engine GMC YUKON 2008 User Guide

Starting the Engine
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
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.
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 startand 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.
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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.
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 1-6for more information.
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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.
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.
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Active Fuel Management™
Your vehicle’s V8 engine may have Active Fuel
Management™. This system allows the engine to
operate on either all or half of its cylinders, depending
on the driving conditions.
When less power is required, such as cruising at a
constant vehicle speed, the system will operate in the
half cylinder mode, allowing your vehicle to achieve
better fuel economy. When greater power demands are
required, such as accelerating from a stop, passing,
or merging onto a freeway, the system will maintain
full-cylinder operation.
If your vehicle has an Active Fuel Management™
indicator, seeDIC Operation and Displays (With DIC
Buttons) on page 3-56orDIC Operation and Displays
(Without DIC Buttons) on page 3-61for more information
on using this display.
Automatic Transmission Operation
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
If your 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.
Hydra-Matic
®4-Speed
Automatic Transmission
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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 the engine
because your 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 Park. See Torque Lock (Automatic Transmission)
underShifting Into PARK (P) on page 2-44for more
information.
{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 2-44. If you are pulling a trailer, see
Towing a Trailer on page 4-49. Allison Transmission
®or Hydra-Matic®6-Speed
Automatic Transmission
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{CAUTION:
If you have Four-Wheel Drive, your vehicle will
be free to roll — even if your shift lever is in
PARK (P) — if your transfer case is in
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 NEUTRAL. SeeShifting Into
PARK (P) on page 2-44.
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 4-33.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.
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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.
By doing this, the vehicle shifts down to the next
gear and has more power.
DRIVE (D) can be used when towing a trailer, carrying a
heavy load, driving on steep hills, or for off-road
driving. You might 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.
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 is
able to maintain vehicle speed by analyzing things such
as vehicle speed, throttle position, and vehicle load.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 could 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 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 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 Allison
Transmission
®and Hydra-Matic®6-Speed
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.
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Four-Wheel Drive
If your vehicle has four-wheel drive, you can send your
engine’s driving power to all four wheels for extra
traction. Read the part that follows 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 your 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.
Front Axle Locking Feature
The front axle locks and unlocks automatically when
you shift the transfer case. Some delay for the axle to
lock or unlock is normal.
Automatic Transfer Case
The transfer case knob is
located to the left of the
instrument panel cluster.
Your vehicle has Four Wheel Drive with StabiliTrak
®.
For information on StabiliTrak®, seeStabiliTrak®System
on page 4-6.
Use this dial to shift into and out of four-wheel drive.
You can choose among ve driving settings:
Indicator lights in the switches show you which setting
you are in. The indicator lights will come on briey when
you turn on the ignition and the last chosen setting will
stay on. If the lights do not come on, you should take your
vehicle in for service. An indicator light will ash while
shifting. Fast ashing means the conditions were not met
to make the desired shift, typically the vehicle was going
too fast, the automatic transmission was not in neutral.
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Shifting Into Four-Wheel Drive High or
AUTO (Automatic Four-Wheel Drive)
Turn the knob to the Four-Wheel High or AUTO position.
This can be done at any speed, except when shifting
from Four-Wheel Drive Low. The indicator light will ash
while shifting. It will remain on when the shift is
completed.
Shifting Into Two-Wheel Drive High
Turn the knob to the Two-Wheel 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 later in this
section for more information.
Shifting Into Four-Wheel Drive Low
When Four-Wheel Low is engaged, vehicle speed
should be kept below 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 3 mph (5 km/h) with
the transmission in NEUTRAL (N). The preferred method
for shifting into Four-Wheel Drive Low is to have your
vehicle moving 1 to 2 mph (1.6 to 3.2 km/h).Turn the knob to the Four-Wheel Drive Low position.
You must wait for the Four-Wheel Drive Low indicator
light to stop ashing and remain on before shifting
your transmission in gear.
Notice:Shifting the transmission into gear before
the Four-Wheel Drive Low indicator light has
stopped ashing could damage the transfer case.
To help avoid damaging your vehicle, always
wait for the Four-Wheel Drive Low indicator light to
stop ashing before shifting the transmission
into gear.
The vehicle may have signicant engagement noise and
bump when shifting between Four-Wheel Drive Low
and Four-Wheel Drive High ranges or from NEUTRAL
while the engine is running.
If the knob is turned to the Four-Wheel Drive Low position
when your vehicle is in gear and/or moving, the
Four-Wheel Drive Low indicator light will ash for
30 seconds and not complete the shift unless your
vehicle is moving less than 3 mph (5 km/h) and the
transmission is in NEUTRAL (N). After 30 seconds the
transfer case will shift to Four-Wheel Drive High mode.
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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, your vehicle
must be stopped or moving less than 3 mph (5 km/h)
with the transmission in NEUTRAL (N) and the ignition in
ON/RUN. The preferred method for shifting out of
Four-Wheel Drive Low is to have your vehicle moving
1 to 2 mph (1.6 to 3.2 km/h). 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 ashing and remain on before shifting your
transmission into gear.
Notice:Shifting the transmission into gear before
the Four-Wheel Drive Low indicator light has
stopped ashing could damage the transfer case.
To help avoid damaging your vehicle, always
wait for the Four-Wheel Drive Low indicator light to
stop ashing before shifting the transmission
into gear.
The vehicle may have signicant engagement noise and
bump when shifting between Four-Wheel Drive Low
and Four-Wheel Drive High ranges or from 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
your vehicle is in gear and/or moving, the Four-Wheel
Drive High, AUTO or Two-Wheel Drive High indicator
light will ash for 30 seconds but will not complete
the shift unless your vehicle is moving less than 3 mph
(5 km/h) and the transmission is in NEUTRAL (N).
Shifting into NEUTRAL
To shift the transfer case to 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. SeeParking Brake on page 2-43for more
information.
3. Start the vehicle or turn the ignition to ON/RUN.
4. Put the transmission in NEUTRAL (N).
5. Shift the transfer case to Two-Wheel Drive High.
6. Turn the transfer case dial clockwise to NEUTRAL
till it stops and hold it for 10 seconds. Then slowly
release the dial to the four low position. The
NEUTRAL light will come on when the transfer case
shift to NEUTRAL is complete.
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