2012 GMC YUKON brake light

Black plate (38,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-38 Instruments and Controls
Battery Voltage and
Charging Messages
BATTERY LOW START
VEHICLE
When the vehicle’s battery is
severely discharged, this message
will display and four chimes will
sound. Start the vehicle
immediately. If the vehicle is not
started and the battery continues to
discharge, the climate controls,
heated seats, and audio systems
will shut off and the vehicle may
require a jump start. These systems
will function again after the vehicle
is started.
SERVICE BATTERY
CHARGING SYSTEM
On some vehicles, this message
displays if there is a problem with
the battery charging system. Under
certain conditions, the charging
system light may also turn on in the
instrument panel cluster. See
Charging System Light on
page 5‑20. Driving with this problem could drain the battery. Turn off all
unnecessary accessories. Have the
electrical system checked as soon
as possible. See your dealer.
Brake System Messages
SERVICE BRAKE SYSTEM
This message displays along with
the brake system warning light if
there is a problem with the brake
system. See
Brake System Warning
Light on page 5‑23. 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 as soon as
possible. See your dealer.
SERVICE BRAKES SOON
This message displays if there is a
problem with the brake system.
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 TRAILER BRAKE
SYSTEM
On vehicles with the Integrated
Trailer Brake Control (ITBC) system,
this message displays and a chime
sounds when there is a problem
with the ITBC system.
When this message displays, power
is no longer available to the trailer
brakes.
As soon as it is safe to do so,
carefully pull your vehicle over to
the side of the road and turn the
ignition off. Check the wiring
connection to the trailer and turn the
ignition back on. If this message still
displays, either your vehicle or the
trailer needs service. See your
dealer.

Black plate (44,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-44 Instruments and Controls
page 9‑15. To turn the StabiliTrak
system on or off, seeStabiliTrak®
System on page 9‑46.
STABILITRAK OFF may also
display when the stability control
has been automatically disabled.
There are several conditions that
can cause this message to appear.
.One condition is overheating,
which could occur if StabiliTrak
activates continuously for an
extended period of time.
.The message also displays if the
brake system warning light is on.
SeeBrake System Warning
Light on page 5‑23.
.The message could display if the
stability system takes longer
than usual to complete its
diagnostic checks due to driving
conditions.
.The message displays if an
engine or vehicle related
problem has been detected and
the vehicle needs service. See
your dealer. The message turns off as soon as
the conditions that caused the
message to be displayed are no
longer present.
Airbag System Messages
SERVICE AIR BAG
This message displays if there is a
problem with the airbag system.
Have your dealer inspect the
system for problems. See
Airbag
Readiness Light on page 5‑18 and
Airbag System on page 3‑30 for
more information.
Anti-theft Alarm System
Messages
SERVICE THEFT DETERRENT
SYSTEM
This message displays when there
is a problem with the theft-deterrent
system. The vehicle may or may not
restart so you may want to take the
vehicle to your dealer before turning off the engine. See
Immobilizer
Operation on page 2‑15 for more
information.
Tire Messages
SERVICE TIRE MONITOR
SYSTEM
On vehicles with the Tire Pressure
Monitor System (TPMS), this
message displays if a part on the
TPMS is not working properly. The
tire pressure light also flashes and
then remains on during the same
ignition cycle. See Tire Pressure
Light on page 5‑26. Several
conditions may cause this message
to appear. See Tire Pressure
Monitor Operation on page 10‑59 for
more information. If the warning
comes on and stays on, there may
be a problem with the TPMS. See
your dealer.
TIRE LEARNING ACTIVE
On vehicles with the Tire Pressure
Monitor System (TPMS), this
message displays when the TPMS

Black plate (8,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-8 Driving and Operating
When driving on hills:
.Use a low gear and keep a firm
grip on the steering wheel.
.Maintain a slow speed.
.When possible, drive straight up
or down the hill.
.Slow down when approaching
the top of the hill.
.Use headlamps even during the
day to make the vehicle more
visible.
{WARNING
Driving to the top of a hill at high
speed can cause an accident.
There could be a drop-off,
embankment, cliff, or even
another vehicle. You could be
seriously injured or killed. As you
near the top of a hill, slow down
and stay alert.
.Never go downhill forward or
backward with either the
transmission or transfer case in
N (Neutral). The brakes could
overheat and you could lose
control.
{WARNING
If the vehicle has the two‐speed
automatic transfer case, shifting
the transfer case to N (Neutral)
can cause your vehicle to roll
even if the transmission is in
P (Park). This is because the
N (Neutral) position on the
transfer case overrides the
transmission. You or someone
else could be injured. If leaving
the vehicle, set the parking brake
and shift the transmission to
P (Park). Shift the transfer case to
any position but N (Neutral).
.When driving down a hill, keep
the vehicle headed straight
down. Use a low gear because
the engine will work with the
brakes to slow the vehicle and
help keep the vehicle under
control.
{WARNING
Heavy braking when going down
a hill can cause your brakes to
overheat and fade. This could
cause loss of control and you or
others could be injured or killed.
Apply the brakes lightly when
descending a hill and use a low
gear to keep vehicle speed under
control.
If the vehicle stalls on a hill:
1. Apply the brakes to stop the vehicle, and then apply the
parking brake.

Black plate (11,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-11
After Off-Road Driving
Remove any brush or debris that
has collected on the underbody,
or chassis, or under the hood.
These accumulations can be a fire
hazard.
After operation in mud or sand,
have the brake linings cleaned and
checked. These substances can
cause glazing and uneven braking.
Check the body structure, steering,
suspension, wheels, tires, and
exhaust system for damage and
check the fuel lines and cooling
system for any leakage.
More frequent maintenance
service is required. Refer to the
Maintenance Schedule for more
information.
Driving on Wet Roads
Rain and wet roads can reduce
vehicle traction and affect your
ability to stop and accelerate.
Always drive slower in these types
of driving conditions and avoid
driving through large puddles and
deep‐standing or flowing water.
{WARNING
Wet brakes can cause crashes.
They might not work as well in a
quick stop and could cause
pulling to one side. You could
lose control of the vehicle.
After driving through a large
puddle of water or a car/vehicle
wash, lightly apply the brake
pedal until the brakes work
normally.(Continued)
WARNING (Continued)
Flowing or rushing water creates
strong forces. Driving through
flowing water could cause the
vehicle to be carried away. If this
happens, you and other vehicle
occupants could drown. Do not
ignore police warnings and be
very cautious about trying to drive
through flowing water.

Black plate (23,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-23
If the vehicle must be shut off in an
emergency:
1. Brake using a firm and steadypressure. Do not pump the
brakes repeatedly. This may
deplete power assist, requiring
increased brake pedal force.
2. Shift the vehicle to N (Neutral). This can be done while the
vehicle is moving. After shifting
to N (Neutral), firmly apply the
brakes and steer the vehicle to a
safe location.
3. Come to a complete stop, shift to P (Park), and turn the ignition
to LOCK/OFF. On vehicles with
an automatic transmission, the
shift lever must be in P (Park) to
turn the ignition switch to the
LOCK/OFF position.
4. Set the parking brake. See Parking Brake on page 9‑45.{WARNING
Turning off the vehicle while
moving may cause loss of power
assist in the brake and steering
systems and disable the airbags.
While driving, only shut the
vehicle off in an emergency.
If the vehicle cannot be pulled over,
and must be shut off while driving,
turn the ignition to ACC/
ACCESSORY.
The steering can bind with the
wheels turned off center. If this
happens, move the steering wheel
from right to left while turning the
key to ACC/ACCESSORY. If this
doesn't work, then the vehicle needs
service. Notice:
Using a tool to force the
key to turn in the ignition could
cause damage to the switch or
break the key. Use the correct
key, make sure it is all the way in,
and turn it only with your hand.
If the key cannot be turned by
hand, see your dealer.
B (ACC/ACCESSORY): This
position lets things like the radio
and the windshield wipers operate
while the engine is off. Use this
position if the vehicle must be
pushed or towed.
C (ON/RUN): This position can be
used to operate the electrical
accessories and to display some
instrument panel cluster warning
and indicator lights. This position
can also be used for service and
diagnostics, and to verify the proper
operation of the malfunction
indicator lamp as may be required
for emission inspection purposes.

Black plate (31,1)GMC Yukon/Yukon XL Owner Manual - 2012
Driving and Operating 9-31
{WARNING
It can be dangerous to get out of
the vehicle if the automatic
transmission shift lever is not fully
in P (Park) with the parking brake
firmly set. The vehicle can roll. Do
not leave the 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 the
vehicle will not move, even when
you are on fairly level ground,
always set the parking brake and
move the shift lever to P (Park).
{WARNING
If the vehicle has a four-wheel
drive transfer case with a
N (Neutral) position, and the
transfer case is in N (Neutral), the
vehicle may roll, even if the
automatic transmission shift lever
is in P (Park). So, be sure the
transfer case is in a drive
gear—not in N (Neutral). Always
set the parking brake.
Follow the proper steps to be sure
the vehicle will not move. See
Shifting Into Park on page 9‑27.
If parking on a hill and pulling a
trailer, see Driving Characteristics
and Towing Tips on page 9‑68.
Automatic
Transmission
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
If the 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.
Heavy Duty 6-Speed Automatic
Transmission Shown (Light Duty Similar)
See “Range Selection Mode” under
Manual Mode on page 9‑35.

Black plate (36,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-36 Driving and Operating
Tow/Haul Mode
The vehicle has a Tow/Haul Mode.
The selector button is located on the
end of the column shift lever. You
can use this feature to assist when
driving down steep hills or mountain
grades, towing, or hauling a heavy
load, or if there is a need to charge
a battery installed in a trailer. See
Towing Equipment on page 9‑76
andHill and Mountain Roads on
page 9‑13 for more information.
When Tow/Haul Mode is selected
the tow/haul indicator light will come
on. SeeTow/Haul Mode Light on
page 5‑25.
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 Continuous Damping Control
(CDC) on page 9‑50.
Grade Braking (Hydra-Matic®
6-Speed Automatic
Transmission)
The Grade Braking shift modes can
be activated by pressing the button
on the end of the shift control lever.
While in Range Selection Mode,
Grade Braking is deactivated
allowing the driver to select a
desired range of gears. Grade Braking is only active while
the Tow/Haul Mode is selected and
you are not in the Range Selection
Mode. See
“Tow/Haul Mode” listed
previously and Manual Mode on
page 9‑35 for more information on
the Range Selection Mode. Grade
Braking assists in maintaining
desired vehicle speeds when driving
on downhill grades by automatically
implementing a shift schedule that
utilizes the engine and transmission
to slow the vehicle. This reduces
wear on the braking system and
increases control of the vehicle.
Grade Braking monitors vehicle
speed, acceleration, engine torque
and brake pedal usage. Using this
information, it detects when the
truck is on a downhill grade and the
driver desires to slow the vehicle by
pressing the brake.
Also see Towing Equipment on
page 9‑76 for more information.

Black plate (38,1)GMC Yukon/Yukon XL Owner Manual - 2012
9-38 Driving and Operating
If the lights do not come on, you
should take the vehicle to your
dealer for service. An indicator light
will flash while shifting. It will stay on
when the shift is completed. If for
some reason the transfer case
cannot make a requested shift, it will
return to the last chosen setting.
2
m(Two-Wheel Drive High):This
setting is used for driving in most
street and highway situations. The
front axle is not engaged in
two-wheel drive. This setting also
provides the best fuel economy.
AUTO (Automatic Four-Wheel
Drive): This setting is ideal for use
when road surface traction
conditions are variable. When
driving the vehicle in AUTO, the
front axle is engaged, and the
vehicle's power is sent to the front
and rear wheels automatically
based on driving conditions. Driving
in this mode results in slightly lower
fuel economy than Two-Wheel
Drive High. 4
m(Four-Wheel Drive High):
Use
the Four-Wheel Drive High position
when you need extra traction, such
as on snowy or icy roads or in most
off-road situations. This setting also
engages your front axle to help
drive the vehicle. This is the best
setting to use when plowing snow.
4
n(Four-Wheel Drive Low): This
setting also engages the front axle
and delivers extra torque. You may
never need this setting. It sends
maximum power to all four wheels.
You might choose Four-Wheel Drive
Low if you are driving off-road in
deep sand, deep mud, deep snow,
and while climbing or descending
steep hills.
The vehicle has StabiliTrak. Shifting
into Four-Wheel Drive Low will turn
Traction Control and StabiliTrak off.
See StabiliTrak
®System on
page 9‑46.
{WARNING
Shifting the transfer case to
N (Neutral) can cause the vehicle
to roll even if the transmission is
in P (Park). You or someone else
could be seriously injured. Be
sure to set the parking brake
before placing the transfer case in
N (Neutral). See Parking Brake on
page 9‑45.
N (Neutral): Shift the vehicle's
transfer case to N (Neutral) only
when towing the vehicle. See
Recreational Vehicle Towing on
page 10‑93 orTowing the Vehicle
on page 10‑93 for more information.
If the SERVICE 4 WHEEL DRIVE
message stays on, you should take
the vehicle to your dealer for
service. See “SERVICE 4 WHEEL
DRIVE” message under
Transmission Messages on
page 5‑45.