
GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
Vehicle Care 373
8. Release the parking brake only when youare confident it is secured to tow vehicle
and will not roll.
Before going on to the next step, be
sure to take the mechanical key with
you. It will be needed to re-enter the
vehicle after the power is disconnected.
See “Drive Door Key Lock Cylinder
Access” underDoor Locks 015.
9. Disconnect the negative battery cable at the battery and secure the nut and bolt.
Cover the negative battery post with a
non-conductive material to prevent any
contact with the negative battery
terminal.
Caution
Failure to disconnect the negative battery
cable or to have it contact the terminals
can cause damage to the vehicle.
10. Move the steering wheel to make sure the steering column is unlocked.
Caution
If the steering column is locked, vehicle
damage may occur. 11. Rock the vehicle to make sure the
parking brake is not set and transfer case
is in N (Neutral).
Caution
Towing the vehicle with the parking
brake set can damage it. Always release
the parking brake prior to towing the
vehicle.
Disconnecting the Towed Vehicle
Before disconnecting the towed vehicle: 1. Park on a level surface.
2. Connect the battery.
3. Apply the brake pedal.
{Warning
The vehicle can roll when the brake pedal
is released. Always apply and hold the
brake pedal when setting the parking
brake. Make sure the parking brake is
fully engaged before releasing the brake
pedal.
4. Start the engine and shift the transfer case out of N (Neutral) to 2
m. See “Shifting out of N (Neutral)”
under
Four-Wheel Drive 0236. See your dealer
if the transfer case cannot be shifted out
of N (Neutral).
5. Check that the vehicle is in 2
mby
shifting the transmission to R (Reverse)
and then to D (Drive). There should be
movement of the vehicle while shifting.
6. Shift the transmission to P (Park) and turn off the vehicle.
7. Set the parking brake.
8. Release the parking brake.
9. Disconnect the vehicle from the tow vehicle.
10. Reset any lost presets. The outside temperature display will
default to 0 °C (32 °F) but will reset with
normal usage.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-13690468) - 2021 - crc - 8/14/20
OnStar 411
.Receive a Diagnostic check of the vehicle's
key operating systems.
.Receive Roadside Assistance.
.Manage Wi-Fi Settings, if equipped.
Press
>to get a priority connection to an
OnStar Advisor available 24/7 to:
.Get help for an emergency.
.Be a Good Samaritan or respond to an
AMBER Alert.
.Get assistance in severe weather or other
crisis situations and find evacuation
routes.
OnStar Services
Emergency
Emergency Services require an active safety
and security plan. With Automatic Crash
Response, built-in sensors can automatically
alert a specially trained OnStar Advisor who
is immediately connected in to the vehicle
to help.
Press
>for a priority connection to an
OnStar Advisor who can contact emergency
service providers, direct them to your exact
location, and relay important information. With OnStar Crisis Assist, specially trained
Advisors are available 24 hours a day, 7 days
a week, to provide a central point of
contact, assistance, and information during a
crisis.
With Roadside Assistance, Advisors can
locate a nearby service provider to help with
a flat tire, a battery jump, or an empty
gas tank.
Security
If equipped, OnStar provides these services:
.With Stolen Vehicle Assistance, OnStar
Advisors can use GPS to pinpoint the
vehicle and help authorities quickly
recover it.
.With Remote Ignition Block, if equipped,
OnStar can block the engine from being
restarted.
.With Stolen Vehicle Slowdown,
if equipped, OnStar can work with law
enforcement to gradually slow the
vehicle down.
Theft Alarm Notification
If equipped, if the doors are locked and the
vehicle alarm sounds, a notification by text,
e-mail, or phone call will be sent. If the
vehicle is stolen, an OnStar Advisor can work
with authorities to recover the vehicle.
OnStar Additional
Information
In-Vehicle Audio Messages
Audio messages may play important
information at the following times:
.Prior to vehicle purchase. PressQto set
up an account.
.After change in ownership and at
90 days.
Transferring Service
PressQto request account transfer
eligibility information. The Advisor can
cancel or change account information.
Selling/Transferring the Vehicle
Call 1-888-4ONSTAR (1-888-466-7827)
immediately to terminate your OnStar or
connected services if the vehicle is disposed
of, sold, transferred, or if the lease ends.

GMC Yukon/Yukon XL/Denali Owner Manual (GMNA-Localizing-U.S./Cana-
da/Mexico-13690468) - 2021 - crc - 8/14/20
Index 423
HVAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204, 207
I
If the System Needs Service . . . . . . . . . . . . . . 175
Ignition Positions . . . . . . . . . . . . . . . . . . . . . . . . 226
Immobilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
IndicatorPedestrian Ahead . . . . . . . . . . . . . . . . . . . . . . . 115
Vehicle Ahead . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Infants and Young Children, Restraints . . . . .72
Information Publication Ordering . . . . . . . . . . . . . . . . . . . 406
Infotainment System . . . . . . . . . . . . . . . . . . . . 409 Rear Seat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Instrument Cluster . . . . . . . . . . . . . . . . . . . . . . . 104
Instrument Panel Storage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Instrument Panel Overview . . . . . . . . . . . . . . . . 4
Interior Rearview Mirrors . . . . . . . . . . . . . . . . . 30
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 142
J
Jump Starting - North America . . . . . . . . . . . 367
K
Keyless Entry Remote (RKE) System . . . . . . . . . . . . . . . . . . . . 8
Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
L
Labeling, Tire Sidewall . . . . . . . . . . . . . . . . . . . .341
Lamps
Daytime Running (DRL) . . . . . . . . . . . . . . . . 136
Dome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Exterior Controls . . . . . . . . . . . . . . . . . . . . . . . 134
Exterior Lamps Off Reminder . . . . . . . . . . 136
Exterior Lighting Battery Saver . . . . . . . . . 141
Malfunction Indicator (CheckEngine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
On Reminder . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Lane Change Alert (LCA) . . . . . . . . . . . . . . . . . 272
Lane Keep Assist (LKA) . . . . . . . . . . . . . . . . . . . 275
Lane Keep Assist Light . . . . . . . . . . . . . . . . . . . . 114
Lap-Shoulder Belt . . . . . . . . . . . . . . . . . . . . . . . . . 56
LATCH System Replacing Parts after a Crash . . . . . . . . . . . 83
LATCH, Lower Anchors and Tethers for
Children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77
LED Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Liftgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Lighting Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Exit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Illumination Control . . . . . . . . . . . . . . . . . . . 139
LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 Lights
Airbag Readiness . . . . . . . . . . . . . . . . . . . . . . 109
Antilock Brake System (ABS)
Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Brake System Warning . . . . . . . . . . . . . . . . . 112
Charging System . . . . . . . . . . . . . . . . . . . . . . . 111
Check Engine (Malfunction Indicator) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Cruise Control . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Door Ajar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Driver Mode Control . . . . . . . . . . . . . . . . . . . . 116
Electric Parking Brake . . . . . . . . . . . . . . . . . . . 113
Electronic Stability Control (ESC), Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Engine Coolant Temperature Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Engine Oil Pressure . . . . . . . . . . . . . . . . . . . . . 118
Flash-to-Pass . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Four Corner Air Suspension . . . . . . . . . . . . . 117
Four-Wheel-Drive . . . . . . . . . . . . . . . . . . . . . . . 114
Front Fog Lamp . . . . . . . . . . . . . . . . . . . . . . . . . 119
High-Beam On . . . . . . . . . . . . . . . . . . . . . . . . . . 119
High/Low Beam Changer . . . . . . . . . . . . . . 136
Hill Descent Control . . . . . . . . . . . . . . . . . . . . 114
Lane Keep Assist . . . . . . . . . . . . . . . . . . . . . . . . 114
Low Fuel Warning . . . . . . . . . . . . . . . . . . . . . . 118
Seat Belt Reminders . . . . . . . . . . . . . . . . . . . 109
Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119