engine GMC YUKON DENALI 2008 User Guide

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

Adjustable Throttle and Brake Pedal
On vehicles with this feature, you can change the
position of the throttle and brake pedals.
This feature is designed for shorter drivers, since the
pedals cannot move farther away from the standard
position, but can move toward the driver for better pedal
reach.
No adjustment to the pedals can be made when the
vehicle is in REVERSE (R) or while using the cruise
control.
The switch used to adjust
the pedals is located on
the instrument panel below
the climate control
system.Press the arrow at the bottom of the switch to move the
pedals closer to your body. Press the arrow at the top of
the switch to move the pedals away from your body.
Before you start driving, fully press the brake pedal to
conrm the adjustment is right for you. While driving,
make only small adjustments.
Your vehicle may have a memory function which lets
pedal settings be saved and recalled. SeeMemory Seat,
Mirrors, and Pedals on page 1-4for more information.
Engine Coolant Heater
The engine coolant heater, if available, can help in cold
weather conditions at or below 0°F (−18°C) for easier
starting and better fuel economy during engine warm-up.
Plug in the coolant heater at least four hours before
starting your vehicle. An internal thermostat in the
plug-end of the cord may exist which will prevent
engine coolant heater operation at temperatures
above 0°F (−18°C).
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord.
The cord is located on the driver’s side of the
engine compartment, near the power steering
uid reservoir.
2-29

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

{CAUTION:
It is dangerous to get out of your vehicle if the
shift lever is not fully in PARK (P) with the
parking brake rmly set. Your vehicle can roll.
Do not leave your 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 your vehicle will not move, even when
you are on fairly level ground, always set your
parking brake and move the shift lever to
PARK (P). SeeShifting Into PARK (P) on
page 2-36. If you are pulling a trailer, see
Towing a Trailer on page 4-42.
REVERSE (R):Use this gear to back up.
Notice:Shifting to REVERSE (R) while your vehicle
is moving forward could damage the transmission.
The repairs would not be covered by your warranty.
Shift to REVERSE (R) only after your vehicle is
stopped.To rock your vehicle back and forth to get out of snow,
ice, or sand without damaging your transmission, seeIf
Your Vehicle is Stuck in Sand, Mud, Ice, or Snow on
page 4-32.
NEUTRAL (N):In this position, your engine does not
connect with the wheels. To restart when you are
already moving, use NEUTRAL (N) only. Also, use
NEUTRAL (N) when your vehicle is being towed.
{CAUTION:
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless
your foot is rmly on the brake pedal, your
vehicle could move very rapidly. You could
lose control and hit people or objects. Do not
shift into a drive gear while your engine is
running at high speed.
Notice:Shifting out of PARK (P) or NEUTRAL (N)
with the engine running at high speed may damage
the transmission. The repairs would not be
covered by your warranty. Be sure the engine is not
running at high speed when shifting your vehicle.
2-31

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

Shifting Into PARK (P)
{CAUTION:
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake rmly set. Your vehicle can
roll. If you have left the engine running, the
vehicle can move suddenly. You or others
could be injured. To be sure your vehicle will
not move, even when you are on fairly level
ground, use the steps that follow. If you are
pulling a trailer, seeTowing a Trailer on
page 4-42.
1. Hold the brake pedal down with your right foot and
set the parking brake.
2. Move the shift lever into the PARK (P) position by
pulling the shift lever toward you and moving it up
as far as it will go.
3. Turn the ignition key to LOCK/OFF.
4. Remove the key and take it with you. If you can
leave your vehicle with the ignition key in your
hand, your vehicle is in PARK (P).
Leaving Your Vehicle With the Engine
Running
{CAUTION:
It can be dangerous to leave your vehicle with
the engine running. Your vehicle could move
suddenly if the shift lever is not fully in
PARK (P) with the parking brake rmly set.
And, if you leave the vehicle with the engine
running, it could overheat and even catch re.
You or others could be injured. Do not leave
your vehicle with the engine running.
If you have to leave your vehicle with the engine
running, be sure your vehicle is in PARK (P) and the
parking brake is rmly set. After the shift lever is moved
into PARK (P), hold the regular brake pedal down.
Then, see if you can move the shift lever away from
PARK (P) without rst pulling it toward you. If you can, it
means that the shift lever was not fully locked into
PARK (P).
2-36

Parking Over Things That Burn
{CAUTION:
Things that can burn could touch hot exhaust
parts under your vehicle and ignite. Do not
park over papers, leaves, dry grass, or other
things that can burn.
Engine Exhaust
{CAUTION:
Engine exhaust can kill. It contains the gas
carbon monoxide (CO), which you cannot see or
smell. It can cause unconsciousness and death.
You might have exhaust coming in if:
The exhaust system sounds strange or
different.
Your vehicle gets rusty underneath.
Your vehicle was damaged in a collision.
Your vehicle was damaged when driving
over high points on the road or over road
debris.
Repairs were not done correctly.
Your vehicle or the exhaust system has
been modied improperly.
If you ever suspect exhaust is coming into your
vehicle:
Drive it only with all the windows down to
blow out any CO; and
Have your vehicle xed immediately.
2-38

Running the Engine While Parked
It is better not to park with the engine running. But if you
ever have to, here are some things to know.
{CAUTION:
Idling the engine with the climate control
system off could allow dangerous exhaust into
your vehicle. See the earlier caution under
Engine Exhaust on page 2-38.
Also, idling in a closed-in place can let deadly
carbon monoxide (CO) into your vehicle even if
the climate control fan is at the highest setting.
One place this can happen is a garage.
Exhaust — with CO — can come in easily.
NEVER park in a garage with the engine
running.
Another closed-in place can be a blizzard. See
Winter Driving on page 4-29.
{CAUTION:
It can be dangerous to get out of your vehicle
if the shift lever is not fully in PARK (P) with
the parking brake rmly set. Your vehicle can
roll. Do not leave your 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 your vehicle will not move, even when
you are on fairly level ground, always set the
parking brake and move the shift lever to
PARK (P).
Follow the proper steps to be sure your vehicle will not
move. SeeShifting Into PARK (P) on page 2-36.
If you are pulling a trailer, seeTowing a Trailer on
page 4-42.
2-39