engine GMC YUKON XL 2015 Repair Manual

Black plate (25,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Driving and Operating 9-25
Driver Information Center (DIC),
hold the ignition switch in the
START position to continue
engine cranking.
{Caution
Cranking the engine for long
periods of time, by returning the
ignition to the START position
immediately after cranking has
ended, can overheat and damage
the cranking motor, and drain the
battery. Wait at least 15 seconds
between each try, to let the
cranking motor cool down.2. If the engine does not start after
five to 10 seconds, especially
in very cold weather (below
−18°C or 0°F), it could be
flooded with too much gasoline.
Try pushing the accelerator
pedal all the way to the floor and
holding it there while holding the
key in START for up to
15 seconds. Wait at least
15 seconds between each try, to
allow the cranking motor to cool
down. When the engine starts,
let go of the key and accelerator.
If the vehicle starts briefly but
then stops again, do the same
thing. This clears the extra
gasoline from the engine. Do not
race the engine immediately
after starting it. Operate the
engine and transmission gently
until the oil warms up and
lubricates all moving parts.
Starting Procedure (Keyless
Access)
1. With the Keyless Access
system, the RKE transmitter
must be in the vehicle. Press the
ENGINE START/STOP button
with the brake pedal applied.
When the engine begins
cranking, let go of the button.
The idle speed will go down as
the engine gets warm. Do not
race the engine immediately
after starting it.
If the RKE transmitter is not in
the vehicle, if there is
interference, or the RKE battery
is low, the Driver Information
Center (DIC) will display a
message. See Key and Lock
Messages on page 5-35.

Black plate (26,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
9-26 Driving and Operating
{Caution
Cranking the engine for long
periods of time, by returning the
ignition to the START position
immediately after cranking has
ended, can overheat and damage
the cranking motor, and drain the
battery. Wait at least 15 seconds
between each try, to let the
cranking motor cool down.
2. If the engine does not start after five to 10 seconds, especially in
very cold weather (below −18°C
or 0°F), it could be flooded with
too much gasoline. Try pushing
the accelerator pedal all the way
to the floor and holding it there
as you press the ENGINE
START/STOP button, for up to a
maximum of 15 seconds. Wait at
least 15 seconds between each
try, to allow the cranking motor
to cool down. When the engine
starts, let go of the button, and
the accelerator. If the vehicle starts briefly but then stops
again, do the same thing. This
clears the extra gasoline from
the engine. Do not race the
engine immediately after starting
it. Operate the engine and
transmission gently until the oil
warms up and lubricates all
moving parts.
Engine Heater
The engine coolant heater can
provide easier starting and better
fuel economy during engine
warm-up in cold weather conditions
at or below
−18°C (0°F). Vehicles
with an engine heater should be
plugged in at least four hours before
starting. There may be an internal
thermostat in the plug end of the
cord, which will prevent engine
coolant heater operation at
temperatures above −18°C (0°F).
To Use the Engine Coolant
Heater
1. Turn off the engine. 2. Open the hood and unwrap the
electrical cord. The cord is by
the left front fender, next to the
engine compartment fuse block.
Check the heater cord for
damage. If it is damaged, do not
use it. See your dealer for a
replacement. Inspect the cord for
damage yearly.
3. Plug the cord into a normal, grounded 110-volt AC outlet.
{Warning
Improper use of the heater cord
or an extension cord can damage
the cord and may result in
overheating and fire.
.Plug the cord into a
three-prong electrical utility
receptacle that is protected
by a ground fault detection
(Continued)

Black plate (27,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Driving and Operating 9-27
Warning (Continued)
function. An ungrounded
outlet could cause an electric
shock.
.Use a weatherproof,
heavy-duty, 15 amp-rated
extension cord if needed.
Failure to use the
recommended extension cord
in good operating condition,
or using a damaged heater or
extension cord, could make it
overheat and cause a fire,
property damage, electric
shock, and injury.
.Do not operate the vehicle
with the heater cord
permanently attached to the(Continued)
Warning (Continued)
vehicle. Possible heater cord
and thermostat damage could
occur.
.While in use, do not let the
heater cord touch vehicle
parts or sharp edges. Never
close the hood on the
heater cord.
.Before starting the vehicle,
unplug the cord, reattach the
cover to the plug, and
securely fasten the cord.
Keep the cord away from any
moving parts.
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. The length of time the heater should
remain plugged in depends on
several factors. Ask a dealer in the
area where you will be parking the
vehicle for the best advice on this.
Retained Accessory
Power (RAP)
The following vehicle accessories
can be used for up to 10 minutes
after the engine is turned off:
.Audio System
.Power Windows
.OnStar System (if equipped)
.Sunroof (if equipped)
.Accessory Power Outlets. The
console and center seat outlets
are RAP powered.
These features work when the key
is in ON/RUN or ACC/
ACCESSORY. Once the key is
turned from ON/RUN to LOCK/OFF,
the windows and sunroof continue
to work up to 10 minutes until any

Black plate (28,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
9-28 Driving and Operating
door is opened. The radio continues
to work for up to 10 minutes or until
the driver door is opened.
Shifting Into Park
{Warning
It can be dangerous to get out of
the vehicle if the shift lever is not
fully in P (Park) with the parking
brake firmly set. The vehicle can
roll. 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, use the steps
that follow. 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 will be free to roll,
even if the shift lever is in
P (Park). Be sure the transfer(Continued)
Warning (Continued)
case is in a drive gear. If towing a
trailer, seeDriving Characteristics
and Towing Tips on page 9-74.
1. Hold the brake pedal down, then set the parking brake.
See Parking Brake on
page 9-42.
2. Move the shift lever into the P (Park) position by pulling the
shift lever toward you and
moving it up as far as it will go.
3. Be sure the transfer case is in a drive gear —not in N (Neutral).
4. Turn the ignition key to LOCK/OFF.
5. Remove the key and take it with you. If you can leave the vehicle
with the ignition key in your
hand, the vehicle is in P (Park).
Leaving the Vehicle with the
Engine Running
{Warning
It can be dangerous to leave the
vehicle with the engine running.
The vehicle could move suddenly
if the shift lever is not fully in
P (Park) with the parking brake
firmly set.
If you have four-wheel drive and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). So be sure the transfer
case is in a drive gear —not in
N (Neutral).
And, if you leave the vehicle with
the engine running, it could
overheat and even catch fire. You
or others could be injured. Do not
leave the vehicle with the engine
running unless you have to.

Black plate (29,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Driving and Operating 9-29
If you have to leave the vehicle with
the engine running, be sure the
vehicle is in P (Park) and the
parking brake is firmly set before
you leave it. After you move the shift
lever into P (Park), hold the regular
brake pedal down. Then, see if you
can move the shift lever away from
P (Park) without first pulling it toward
you. If you can, it means that the
shift lever was not fully locked into
P (Park).
Torque Lock
If you are parking on a hill and you
do not shift the transmission into
P (Park) properly, the weight of the
vehicle may put too much force on
the parking pawl in the
transmission. You may find it difficult
to pull the shift lever out of P (Park).
This is called torque lock. To
prevent torque lock, set the parking
brake and then shift into P (Park)
properly before you leave the driver
seat. To find out how, seeShifting
Into Park on page 9-28. When you are ready to drive, move
the shift lever out of P (Park) 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. You will then be
able to pull the shift lever out of
P (Park).
Shifting out of Park
This vehicle is equipped with an
electronic shift lock release system.
The shift lock release is
designed to:
.Prevent ignition key removal
unless the shift lever is in
P (Park).
.Prevent movement of the shift
lever out of P (Park), unless the
ignition is in ON/RUN and the
regular brake pedal is applied.
The shift lock release is always
functional except in the case of an
uncharged or low voltage (less than
9 volt) battery.
If the vehicle has an uncharged
battery or a battery with low voltage,
try charging or jump starting the
battery. See
Jump Starting on
page 10-78.
To shift out of P (Park):
1. Apply the brake pedal.
2. Move the shift lever to the desired position.
If you still are unable to shift out of
P (Park):
1. Ease the pressure on the shift lever.
2. While holding down the brake pedal, press the shift lever all
the way into P (Park).
3. Move the shift lever to the desired position.
If you are still having a problem
shifting, then have the vehicle
serviced soon.

Black plate (30,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
9-30 Driving and Operating
Parking over Things
That Burn
{Warning
Things that can burn could touch
hot exhaust parts under the
vehicle and ignite. Do not park
over papers, leaves, dry grass,
or other things that can burn.
Active Fuel Management®
Vehicles with V8 engines may have
Active Fuel Management. This
system allows the engine to operate
on either all or half of its cylinders,
depending on the driving conditions.When less power is required, such
as cruising at a constant vehicle
speed, the system will operate in
the half cylinder mode, allowing the
vehicle to achieve better fuel
economy. When greater power
demands are required, such as
accelerating from a stop, passing,
or merging onto a freeway, the
system will maintain full-cylinder
operation.
If the vehicle has an Active Fuel
Management indicator, see
Driver
Information Center (DIC) on
page 5-28 for more information on
using this display.
Engine Exhaust
{Warning
Engine exhaust contains carbon
monoxide (CO) which cannot be
seen or smelled. Exposure to CO
can cause unconsciousness and
even death.
Exhaust may enter the vehicle if:
.The vehicle idles in areas
with poor ventilation (parking
garages, tunnels, deep snow
that may block underbody
airflow or tail pipes).
.The exhaust smells or
sounds strange or different.
.The exhaust system leaks
due to corrosion or damage.
.The vehicle exhaust system
has been modified, damaged,
or improperly repaired.
(Continued)

Black plate (31,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Driving and Operating 9-31
Warning (Continued)
.There are holes or openings
in the vehicle body from
damage or aftermarket
modifications that are not
completely sealed.
If unusual fumes are detected or
if it is suspected that exhaust is
coming into the vehicle:
.Drive it only with the windows
completely down.
.Have the vehicle repaired
immediately.
Never park the vehicle with the
engine running in an enclosed
area such as a garage or a
building that has no fresh air
ventilation.
Running the Vehicle
While Parked
It is better not to park with the
engine running.
If the vehicle is left with the engine
running, follow the proper steps to
be sure the vehicle will not move.
See Shifting Into Park on page 9-28
and Engine Exhaust on page 9-30.
If parking on a hill and pulling a
trailer, see Driving Characteristics
and Towing Tips on page 9-74.
Automatic
Transmission
If equipped, there is an electronic
shift lever position indicator within
the instrument 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.
See “Range Selection Mode” under
Manual Mode on page 9-34.
P (Park): This position locks the
rear wheels. It is the best position to
use when starting the engine
because the vehicle cannot move
easily. When parked on a hill,
especially when the vehicle has a
heavy load, you might notice an

Black plate (32,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
9-32 Driving and Operating
increase in the effort to shift out of
P (Park). See“Torque Lock” under
Shifting Into Park on page 9-28.
{Warning
It is dangerous to get out of the
vehicle if the 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. 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).
See Shifting Into Park on
page 9-28 andDriving
Characteristics and Towing Tips
on page 9-74.
R (Reverse): Use this gear to
back up.
{Caution
Shifting to R (Reverse) while the
vehicle is moving forward could
damage the transmission. The
repairs would not be covered by
the vehicle warranty. Shift to
R (Reverse) only after the vehicle
is stopped.
To rock the vehicle back and forth to
get out of snow, ice, or sand without
damaging the transmission, see If
the Vehicle Is Stuck on page 9-13.
N (Neutral): In this position, the
engine does not connect with the
wheels. To restart when you are
already moving, use N (Neutral)
only. Also, use N (Neutral) when the
vehicle is being towed.
{Warning
Shifting into a drive gear while the
engine is running at high speed is
dangerous. Unless your foot is
firmly on the brake pedal, the
vehicle could move very rapidly.
You could lose control and hit
people or objects. Do not shift
into a drive gear while the engine
is running at high speed.
{Caution
Shifting out of P (Park) or
N (Neutral) with the engine
running at high speed may
damage the transmission. The
repairs would not be covered by
the vehicle warranty. Be sure the
engine is not running at high
speed when shifting the vehicle.

Black plate (33,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Driving and Operating 9-33
D (Drive):This position is for
normal driving. It provides the best
fuel economy. If you need more
power for passing, and you are:
.Going less than about 55 km/h
(35 mph), push the accelerator
pedal about halfway down.
.Going about 55 km/h (35 mph) or
more, push the accelerator all
the way down.
By doing this, the vehicle shifts
down to the next gear and has
more power.
Use D (Drive) and Tow/Haul Mode
when towing a trailer, carrying a
heavy load, driving on steep hills,
or driving off-road. 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”under
Loss of Control on page 9-5. The 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 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 transmission uses adaptive
shift controls. The adaptive shift
control process continually
compares key shift parameters to
pre-programmed ideal shifts stored
in the transmission’s computer. The
transmission constantly makes
adjustments to improve vehicle
performance according to how thevehicle 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 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
allows selection of a range of gears
appropriate for current driving
conditions. If equipped, see “Range
Selection Mode” underManual
Mode on page 9-34.
{Caution
Spinning the tires or holding the
vehicle in one place on a hill
using only the accelerator pedal
(Continued)

Black plate (34,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
9-34 Driving and Operating
Caution (Continued)
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.
Normal Mode Grade Braking
If equipped with a gasoline engine
and an automatic transmission,
Normal Mode Grade Braking 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 key cycle, a DIC message
will be displayed. SeeTransmission
Messages on page 5-41. To disable or enable Normal Mode
Grade Braking within the current
ignition key 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. See
Transmission
Messages on page 5-41.
For other forms of grade braking,
see Tow/Haul Mode on page 9-36
and Cruise Control on page 9-47.
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
M (Manual Mode).
2. Press the plus/minus buttons on the shift lever to select the
desired range of gears for
current driving conditions.
When the shift lever is moved from
D (Drive) to M (Manual Mode), a
number displays next to the M,
indicating the current transmission
range.
This number is the highest gear that
the transmission will command while
operating in M (Manual Mode). All
gears below that number are
available. As driving conditions
change, the transmission can
automatically shift to lower gears.
For example, when 5 (Fifth) is
selected, 1 (First) through 5 (Fifth)
gears are automatically shifted by
the transmission, but 6 (Sixth)