2009 GMC YUKON brakes

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.
The 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 the 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 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.M (Manual Mode):This position is available on
vehicles with the Hydra-Matic
®6-Speed transmission.
It lets drivers select the range of gears appropriate
for current driving conditions. If the vehicle has
this feature, see Range Select Mode (Hydra-Matic
®
6-Speed transmission) later in this section.
3 (Third):This position is also used for normal driving.
It reduces vehicle speed more than D (Drive) without
using the brakes. You might choose 3 (Third) instead of
D (Drive) when driving on hilly, winding roads, when
towing a trailer, so there is less shifting between gears
and when going down a steep hill.
2 (Second):This position reduces vehicle speed even
more than 3 (Third) without using the brakes. You can
use 2 (Second) on hills. It can help control vehicle speed
as you go down steep mountain roads, but then you
would also want to use the brakes off and on.
If you manually select 2 (Second) in an automatic
transmission, the transmission will start in second gear.
You can use this feature for reducing the speed of the
rear wheels when you are trying to start the vehicle from
a stop on slippery road surfaces.
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1 (First):For the Hydra-Matic®4-Speed transmission
this position reduces vehicle speed even more than
2 (Second) without using the brakes. You can use it on
very steep hills, or in deep snow or mud. If the shift
lever is put in 1 (First) while the vehicle is moving
forward, the transmission does not shift into rst gear
until the vehicle is going slowly enough.
For a Hydra-Matic
®6-Speed transmission, this position
reduces vehicle speed without using the brakes. You can
use it for major/severe downgrades and off-road driving
where the vehicle would otherwise accelerate due to
steepness of grade. When you shift to 1 (First) it provides
the lowest gear appropriate to the vehicle’s current road
speed and continues to downshift as the vehicle slows,
eventually downshifting to 1 (First) gear.
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 the vehicle warranty. If you are stuck, do
not spin the tires. When stopping on a hill, use the
brakes to hold the vehicle in place.
Range Selection Mode (Hydra-Matic®
6-Speed Transmission)
The vehicle may have a Range Selection Mode. The
Range Selection Mode helps control the vehicle’s
transmission and vehicle speed while driving down hill
or towing a trailer by letting you select a desired range
of gears.
To use this feature, do the following:
1. Move the shift lever to M (Manual Mode).
2. Press the plus/minus buttons, located on the
steering column shift lever, to select the desired
range of gears for the current driving conditions.Base trim shown (uplevel similar)
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When M (Manual Mode) is selected a number displays
next to the M, indicating the current gear.
This number is the highest gear that can be used.
However, the vehicle can automatically shift to lower
gears as it adjusts to driving conditions. This means
that all gears below that number are available. When
5 (Fifth) is selected, 1 (First) through 5 (Fifth) gears
are automatically shifted by the vehicle, but 6 (Sixth)
cannot be used until the plus/minus button located
on the steering column lever is used to change to
the gear.
Grade Braking is not available when Range Selection
Mode is active. SeeTow/Haul Mode on page 2-35
While using Range Selection Mode, cruise control and
the Tow/Haul mode can be used.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 the vehicle warranty. If you
are stuck, do not spin the tires. When stopping on a
hill, use the brakes to hold the vehicle in place.
Low Traction Mode
If the vehicle has the Hydra-Matic®6-Speed Automatic
Transmission, it has a Low Traction Mode that assists
in vehicle acceleration when road conditions are
slippery, such as with ice or snow. While the vehicle is
at a stop, select the second gear range using Range
Selection Mode. This will limit torque to the wheels after
it detects wheel slip, preventing the tires from spinning.
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The indicator light will come on and PARK ASSIST OFF
displays on the Driver Information Center (DIC) to
indicate that URPA is off, seeDIC Warnings and
Messages on page 3-64for information about clearing
the message.
When the System Does Not Seem to
Work Properly
If the URPA system will not activate due to a temporary
condition, the message PARK ASSIST OFF will be
displayed on the DIC and a red light will be shown on
the rear URPA display when the shift lever is moved into
R (Reverse). This occurs under the following conditions:
The driver disables the system.
The ultrasonic sensors are not clean. Keep the
vehicle’s rear bumper free of mud, dirt, snow,
ice and slush. For cleaning instructions, see
Washing Your Vehicle on page 5-111.
A trailer was attached to the vehicle, or a bicycle or
an object was hanging out of the liftgate during the
last drive cycle, the red light may illuminate in
the rear display. Once the attached object is
removed, URPA will return to normal operation.
A tow bar is attached to the vehicle.
The vehicle’s bumper is damaged. Take the vehicle
to your dealer/retailer to repair the system.
Other conditions may affect system performance,
such as vibrations from a jackhammer or the
compression of air brakes on a very large truck.
If the system is still disabled, after driving forward at
least 15 mph (25 km/h), take the vehicle to your
dealer/retailer.
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Cruise Control
{CAUTION:
Cruise control can be dangerous where you
cannot drive safely at a steady speed. So, do not
use the 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, a speed of about 25 mph (40 km/h)
or more can be maintained without keeping your foot
on the accelerator. Cruise control does not work
at speeds below about 25 mph (40 km/h).
When the brakes are applied, cruise control is
turned off.
If the vehicle has StabiliTrak
®, and the system begins to
limit wheel spin, cruise control will automatically
disengage. SeeStabiliTrak
®System on page 4-6. When
road conditions allow the cruise control to be safely
used again, it can be turned back on.The cruise control buttons are located on left side of the
steering wheel.
T(On/Off):This button can both activate and turn off
the system. The indicator light on the button turns on
when cruise control is on and turns off when cruise
control is off.
+ RES (Resume/Accelerate):Press to make the
vehicle accelerate or resume to a previously set speed.
SET−(Set/Coast):Press to set the speed or make
the vehicle decelerate.
[(Cancel):Press to cancel cruise control without
erasing the set speed from memory.
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Setting Cruise Control
Cruise control will not work if the parking brake is set, or
if the master cylinder brake uid level is low.
The cruise control light on the instrument panel cluster
comes on after the cruise control has been set to
the desired speed.
{CAUTION:
If you leave your cruise control on when you are
not using cruise, you might hit a button and go
into cruise when you do not want to. You could be
startled and even lose control. Keep the cruise
control switch off until you want to use cruise
control.
1. Press the
Ibutton.
2. Get up to the desired speed.
3. Press the SET−button located on the steering
wheel and release it.
4. Take your foot off the accelerator.
Resuming a Set Speed
If the cruise control is set at a desired speed and then the
brakes are applied, this shuts off the cruise control. But it
does not need to be reset.
Once the vehicle speed reaches about 25 mph (40 km/h)
or more, press the +RES button on the steering wheel.
The vehicle returns to the previously set speed and stays
there.
Increasing Speed While Using Cruise
Control
To increase the cruise speed while using cruise control:
Press and hold the +RES button on the steering
wheel until the desired speed is reached, then
release it.
To increase vehicle speed in small increments,
press the +RES button. Each time this is done,
the vehicle goes about 1 mph (1.6 km/h) faster.
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Reducing Speed While Using Cruise
Control
To reduce the vehicle speed while using cruise control:
Press and hold the SET– button on the steering
wheel until the desired lower speed is reached,
then release it.
To slow down in very small amounts, press the
SET– button on the steering wheel briey. Each
time this is done, the vehicle goes about 1 mph
(1.6 km/h) slower.
Passing Another Vehicle While Using
Cruise Control
Use the accelerator pedal to increase the vehicle speed.
When you take your foot off the pedal, the vehicle will
slow down to the previous set cruise speed.
Using Cruise Control on Hills
How well the cruise control will work on hills depends
upon the vehicle speed, load, and the steepness of the
hills. When going up steep hills, you might have to step
on the accelerator pedal to maintain the vehicle’s speed.
When going downhill, you might have to brake or shift to
a lower gear to keep the vehicle’s speed down. When the
brakes are applied the cruise control turns off.
Ending Cruise Control
There are three ways to end cruise control:
Step lightly on the brake pedal.
Press the[button on the steering wheel.
Press theIbutton on the steering wheel.
Erasing Speed Memory
The cruise control set speed memory is erased when
the cruise control or the ignition is turned off.
Exterior Lamps
The exterior lamps
control is located on the
instrument panel to the left
of the steering wheel.
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If the warning light comes on and a chime sounds there
could be a brake problem. Have the brake system
inspected right away.
This light can also come on due to low brake uid. See
Brakes on page 5-41for more information.
This light comes on briey when the ignition key is
turned to ON/RUN. If it does not come on then, have it
xed so it is ready to warn if there is a problem.
{CAUTION:
The brake system might not be working properly if
the brake system warning light is on. Driving with
the brake system warning light on can lead to a
crash. If the light is still on after the vehicle has
been pulled off the road and carefully stopped,
have the vehicle towed for service.
If the light comes on while driving, pull off the road and
stop carefully. The pedal might be harder to push or
might go closer to the oor. It can take longer to stop.
If the light is still on, have the vehicle towed for service.
SeeTowing Your Vehicle on page 4-44. United States
Canada
3-41