2007 GMC YUKON brakes

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

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

Torque Lock
If you are parking on a hill and you do not shift
your transmission into PARK (P) properly,
the weight of the vehicle may put too much force
on the parking pawl in the transmission. You
may nd it difficult to pull the shift lever out
of PARK (P). This is called torque lock. To prevent
torque lock, set the parking brake and then shift
into PARK (P) properly before you leave the
driver’s seat. To nd out how, seeShifting Into
Park (P) on page 153.
When you are ready to drive, move the shift lever
out of PARK (P) before you release the parking
brake.
If torque lock does occur, you may need to have
another vehicle push yours a little uphill to
take some of the pressure from the parking pawl
in the transmission, then you will be able to
pull the shift lever out of PARK (P).
Shifting Out of Park (P)
Your vehicle has an automatic transmission shift
lock control system which locks the shift lever
in PARK (P) when the ignition is in the LOCK.
You have to fully apply your regular brakes before
you can shift from PARK (P) when the ignition
is in RUN. SeeAutomatic Transmission Operation
on page 145.
If you cannot shift out of PARK (P), ease pressure
on the shift lever and push the shift lever all the
way up into PARK (P) as you maintain brake
application. Then, move the shift lever into
the desired gear.
154

Cruise Control
{CAUTION:
Cruise control can be dangerous where
you cannot drive safely at a steady speed.
So, do not use your cruise control on
winding roads or in heavy traffic.
Cruise control can be dangerous on
slippery roads. On such roads, fast
changes in tire traction can cause
excessive wheel slip, and you could lose
control. Do not use cruise control on
slippery roads.
With cruise control, you can maintain a speed
of about 25 mph (40 km/h) or more without
keeping your foot on the accelerator. This can
really help on long trips. Cruise control does not
work at speeds below about 25 mph (40 km/h).When you apply your brakes, cruise control is
turned off.
If your vehicle has the StabiliTrak
®system and
begins to limit wheel spin while you are using
cruise control, the cruise control will automatically
disengage. SeeStabiliTrak
®System on
page 349. When road conditions allow you to
safely use it again, you may turn the cruise
control back on.
The cruise control
buttons are located
on left side of the
steering wheel.
200

A trailer was attached to your vehicle, or a
bicycle or an object was hanging out of your
trunk during your last drive when you turned off
the vehicle. If the attached objects are removed
from your vehicle before the start of your next
drive, the system will return to normal operation
unless an object is detected when the vehicle is
shifted into REVERSE (R). If this occurs, URPA
assumes the object is still attached, so you will
have to wait until the vehicle is driven forward
above 15 mph (25 km/h) before URPA will
return to normal operation.
The ultrasonic sensors are not kept clean. So,
be sure to keep your vehicle’s rear bumper free
of mud, dirt, snow, ice, and slush. For cleaning
instructions, seeWashing Your Vehicle on
page 530. If the DIC still displays the PARKING
ASSIST OFF message after cleaning the
bumper and driving forward at a speed of at
least 15 mph (25 km/h), see your dealer.
Other conditions that may affect system
performance include vibrations from a
jackhammer or the compression of air brakes
on a very large truck or other mechanical
devices that interfere with URPA performance.
When URPA is disabled without driver action
and the driver attempts to turn URPA back on
using the Driver Information Center (DIC), the
PARKING ASSIST ON option will not be
selectable if the necessary conditions stated
above for normal system operation are not met.
As always, drivers should use care when backing
up a vehicle. Always look behind you, being
sure to check for other vehicles, obstructions and
blind spots.
For Driver Information Center messages related
to URPA, seeDIC Warnings and Messages
on page 252.
If the bumper is damaged, your URPA system
may not work properly. Take the vehicle to
your dealer to repair the system.
212

Readings in the low warning zone may occur
when a large number of electrical accessories are
operating in the vehicle and the engine is left at
an idle for an extended period. This condition
is normal since the charging system is not able to
provide full power at engine idle. As engine
speeds are increased, this condition should correct
itself as higher engine speeds allow the charging
system to create maximum power.
You can only drive for a short time with the
reading in either warning zone. If you must drive,
turn off all unnecessary accessories.
Readings in either warning zone indicate a
possible problem in the electrical system. Have
the vehicle serviced as soon as possible.Brake System Warning Light
With the ignition on, the brake system warning
light will come on when you set the parking brake.
If you try to drive with the parking brake engaged,
a chime will sound when the vehicle speed is
greater than 3 mph (5 km/h).
Your vehicle’s hydraulic brake system is divided
into two parts. If one part is not working, the other
part can still work and stop you. For good
braking, though, you need both parts working well.
If the warning light comes on and a chime
sounds there could be a brake problem. Have
your brake system inspected right away.
This light may also come on due to low brake
uid. SeeBrakes on page 459for more
information.
233

That’s normal. If the light does not come on then,
have it xed so it will be ready to warn you if
there is a problem.
If the light stays on, or comes on when you are
driving, your vehicle needs service. You will
also hear a chime sound when the light is on
steady. If the regular brake system warning light is
not on, you still have brakes, but you do not
have anti-lock brakes. If the regular brake system
warning light is also on you do not have anti-lock
brakes and there is a problem with your regular
brakes. In addition to both lights, you will also hear
a chime sound on the rst occurrence of a
problem and each time the vehicle is shut off and
then restarted. SeeBrake System Warning
Light on page 233.
The anti-lock brake system warning light should
come on briey when you turn the ignition
key to RUN. If the light does not come on then,
have it xed so it will be ready to warn you if there
is a problem.StabiliTrak®Indicator Light
For vehicles equipped
with the StabiliTrak®
system, this warning
light should come
on briey when the
engine is started.
If the warning light does not come on then, have it
xed so it will be ready to warn you if there is a
problem. If it stays on, or comes on when you are
driving, there may be a problem with your
StabiliTrak
®system and your vehicle may need
service. When this warning light is on, the system
will not limit wheel spin. Adjust your driving
accordingly.
If the StabiliTrak
®system warning light comes on
and stays on for an extended period of time
when the system is turned on, your vehicle needs
service. SeeStabiliTrak
®System on page 349
for more information.
235

SERVICE BRAKES SOON
If there is a problem with the brake system, this
message will display. If this message appears,
stop as soon as possible and turn off the vehicle.
Restart the vehicle and check for the message
on the DIC display. If the message is still displayed
or appears again when you begin driving, the
brake system needs service. See your dealer.
SERVICE PARK ASSIST
This message will display if there is a problem
with the Ultrasonic Rear Parking Assist (URPA)
system. Do not use this system to help you park.
SeeUltrasonic Rear Parking Assist (URPA) on
page 208for more information. See your dealer for
service.
SERVICE STABILITRAK
If your vehicle has StabiliTrak®and this message
displays, it means there may be a problem
with the StabiliTrak
®system. If you see this
message, try to reset the system. Stop; turn off
the engine for at least 15 seconds; then start
the engine again. If this message still comes on, it
means there is a problem. You should see your
dealer for service. The vehicle is safe to drive,
however, you do not have the benet of
StabiliTrak
®, so reduce your speed and drive
accordingly.
SERVICE SUSPENSION SYSTEM
If your vehicle has the Autoride®suspension
system, this message will display when the
Autoride
®suspension system is not operating
properly. Have your vehicle serviced by your
dealer.
258