
Black plate (24,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
9-24 Driving and Operating
The 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 place the
ignition system in ON/RUN/START.
Once engine cranking begins,
release the button. Engine cranking
will continue until the engine starts.
See Starting the Engine on
page 9-24. The ignition will then
remain in ON/RUN.
Service Only 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 Only Mode. The instruments and audio systems
will operate as they do in ON/RUN,
but the vehicle will not be able to be
driven. The engine will not start in
Service Only Mode. Press the
button again to turn the vehicle off.
Starting the Engine
Move the shift lever to P (Park) or
N (Neutral). The engine will not start
in any other position. To restart the
engine when the vehicle is already
moving, use N (Neutral) only.
{Caution
Do not try to shift to P (Park) if the
vehicle is moving. If you do, you
could damage the transmission.
Shift to P (Park) only when the
vehicle is stopped.
{Caution
If you add electrical parts or
accessories, you could change
the way the engine operates. Any
resulting damage would not be
covered by the vehicle warranty.
See
Add-On Electrical Equipment
on page 9-89.
Starting Procedure (Key
Access)
1. With your foot off the accelerator pedal, turn the ignition key to
START. When the engine starts,
let go of the key. The idle speed
will go down as the engine gets
warm. Do not race the engine
immediately after starting it.
Operate the engine and
transmission gently to allow the
oil to warm up and lubricate all
moving parts.
When the low fuel warning lamp
is on and the FUEL LEVEL LOW
message is displayed in the

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 (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 (83,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Driving and Operating 9-83
Since the vehicle is equipped with
StabiliTrak, the trailer brakes cannot
tap into the vehicle's hydraulic
system.
Trailer Wiring Harness
The seven-pin trailer connector is
mounted in the bumper. This
connector can be plugged into a
seven-pin universal heavy-duty
trailer connector available through
your dealer.
The seven-wire harness contains
the following trailer circuits:
.Yellow: Left Stop/Turn Signal
.Green/Violet: Right Stop/Turn
Signal
.Brown: Taillamps
.White: Ground
.Light Green: Back-up Lamps
.Red/Green: Battery Feed
.Dark Blue: Trailer Brake
If charging a remote (non-vehicle)
battery, press the Tow/Haul mode
button at the end of the shift lever. This will boost the vehicle system
voltage and properly charge the
battery. If the trailer is too light for
Tow/Haul mode, turn on the
headlamps as a second way to
boost the vehicle system and
charge the battery.
Electric Brake Control Wiring
Provisions
These wiring provisions are
included with the vehicle as part of
the trailer wiring package. These
provisions are for an electric brake
controller.
The harness should be installed by
your dealer or a qualified service
center.
Tow/Haul Mode
Pressing this button at the end of
the shift lever turns on and off the
Tow/Haul Mode.
This indicator light on the instrument
cluster comes on when the Tow/
Haul Mode is on.

Black plate (89,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Driving and Operating 9-89
{Warning
Even if the vehicle is equipped
with TSC, trailer sway could result
in loss of control and the vehicle
could crash. If excessive trailer
sway is detected, slow down to a
safe speed. Check the trailer and
vehicle to help correct possible
causes. These could include an
improperly or overloaded trailer,
unrestrained cargo, improper
trailer hitch configuration,
excessive vehicle-trailer speed,
or improperly inflated or incorrect
vehicle or trailer tires. SeeTowing
Equipment on page 9-82 for
trailer ratings and hitch setup
recommendations.
Adding non-dealer accessories can
affect the vehicle performance. See
Accessories and Modifications on
page 10-3.
Conversions and
Add-Ons
Add-On Electrical
Equipment
{Caution
Some electrical equipment can
damage the vehicle or cause
components to not work and
would not be covered by the
warranty. Always check with your
dealer before adding electrical
equipment.
Add-on equipment can drain the
vehicle's 12-volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle on page 3-40 andAdding
Equipment to the Airbag-Equipped
Vehicle on page 3-40.

Black plate (1,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
Vehicle Care 10-1
Vehicle Care
General Information
General Information . . . . . . . . . . 10-2
California Proposition65 Warning . . . . . . . . . . . . . . . . . 10-2
California Perchlorate Materials Requirements . . . . 10-3
Accessories and Modifications . . . . . . . . . . . . . . . 10-3
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 10-3
Hood . . . . . . . . . . . . . . . . . . . . . . . . 10-4
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . 10-5
Engine Oil . . . . . . . . . . . . . . . . . . . 10-6
Engine Oil Life System . . . . . . 10-9
Automatic Transmission Fluid . . . . . . . . . . . . . . . . . . . . . . 10-10
Engine Air Cleaner/Filter . . . . 10-13
Cooling System . . . . . . . . . . . . 10-14
Engine Coolant . . . . . . . . . . . . . 10-15
Engine Overheating . . . . . . . . 10-18
Engine Fan . . . . . . . . . . . . . . . . . 10-19
Washer Fluid . . . . . . . . . . . . . . . 10-20
Brakes . . . . . . . . . . . . . . . . . . . . . 10-20 Brake Fluid . . . . . . . . . . . . . . . . . 10-21
Battery . . . . . . . . . . . . . . . . . . . . . 10-23
Four-Wheel Drive . . . . . . . . . . . 10-24
Front Axle . . . . . . . . . . . . . . . . . . 10-24
Rear Axle . . . . . . . . . . . . . . . . . . 10-25
Noise Control System . . . . . . 10-26
Starter Switch Check . . . . . . . 10-27
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . 10-27
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . 10-27
Park Brake and P (Park) Mechanism Check . . . . . . . . 10-28
Wiper Blade Replacement . . . . . . . . . . . . . . 10-28
Glass Replacement . . . . . . . . 10-29
Windshield Replacement . . . 10-29
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . 10-29
Bulb Replacement
Bulb Replacement . . . . . . . . . . 10-30
High Intensity Discharge (HID) Lighting . . . . . . . . . . . . . 10-30
LED Lighting . . . . . . . . . . . . . . . 10-30
Headlamps . . . . . . . . . . . . . . . . . 10-30
Front Turn Signal Lamps . . . 10-30 Taillamps, Turn Signal,
Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . 10-31
License Plate Lamp . . . . . . . . 10-32
Replacement Bulbs . . . . . . . . . 10-33
Electrical System
Electrical System Overload . . . . . . . . . . . . . . . . . . 10-33
Fuses . . . . . . . . . . . . . . . . . . . . . . 10-33
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . 10-34
Instrument Panel Fuse Block (Left) . . . . . . . . . . . . . . . 10-38
Instrument Panel Fuse Block (Right) . . . . . . . . . . . . . . . . . . . . 10-40
Rear Compartment Fuse
Block . . . . . . . . . . . . . . . . . . . . . 10-43
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . 10-44
All-Season Tires . . . . . . . . . . . . 10-45
Winter Tires . . . . . . . . . . . . . . . . 10-45
Low-Profile Tires . . . . . . . . . . . 10-46
All-Terrain Tires . . . . . . . . . . . . 10-46
Tire Sidewall Labeling . . . . . . 10-46
Tire Designations . . . . . . . . . . . 10-48
Tire Terminology andDefinitions . . . . . . . . . . . . . . . . 10-49

Black plate (6,1)GMC 2015i Yukon/Yukon XL Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431503) - 2015 - crc - 8/11/14
10-6 Vehicle Care
1. Positive (+) Terminal. SeeJump
Starting on page 10-78.
2. Battery on page 10-23.
3. Coolant Surge Tank and Pressure Cap. See Cooling
System on page 10-14.
4. Engine Air Cleaner/Filter on
page 10-13.
5. Automatic Transmission Dipstick. See “How to Check
Automatic Transmission Fluid”
under Automatic Transmission
Fluid on page 10-10.
6. Remote Negative (–) Location (Out of View). See Jump Starting
on page 10-78.
7. Engine Cooling Fans (Out of View). See Cooling System on
page 10-14.
8. Engine Oil Fill Cap. See “When
to Add Engine Oil” underEngine
Oil on page 10-6.
9. Engine Oil Dipstick. See “Checking Engine Oil” under
Engine Oil on page 10-6. 10. Windshield Washer Fluid
Reservoir. See “Adding Washer
Fluid” under Washer Fluid on
page 10-20.
11. Brake Fluid Reservoir. See Brake Fluid on page 10-21.
12. Engine Compartment Fuse
Block on page 10-34.
Engine Oil
To ensure proper engine
performance and long life, careful
attention must be paid to engine oil.
Following these simple, but
important steps will help protect
your investment:
.Always use engine oil approved
to the proper specification and of
the proper viscosity grade. See
“Selecting the Right Engine Oil”
in this section.
.Check the engine oil level
regularly and maintain the
proper oil level. See “Checking
Engine Oil” and“When to Add
Engine Oil” in this section.
.Change the engine oil at the
appropriate time. See Engine Oil
Life System on page 10-9.
.Always dispose of engine oil
properly. See “What to Do with
Used Oil” in this section.
Checking Engine Oil
If equipped, the ENGINE OIL LOW
ADD OIL message displays when
the engine oil level may be too low.
SeeEngine Oil Messages on
page 5-34. Check the oil level
before filling to the recommended
level. If the oil is not low and this
message remains on, see your
dealer.
It is also a good idea to check the
engine oil level at each fuel fill. In
order to get an accurate reading,
the vehicle must be on level ground.
The engine oil dipstick handle is a
loop. See Engine Compartment
Overview on page 10-5 for the
location of the engine oil dipstick.