2008 GMC YUKON DENALI 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

Ignition Positions
Use the key to turn the
ignition switch to four
different positions.
In order to shift out of PARK (P), ignition must be in the
ON/RUN or ACC/ACCESSORY and the regular brake
pedal must be applied.A (LOCK/OFF):This position locks the ignition and
transmission. It is a theft-deterrent feature. The key can
only be removed when the ignition is turned to
LOCK/OFF.
Notice:Using a tool to force the key from the
ignition switch could cause damage or break the
key. Use the correct key and turn the key only with
your hand. Make sure the key is all the way in. If
it is, turn the steering wheel left and right while you
turn the key hard. If none of this works, then
your vehicle needs service.
B (ACC/ACCESSORY):This position lets things like
the radio and the windshield wipers operate while
the engine is off.
Lengthy operation of features such as the radio in the
ACC/ACCESSORY ignition position and the ON/RUN
position may drain the battery and prevent your vehicle
from starting. Do not operate your vehicle in the
ACC/ACCESSORY ignition position for a long period
of time.
2-26

C (ON/RUN):This is the position for driving. It is the
position the ignition switch returns to after the engine
starts, and the key is released.
The battery could be drained if you leave the key in the
ACC/ACCESSORY or ON/RUN position with the engine
off. You may not be able to start your vehicle if the battery
is allowed to drain for an extended period of time.
D (START):This position starts the engine.
Key In the Ignition
Never leave your vehicle with the keys inside, as it is an
easy target for joy riders or thieves. If you leave the
key in the ignition and park your vehicle, a chime
will sound, when you open the driver’s door. Always
remember to remove your key from the ignition and take
it with you. This will lock your ignition and transmission.
Also, always remember to lock the doors.
The battery could be drained if you leave the key in the
ignition while your vehicle is parked. You may not be
able to start your vehicle after it has been parked for an
extended period of time.
Retained Accessory Power (RAP)
The following vehicle accessories can be used for up to
10 minutes after the engine is turned off:
Audio System
Power Windows
OnStar®System (if equipped)
Sunroof (if equipped)
These features work when the key is in ON/RUN or
ACC/ACCESSORY. Once the key is turned from
ON/RUN to LOCK/OFF, the windows and sunroof
continue to work up to 10 minutes until any door
is opened. The radio continues to work for up to
10 minutes or until the driver’s door is opened.
Starting the Engine
Move your shift lever to PARK (P) or NEUTRAL (N).
Your engine will not start in any other position – this is a
safety feature. To restart when you are already
moving, use NEUTRAL (N) only.
Notice:Do not try to shift to PARK (P) if your
vehicle is moving. If you do, you could damage the
transmission. Shift to PARK (P) only when your
vehicle is stopped.
2-27

Starting Procedure
1. With your foot off the accelerator pedal, turn the
ignition key to START. When the engine starts,
let go of the key. The idle speed will go down as
your engine gets warm. Do not race the engine
immediately after starting it. Operate the engine and
transmission gently to allow the oil to warm up
and lubricate all moving parts.
Your vehicle has a Computer-Controlled Cranking
System. This feature assists in starting the
engine and protects components. If the ignition key
is turned to the START position, and then
released when the engine begins cranking, the
engine will continue cranking for a few seconds or
until the vehicle starts. If the engine does not
start and the key is held in START for many
seconds, cranking will be stopped after 15 seconds
to prevent cranking motor damage. To prevent
gear damage, this system also prevents cranking if
the engine is already running. Engine cranking
can be stopped by turning the ignition switch to the
ACC/ACCESSORY or LOCK/OFF position.
Notice:Cranking the engine for long periods of
time, by returning the key to the START position
immediately after cranking has ended, can overheat
and damage the cranking motor, and drain the
battery. Wait at least 15 seconds between each try,
to let the cranking motor cool down.2. If the engine does not start after 5-10 seconds,
especially in very cold weather (below 0°F or−18°C),
it could be ooded with too much gasoline. Try
pushing the accelerator pedal all the way to the oor
and holding it there as you hold the key in START for
up to a maximum of 15 seconds. Wait at least
15 seconds between each try, to allow the cranking
motor to cool down. When the engine starts, let go of
the key and accelerator. If the vehicle starts briey
but then stops again, do the same thing. This clears
the extra gasoline from the engine. Do not race the
engine immediately after starting it. Operate the
engine and transmission gently until the oil warms up
and lubricates all moving parts.
Notice:The engine is designed to work with the
electronics in your vehicle. If you add electrical
parts or accessories, you could change the way the
engine operates. Before adding electrical equipment,
check with your dealer/retailer. If you do not, your
engine might not perform properly. Any resulting
damage would not be covered by your vehicle’s
warranty.
2-28

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