Systems..................................2-21
Content Theft-Deterrent.................................2-22
PASS-Key
®III+............................................2-23
PASS-Key®III+ Operation..............................2-24Starting and Operating Your Vehicle................2-25
New Vehicle Break-In....................................2-25
Ignition Positions..........................................2-26
Retained Accessory Power (RAP)...................2-27
Starting the Engine.......................................2-27
Adjustable Throttle and Brake Pedal................2-29
Engine Coolant Heater..................................2-29
Automatic Transmission Operation...................2-30
Tow/Haul Mode............................................2-34
Parking Brake..............................................2-35
Shifting Into PARK (P)...................................2-36
Shifting Out of PARK (P)...............................2-37
Parking Over Things That Burn.......................2-38
Engine Exhaust............................................2-38
Running the Engine While Parked...................2-39
Mirrors...........................................................2-40
Automatic Dimming Rearview Mirror with
OnStar
®, Compass and Temperature
Display....................................................2-40
Outside Power Foldaway Mirrors.....................2-42
Object Detection Systems...............................2-44
Ultrasonic Rear Parking Assist (URPA)............2-44
Section 2 Features and Controls
2-1

The power liftgate may be temporarily disabled under
extreme temperatures, or under low battery conditions.
If this occurs, the liftgate can still be operated
manually.
If you shift the transmission out of PARK (P) while the
power function is in progress, the liftgate power function
will continue to completion. If you shift the transmission
out of PARK (P) and accelerate before the power
liftgate latches closed, the liftgate may reverse to the
open position. Cargo could fall out of the vehicle. Always
make sure the power liftgate is closed and latched
before you drive away.
If you power open the liftgate and the liftgate support
struts have lost pressure, the lights will ash and a
chime will sound. The liftgate will stay open temporarily,
then slowly close. See your dealer/retailer for service
before using the liftgate.Obstacle Detection Features
If the liftgate encounters an obstacle during a power
open or close cycle, a warning chime will sound and the
liftgate will automatically reverse direction to the full
closed or open position. After removing the obstruction,
the power liftgate operation can be used again. If the
liftgate encounters multiple obstacles on the same power
cycle, the power function will deactivate, and you
must manually open or close the liftgate. The REAR
ACCESS OPEN warning message in the Driver
Information Center (DIC) will indicate that the liftgate is
open. After removing the obstructions, manually
open the liftgate to the full open position or close the
liftgate to the fully closed and latched position. The
liftgate will now resume normal power operation.
Your vehicle has pinch sensors located on the side
edges of the liftgate. If an object is caught between the
liftgate and the body and presses against this sensor,
the liftgate will reverse direction and open fully.
The liftgate will remain open until it is activated again or
closed manually. Do not force the liftgate open or
closed during a power cycle.
2-17

3. Plug the cord into a normal, grounded 110-volt
AC outlet.
{CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the
wrong kind of extension cord could overheat
and cause a re. You could be seriously
injured. Plug the cord into a properly grounded
three-prong 110-volt AC outlet. If the cord will
not reach, use a heavy-duty three-prong
extension cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug and
store the cord as it was before to keep it away
from moving engine parts. If you do not, it could be
damaged.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead
of trying to list everything here, we ask that you contact
your dealer/retailer in the area where you will be
parking your vehicle. The dealer/retailer can give you
the best advice for that particular area.
Automatic Transmission Operation
Your vehicle has a Hydra-Matic®6L80 automatic
transmission, and has an electronic shift position
indicator within the instrument panel cluster. The
electronic shift position indicator displays when the shift
lever is moved out of PARK (P).
There are several different positions for the shift lever.
See “Range Selection Mode” later in this section.
PARK (P):This position locks your rear wheels. It is
the best position to use when you start your engine
because your vehicle cannot move easily.
When parked on a hill, especially when the vehicle has
a heavy load, you may notice an increase in the
effort to shift out of Park. See Torque Lock (Automatic
Transmission) underShifting Into PARK (P) on
page 2-36for more information.
2-30

DRIVE (D):This position is for normal driving. It
provides the best fuel economy for your vehicle. If you
need more power for passing, and you are:
Going less than about 35 mph (55 km/h), push your
accelerator pedal about halfway down.
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
DRIVE (D) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road
driving. You may want to shift the transmission to a
lower gear selection if the transmission shifts too often.
Downshifting the transmission in slippery road
conditions could result in skidding, see “Skidding” under
Loss of Control on page 4-12
When temperatures are very cold, the Hydra-Matic
®
Automatic Transmission’s gear shifting may be delayed
providing more stable shifts until the engine warms
up. Shifts may be more noticeable with a cold
transmission. This difference in shifting is normal.
MANUAL MODE (M):This position lets drivers select
the range of gears appropriate for current driving
conditions. See Range Selection Mode later in
this section.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 your warranty. If you are stuck,
do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.
Your vehicle has a shift stabilization feature that adjusts
the transmission shifting to the current driving conditions
in order to reduce rapid upshifts and downshifts. This shift
stabilization feature is designed to determine, before
making an upshift, if the engine will be able to maintain
vehicle speed by analyzing things such as throttle
position, vehicle load, and hill grade. If the shift
stabilization feature determines that a current vehicle
speed cannot be maintained, the transmission does not
upshift and instead holds the current gear. In some
cases, this may appear to be a delayed shift, however the
transmission is operating normally.
Your vehicle’s transmission uses adaptive shift controls.
Adaptive shift controls continually compares key shift
parameters to pre programmed ideal shift conditions
stored in the transmissions computer. The transmission
constantly makes adjustments to improve vehicle
performance according to the way the vehicle is being
used, such as with a heavy load. During this adaptive
shift controls process, some shifts may feel different as
the transmission determines the best settings for a
particular shift.
2-32

Range Selection Mode
On vehicles with a Range Selection Mode. The Range
Selection Mode controls the vehicle’s transmission.
To use this feature, do the following:
1. Move the shift lever to the MANUAL MODE (M).
2. Press the plus/minus button, to upshift or downshift
selecting the desired range of gears for your current
driving conditions.When in the MANUAL MODE (M) a number displays next
to the M, indicating the current gear that has been
selected. The number displayed in the gear indicator is
the highest gear that can be used. However, your vehicle
can automatically shift to lower gears as it adjusts to
driving conditions. This means that all gears below that
number are available. When FIFTH (5) is selected,
FIRST (1) through FIFTH (5) gears are automatically
shifted by the vehicle, but SIXTH (6) cannot be used until
the plus/minus button located on the steering column
lever is used to change to the gear.
The Range Selection Mode controls the vehicle and
engine speed while driving down a hill or towing a trailer,
by allowing you to select a desired range of gears.
Grade Braking is not available when the Range
Selection Mode is active. SeeTow/Haul Mode on
page 2-34for more information.
While using the Range Selection Mode, Cruise Control
and the Tow/Haul mode can be used.
2-33

Tow/Haul Mode
Your vehicle has a tow/haul mode. The tow/haul mode
adjusts the transmission shift pattern to reduce shift
cycling, providing increased performance, vehicle
control, and transmission cooling when towing or hauling
heavy loads.Press the button located on the end of the shift lever to
turn the tow/haul on or off. When the tow/haul is on,
a light on the instrument panel cluster will come on.
SeeTow/Haul Mode Light on page 3-47for more
information.
Also see “Tow Haul Mode” underTowing a Trailer on
page 4-42for more information.
The tow/haul mode works with the Autoride
®feature, if
the vehicle has this, to enhance the ride when trailering or
with a loaded vehicle. SeeAutoride
®on page 4-41.
Grade Braking
Grade Braking assists when driving on a downhill grade.
It maintains the vehicle’s speed by automatically
implementing a shift schedule that uses the engine and
the transmission to slow the vehicle. This reduces
wear on the brakes system and increases control of the
vehicle. The system constantly monitors the vehicle’s
speed, acceleration, throttle position, and whether
the brake pedal is being pressed, and determines when
to keep the current vehicle speed or to slow down.
The system will then automatically command downshifts
that reduces the vehicles speed, until the brake pedal
is no longer being pressed. This indicates the desired
vehicle speed has been reached.
2-34