2007 GMC YUKON Owner's Manual

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 in the area where you will be parking your
vehicle. The dealer can give you the best
advice for that particular area.Automatic Transmission Operation
Your vehicle has an 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 “Driver Shift Control (DSC)” later in this
section.
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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) under
Shifting Into Park (P) on page 153for 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). See
Shifting Into Park (P) on page 153.Ifyou
are pulling a trailer, seeTowing a Trailer
on page 400.
146

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 390.
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 your
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.
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
underLoss of Control on page 357.
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. If your vehicle has this feature,
see “Driver Shift Control” 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. 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.
148

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.Driver Shift Control (DSC)
Your vehicle has a Driver Shift Control (DSC).
The DSC 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.
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When in the MANUAL MODE (M) a number will
display 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 DSC 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.
The transmission will prevent a gear range until a
speed that is appropriate for current driving
conditions is achieved. If shifting is prevented for
any reason, the currently selected gear will
ash multiple times in the instrument panel cluster.
Grade Braking is not available when the Driver
Shift Control is active. SeeTow/Haul Mode
on page 150for more information.
While using the DSC, Cruise Control and the
Tow/Haul mode can be used.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.
150

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 242for more
information.
Also see “Tow Haul Mode” underTowing a Trailer
on page 400for 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. See
Autoride
®on page 399.
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.
The tow/haul mode and grade braking shift
modes can be activated by pressing the button on
the end of the shift control stalk. While in the
DSC mode, grade braking is deactivated, allowing
the driver to select a gear.
SeeAutomatic Transmission Operation on
page 145for more information.
151

Parking Brake
To set the parking brake, hold the regular brake
pedal down with your right foot. Push down
the parking brake pedal with your left foot.
A chime will activate and the warning light will
ash when the parking brake is applied and
the vehicle is moving at least 3 mph (5 km/h) for
at least three seconds.
To release the parking brake, hold the regular
brake pedal down.Pull the bottom edge of the lever, located above
the parking brake pedal, with the parking
brake symbol, to release the parking brake.
If the ignition is on when the parking brake is
released, the brake system warning light will go off.
Notice:Driving with the parking brake on
can overheat the brake system and cause
premature wear or damage to brake system
parts. Verify that the parking brake is fully
released and the brake warning light is
off before driving.
If you are towing a trailer and are parking on any
hill, seeTowing a Trailer on page 400.
152