brakes GMC YUKON XL 2018 User Guide

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
Driving and Operating 197After 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, driveline,
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. See the Maintenance
Schedule 0 370 .
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. { WarningWet 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.
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.
Hydroplaning
Hydroplaning is dangerous. Water
can build up under the vehicle's
tires so they actually ride on the
water. This can happen if the road is wet enough and you are going fast
enough. When the vehicle is
hydroplaning, it has little or no
contact with the road.
There is no hard and fast rule about
hydroplaning. The best advice is to
slow down when the road is wet.
Other Rainy Weather Tips Besides slowing down, other wet
weather driving tips include:
.
Allow extra following distance.
.
Pass with caution.
.
Keep windshield wiping
equipment in good shape.
.
Keep the windshield washer fluid
reservoir filled.
.
Have good tires with proper
tread depth. See Tires 0 320 .
.
Turn off cruise control.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
198 Driving and Operating
Hill and Mountain Roads Driving on steep hills or through
mountains is different than driving
on flat or rolling terrain. Tips include:
.
Keep the vehicle serviced and in
good shape.
.
Check all fluid levels and brakes,
tires, cooling system, and
transmission.
.
Shift to a lower gear when going
down steep or long hills.
{ WarningUsing the brakes to slow the
vehicle on a long downhill slope
can cause brake overheating, can
reduce brake performance, and
could result in a loss of braking.
Shift the transmission to a lower
gear to let the engine assist the
brakes on a steep downhill slope. { WarningCoasting downhill in N (Neutral)
or with the ignition off is
dangerous. This can cause
overheating of the brakes and
loss of steering assist. Always
have the engine running and the
vehicle in gear.
.
Drive at speeds that keep the
vehicle in its own lane. Do not
swing wide or cross the
center line.
.
Be alert on top of hills;
something could be in your lane
(e.g., stalled car, accident).
.
Pay attention to special road
signs (e.g., falling rocks area,
winding roads, long grades,
passing or no-passing zones)
and take appropriate action. Winter Driving Driving on Snow or Ice Snow or ice between the tires and
the road creates less traction or
grip, so drive carefully. Wet ice can
occur at about 0 °C (32 °F) when
freezing rain begins to fall. Avoid
driving on wet ice or in freezing rain
until roads can be treated.
For Slippery Road Driving:
.
Accelerate gently. Accelerating
too quickly causes the wheels to
spin and makes the surface
under the tires slick.
.
Turn on Traction Control. See
Traction Control/Electronic
Stability Control 0 229 .
.
The Antilock Brake System
(ABS) improves vehicle stability
during hard stops, but the
brakes should be applied sooner
than when on dry pavement.
See Antilock Brake System
(ABS) 0 227 .

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
206 Driving and Operating To shift out of P (Park), the ignition
must be on or in ACC/
ACCESSORY, and the brake pedal
must be applied.
Stopping the Engine/LOCK/
OFF (No Indicator Lights) : When
the vehicle is stopped, press
ENGINE START/STOP once to turn
the engine off.
If the vehicle is in P (Park), the
ignition will turn off, and Retained
Accessory Power (RAP) will remain
active. See Retained Accessory
Power (RAP) 0 212 .
If the vehicle is not in P (Park), the
ignition will return to ACC/
ACCESSORY and display the
message SHIFT TO PARK in the
Driver Information Center (DIC).
When the vehicle is shifted into
P (Park), the ignition system will
turn off.
Do not turn the engine off when the
vehicle is moving. This will cause a
loss of power assist in the brake
and steering systems and disable
the airbags. The vehicle may have an electric
steering column lock. The lock is
activated when the ignition is turned
off and either front door is opened.
A sound may be heard as the lock
actuates or releases. The steering
column lock may not release with
the wheels turned off center. If this
happens, the vehicle may not start.
Move the steering wheel from left to
right while attempting to start the
vehicle. If this does not work, the
vehicle needs service.
If the vehicle must be shut off in an
emergency:
1. Brake using a firm and steady
pressure. 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 off. On vehicles with an automatic transmission, the
shift lever must be in P (Park)
to turn the ignition off.
4. Set the parking brake. See
Parking Brake 0 228 .
{ WarningTurning 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,
press and hold ENGINE START/
STOP for longer than two seconds,
or press twice in five seconds.
ACC/ACCESSORY (Amber
Indicator Light) : This mode allows
some electrical accessories to be
used when the engine is off.
With the ignition off, pressing the
button one time without the brake
pedal applied will place the ignition
system in ACC/ACCESSORY.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
Driving and Operating 207The ignition will switch from ACC/
ACCESSORY to off after
five minutes to prevent battery
rundown.
ON/RUN/START (Green Indicator
Light) : This mode is for driving and
starting. With the ignition off, and
the brake pedal applied, pressing
the button once will turn the ignition
on. Once engine cranking begins,
release the button. Engine cranking
will continue until the engine starts.
See Starting the Engine 0 209 .
Service Mode
This power mode is available for
service and diagnostics, and to
verify the proper operation of the
malfunction indicator lamp as may
be required for emission inspection
purposes. With the vehicle off, and
the brake pedal not applied,
pressing and holding the button for
more than five seconds will place
the vehicle in Service Mode. The
instruments and audio systems will
operate as they do when the ignition
is on, but the vehicle will not be able to be driven. The engine will not
start in Service Mode. Press the
button again to turn the ignition off.
Ignition Positions (Key
Access)
Vehicles with Key Access have an
ignition switch with four different
positions.
To shift out of P (Park), the ignition
must be on or in ACC/ACCESSORY
and the regular brake pedal must be
applied.
0 (STOPPING THE ENGINE/LOCK/
OFF) : When the vehicle is stopped,
turn the ignition switch to LOCK/ OFF to turn the engine off. Retained
Accessory Power (RAP) will remain
active. See Retained Accessory
Power (RAP) 0 212 .
This position locks the ignition and
steering wheel. It also locks the
transmission on automatic
transmission vehicles. The key can
be removed in LOCK/OFF.
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
does not work, then the vehicle
needs service.
Do not turn the engine off when the
vehicle is moving. This will cause a
loss of power assist in the brake
and steering systems and disable
the airbags.
If the vehicle must be shut off in an
emergency:
1. Brake using a firm and steady
pressure. Do not pump the
brakes repeatedly. This may
deplete power assist, requiring
increased brake pedal force.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
208 Driving and Operating 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 0 228 .
{ 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.
CautionUsing 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.
1 (ACC/ACCESSORY) : This
position lets things like the radio
and the windshield wipers operate
while the engine is off. It also
unlocks the steering wheel. Use this
position if the vehicle must be
pushed or towed.
2 (ON/RUN) : This position can be
used to operate the electrical
accessories and to display some
instrument 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.
The switch stays in this position
when the engine is running. The
transmission is also unlocked in this
position on automatic transmission
vehicles.
If the key is left in the ACC/
ACCESSORY or ON/RUN position
with the engine off, the battery could
be drained. The vehicle may not
start if the battery is allowed to drain
for an extended period of time.
3 (START) : This is the position that
starts the engine. When the engine
starts, release the key. The ignition
switch returns to ON/RUN for
driving.
A warning tone will sound when the
driver door is opened and the
ignition is in ACC/ACCESSORY or
LOCK/OFF, and the key is in the
ignition.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
218 Driving and Operating 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 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.
L : This position allows selection of
a range of gears appropriate for
current driving conditions.
If equipped, see “ Range Selection
Mode ” under Manual Mode 0 218 .
Caution
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 the vehicle
is stuck, do not spin the tires.
(Continued) Caution (Continued) When stopping on a hill, use the
brakes to hold the vehicle in
place.
Normal Mode Grade Braking This mode is enabled when the
vehicle is started, but is not enabled
in Range Selection Mode. It assists
in maintaining desired vehicle
speeds when driving on downhill
grades by using the engine and
transmission to slow the vehicle.
The first time the system engages
for each ignition cycle, a DIC
message will be displayed.
To disable or enable Normal Mode
Grade Braking within the current
ignition cycle, press and hold the
Tow/Haul button for five seconds.
When the button is released, the
requested mode change is made.
A DIC message displays.
For other forms of grade braking,
see Tow/Haul Mode 0 222 and
Cruise Control 0 233 . Kickdown Mode The accelerator pedal provides an
additional downshift after pressing
through the kickdown feature.
It requires extra pedal pressure near
the end of its travel to engage.
Manual Mode Range Selection Mode
If equipped, Range Selection Mode
helps control the vehicle's
transmission and vehicle speed
while driving downhill or towing a
trailer by letting you select a desired
range of gears.
To use this feature:
1. Move the shift lever to
L (Manual Mode).

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
Driving and Operating 22110 Speed Transmission Gear before shifting from
D (Drive) to L (Manual Mode) 10th 9th 8th 7th 6th 5th 4th 3rd 2nd 1st
Range after shifting from
D (Drive) to L (Manual
Mode) - Tow/Haul not engaged L7 L7 L7 L6 L5 L4 L3 L3 L2 L1
Range after shifting from
D (Drive) to L (Manual
Mode) - Tow/Haul engaged L7 L7 L6 L5 L4 L3 L3 L3 L2 L1
Grade Braking is not available when
Range Selection Mode is active.
See Tow/Haul Mode 0 222 .
While using Range Selection Mode,
cruise control and the Tow/Haul
Mode can be used.
Caution
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 the vehicle
(Continued) Caution (Continued) is stuck, do not spin the tires.
When stopping on a hill, use the
brakes to hold the vehicle in
place.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
Driving and Operating 227Shifting Into 4
m or AUTO
Turn the knob to the 4
m or AUTO
position. This can be done at any
speed. The indicator light will flash
while shifting. It will remain on when
the shift is completed.
Shifting Into 2
mTurn the knob to the 2
m position.
This can be done at any speed. The
indicator light will flash while
shifting. It will remain on when the
shift is completed. Brakes Antilock Brake
System (ABS) This vehicle has an Antilock Brake
System (ABS), an advanced
electronic braking system that helps
prevent a braking skid.
When the vehicle begins to drive
away, ABS checks itself.
A momentary motor or clicking noise
may be heard while this test is going
on, and it may even be noticed that
the brake pedal moves a little. This
is normal.
If there is a problem with ABS, this
warning light stays on. See Antilock
Brake System (ABS) Warning Light
0 145 . If driving safely on a wet road and it
becomes necessary to slam on the
brakes and continue braking to
avoid a sudden obstacle, a
computer senses the wheels are
slowing down. If one of the wheels
is about to stop rolling, the computer
will separately work the brakes at
each wheel.
ABS can change the brake pressure
to each wheel, as required, faster
than any driver could. This can help
you steer around the obstacle while
braking hard.
As the brakes are applied, the
computer keeps receiving updates
on wheel speed and controls
braking pressure accordingly.
Remember: ABS does not change
the time needed to get a foot up to
the brake pedal or always decrease
stopping distance. If you get too
close to the vehicle in front of you,
there will not be enough time to
apply the brakes if that vehicle
suddenly slows or stops. Always
leave enough room up ahead to
stop, even with ABS.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
228 Driving and Operating Using ABS Do not pump the brakes. Just hold
the brake pedal down firmly and let
ABS work. You may hear the ABS
pump or motor operating and feel
the brake pedal pulsate. This is
normal.
Braking in Emergencies ABS allows you to steer and brake
at the same time. In many
emergencies, steering can help
more than even the very best
braking. Parking Brake
Set the parking brake by holding the
regular brake pedal down, then
pushing down the parking brake
pedal.
If the ignition is on, the brake
system warning light will come on.
See Brake System Warning Light
0 145 . CautionDriving with the parking brake on
can overheat the brake system
and cause premature wear or
damage to brake system parts.
Make sure that the parking brake
is fully released and the brake
warning light is off before driving.
To release the parking brake, hold
the regular brake pedal down, then
push down momentarily on the
parking brake pedal until you feel
the pedal release. Slowly pull your
foot up off the parking brake pedal.
If the parking brake is not released
when you begin to drive, a DIC
message will appear and a chime
will sound warning you that the
parking brake is still on.
Brake Assist The Brake Assist feature is
designed to assist the driver in
stopping or decreasing vehicle
speed in emergency driving
conditions. This feature uses the
stability system hydraulic brake

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-11349262) - 2018 - crc - 6/21/17
Driving and Operating 229control module to supplement the
power brake system under
conditions where the driver has
quickly and forcefully applied the
brake pedal in an attempt to quickly
stop or slow down the vehicle. The
stability system hydraulic brake
control module increases brake
pressure at each corner of the
vehicle until the ABS activates.
Minor brake pedal pulsation or
pedal movement during this time is
normal and the driver should
continue to apply the brake pedal as
the driving situation dictates. The
Brake Assist feature will
automatically disengage when the
brake pedal is released or brake
pedal pressure is quickly
decreased.
Hill Start Assist (HSA) Vehicles with StabiliTrak have a Hill
Start Assist (HSA) feature, which
may be useful when the vehicle is
stopped on a grade. This feature is
designed to prevent the vehicle from
rolling, either forward or rearward,
during vehicle drive off. After the
driver completely stops and holds the vehicle in a complete standstill
on a grade, HSA will be
automatically activated. During the
transition period between when the
driver releases the brake pedal and
starts to accelerate to drive off on a
grade, HSA holds the braking
pressure for a maximum of
two seconds to ensure that there is
no rolling. The brakes will
automatically release when the
accelerator pedal is applied within
the two-second window. If the
vehicle is equipped with the
Integrated Trailer Brake Control
(ITBC) system, HSA may also apply
the trailer brakes. It will not activate
if the vehicle is in a drive gear and
facing downhill or if the vehicle is
facing uphill and in R (Reverse).
There may be situations on minor
hills (less than 5% grade) with a
loaded vehicle or while pulling a
trailer where HSA may activate. Ride Control Systems Traction Control/
Electronic Stability
Control System Operation The vehicle has a Traction Control
System (TCS) and StabiliTrak ®
, an
electronic stability control system.
These systems help limit wheel spin
and assist the driver in maintaining
control, especially on slippery road
conditions.
TCS activates if it senses that any
of the drive wheels are spinning or
beginning to lose traction. When this
happens, TCS applies the brakes to
the spinning wheels and reduces
engine power to limit wheel spin.
StabiliTrak activates when the
vehicle senses a difference between
the intended path and the direction
the vehicle is actually traveling.
StabiliTrak selectively applies
braking pressure to any one of the
vehicle wheel brakes to assist the
driver in keeping the vehicle on the