
Black plate (24,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
10-24 Vehicle Care
distances and/or towing a trailer in
the overheat protection mode
should be avoided.
{Caution
After driving in the overheated
engine protection operating
mode, the engine oil will be
severely degraded. Any repairs
performed before the engine is
cool may cause engine damage.
Allow the engine to cool before
attempting any repair. Repair the
cause of coolant loss, change the
oil, and reset the oil life system.
SeeEngine Oil on page 10-8.
Engine Fan
If the vehicle has a clutched engine
cooling fan, when the clutch is
engaged, the fan spins faster to
provide more air to cool the engine.
In most everyday driving conditions,
the fan is spinning slower and the
clutch is not fully engaged. This
improves fuel economy and reduces fan noise. Under heavy vehicle
loading, trailer towing, and/or high
outside temperatures, the fan speed
increases as the clutch more fully
engages, so an increase in fan
noise may be heard. This is normal
and should not be mistaken as the
transmission slipping or making
extra shifts. It is merely the cooling
system functioning properly. The fan
will slow down when additional
cooling is not required and the
clutch disengages.
This fan noise may also be heard
when starting the engine. It will go
away as the fan clutch partially
disengages.
If the vehicle has electric cooling
fans, the fans may be heard
spinning at low speed during most
everyday driving. The fans may turn
off if no cooling is required. Under
heavy vehicle loading, trailer towing,
high outside temperatures,
or operation of the air conditioning
system, the fans may change to
high speed and an increase in fan
noise may be heard. This is normaland indicates that the cooling
system is functioning properly. The
fans will change to low speed when
additional cooling is no longer
required.
The electric engine cooling fans
may run after the engine has been
turned. off. This is normal and no
service is required.
Power Steering Fluid
(1500 Series)
The vehicle has electric power
steering and does not use power
steering fluid.
Power Steering Fluid
(2500/3500 Series)

Black plate (101,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
Vehicle Care 10-101
2500/3500 Series vehicles, at least
every other engine oil change
lubricate the upper and lower
control arm ball joints. Control arm
ball joints on 1500 series vehicles
are maintenance-free.
2500/3500 Series vehicles equipped
with steering linkage, at least every
other engine oil change lubricate the
tie rod ball joints, idler arm pivot
shaft bearings, idler arm socket, and
pitman arm socket.
{Caution
Lubrication of applicable Steering/
Suspension points should not be
done unless temperature is -12°C
(10°F) or higher, or damage could
result.
Body Component Lubrication
Lubricate all key lock cylinders,
hood hinges, liftgate hinges, and the
steel fuel door hinge unless the
components are plastic. Applying
silicone grease on weatherstripswith a clean cloth will make them
last longer, seal better, and not stick
or squeak.
Underbody Maintenance
At least twice a year, spring and fall,
use plain water to flush dirt and
debris from the vehicle's underbody.
Your dealer or an underbody car
washing system can do this. If not
removed, rust and corrosion can
develop.
Sheet Metal Damage
If the vehicle is damaged and
requires sheet metal repair or
replacement, make sure the body
repair shop applies anti-corrosion
material to parts repaired or
replaced to restore corrosion
protection.
Original manufacturer replacement
parts will provide the corrosion
protection while maintaining the
vehicle warranty.
Finish Damage
Quickly repair minor chips and
scratches with touch-up materials
available from your dealer to avoid
corrosion. Larger areas of finish
damage can be corrected in your
dealer's body and paint shop.
Chemical Paint Spotting
Airborne pollutants can fall upon
and attack painted vehicle surfaces
causing blotchy, ring-shaped
discolorations, and small, irregular
dark spots etched into the paint
surface. Refer to
“Finish Care”
previously in this section.
Interior Care
To prevent dirt particle abrasions,
regularly clean the vehicle's interior.
Immediately remove any soils. Note
that newspapers or dark garments
that can transfer color to home
furnishings can also permanently
transfer color to the vehicle's
interior.

Black plate (4,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
i-4 INDEX
Driving (cont'd)Drunk . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
For Better Fuel Economy . . . . . 1-21
Hill and Mountain Roads . . . . . . 9-11
If the Vehicle is Stuck . . . . . . . . . 9-14
Loss of Control . . . . . . . . . . . . . . . . 9-5
Off-Road . . . . . . . . . . . . . . . . . . . . . . 9-6
Off-Road Recovery . . . . . . . . . . . . 9-5
Vehicle Load Limits . . . . . . . . . . . 9-15
Wet Roads . . . . . . . . . . . . . . . . . . . 9-11
Winter . . . . . . . . . . . . . . . . . . . . . . . . 9-12
Dual Automatic Climate Control System . . . . . . . . . . . . . . . . 8-1
Dual Tire
Rotation . . . . . . . . . . . . . . . . . . . . 10-67
E
E85 or FlexFuel . . . . . . . . . . . . . . . 9-65
Electrical Equipment,Add-On . . . . . . . . . . . . . . . . . . . . . . 9-88
Electrical System Engine CompartmentFuse Block . . . . . . . . . . . . . . . . 10-41
Fuses . . . . . . . . . . . . . . . . . . . . . . 10-41 Electrical System (cont'd)
Instrument Panel
Fuse Block . . . . . . . . . 10-45, 10-48
Overload . . . . . . . . . . . . . . . . . . . 10-40
Emergency OnStar
®. . . . . . . . . . . . . . . . . . . . . . 14-2
Engine Air Cleaner/Filter . . . . . . . . . . . 10-15
Check and Service EngineSoon Light . . . . . . . . . . . . . . . . . . 5-18
Compartment Overview . . . . . . . 10-5
Coolant . . . . . . . . . . . . . . . . . . . . . 10-18
Coolant Temperature Gauge . . . . . . . . . . . . . . . . . . . . . . 5-13
Coolant Temperature Warning Light . . . . . . . . . . . . . . . 5-24
Cooling System . . . . . . . . . . . . . 10-17
Cooling System Messages . . . 5-33
Drive Belt Routing . . . . . . . . . . . . 12-4
Exhaust . . . . . . . . . . . . . . . . . . . . . . 9-32
Fan . . . . . . . . . . . . . . . . . . . . . . . . . 10-24
Heater . . . . . . . . . . . . . . . . . . . . . . . . 9-28
Oil Life System . . . . . . . . . . . . . .10-11
Oil Messages . . . . . . . . . . . . . . . . . 5-34
Oil Pressure Gauge . . . . . . . . . . 5-12
Overheated Protection Operating Mode . . . . . . . . . . . 10-23 Engine (cont'd)
Overheating . . . . . . . . . . . . . . . . 10-21
Power Messages . . . . . . . . . . . . . 5-34
Pressure Light . . . . . . . . . . . . . . . . 5-25
Running While Parked . . . . . . . . 9-33
Starting . . . . . . . . . . . . . . . . . . . . . . . 9-26
Entry Lighting . . . . . . . . . . . . . . . . . . . 6-8
Equipment, Towing . . . . . . . . . . . . 9-78
Event Data Recorders . . . . . . . . 13-14
Exit Lighting . . . . . . . . . . . . . . . . . . . . 6-8
Extender, Safety Belt . . . . . . . . . . 3-15
Exterior Lamp Controls . . . . . . . . . 6-1
Exterior Lamps Off Reminder . . . 6-2
F
Fan Engine . . . . . . . . . . . . . . . . . . . . . . 10-24
Fast Idle System . . . . . . . . . . . . . . . 9-27
Features Memory . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Filter, Engine Air Cleaner . . . . . . . . . 10-15
Flash-to-Pass . . . . . . . . . . . . . . . . . . . 6-2
Flashers, Hazard Warning . . . . . . 6-4
Flat Tire . . . . . . . . . . . . . . . . . . . . . . 10-74 Changing . . . . . . . . . . . . . . . . . . . 10-76

Black plate (5,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
INDEX i-5
FlexFuelE85 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-65
Floor Console Storage . . . . . . . . . . 4-3
Floor Mats . . . . . . . . . . . . . . . . . . .10-105
Fluid AutomaticTransmission . . . . . . . 10-12, 10-15
Brakes . . . . . . . . . . . . . . . . . . . . . . 10-27
Four-Wheel Drive Transfer Case . . . . . . . . . . . . . . . 9-40
Power Steering . . . . . . . . . . . . . 10-24
Washer . . . . . . . . . . . . . . . . . . . . . 10-25
Fog Lamps . . . . . . . . . . . . . . . . . . . . . 6-5 Bulb Replacement . . . . . . . . . . 10-37
Folding Mirrors . . . . . . . . . . . . . . . . 2-16
Forward Collision Alert (FCA) System . . . . . . . . . . . . . . . . 9-59
Four-Wheel Drive . . . . . . . 9-40, 10-29
Four-Wheel-Drive Light . . . . . . . . 5-22
Frequency Statement Radio . . . . . . . . . . . . . . . . . . . . . . . 13-12
Front Axle . . . . . . . . . . . . . . . . . . . . 10-30 Front Fog Lamp
Light . . . . . . . . . . . . . . . . . . . . . . . . . . 5-26
Front Seats Heated and Cooled . . . . . . . . . . . . 3-7
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-63 Additives . . . . . . . . . . . . . . . . . . . . . 9-64
Economy Driving . . . . . . . . . . . . . 1-21
Filling a Portable FuelContainer . . . . . . . . . . . . . . . . . . . 9-67
Filling the Tank . . . . . . . . . . . . . . . 9-66
Foreign Countries . . . . . . . . . . . . 9-64
Gauge . . . . . . . . . . . . . . . . . . . . . . . . 5-12
Low Fuel Warning Light . . . . . . . 5-25
Management, Active . . . . . . . . . . 9-32
Requirements, California . . . . . 9-64
System Messages . . . . . . . . . . . . 5-35
Full-Size Spare Tire . . . . . . . . . . 10-86
Fuses . . . . . . . . . . . . . . . . . . . . . . . . 10-41 Engine CompartmentFuse Block . . . . . . . . . . . . . . . . 10-41
Instrument Panel
Fuse Block . . . . . . . . . 10-45, 10-48G
Garage Door Opener . . . . . . . . . . 5-49Programming . . . . . . . . . . . . . . . . . 5-49
Gauges Engine CoolantTemperature . . . . . . . . . . . . . . . . 5-13
Engine Oil Pressure . . . . . . . . . . 5-12
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12
Odometer . . . . . . . . . . . . . . . . . . . . . 5-11
Speedometer . . . . . . . . . . . . . . . . . 5-11
Tachometer . . . . . . . . . . . . . . . . . . . 5-11
Transmission Temperature . . . . 5-14
Trip Odometer . . . . . . . . . . . . . . . . 5-11
Voltmeter . . . . . . . . . . . . . . . . . . . . . 5-15
Warning Lights and Indicators . . . . . . . . . . . . . . . . . . . . 5-8
General Information Service and Maintenance . . . . . 11-1
Towing . . . . . . . . . . . . . . . . . . . . . . . . 9-68
Vehicle Care . . . . . . . . . . . . . . . . . . 10-2
Glass Replacement . . . . . . . . . . . 10-35
Glove Box . . . . . . . . . . . . . . . . . . . . . . 4-1
GM Mobility Reimbursement Program . . . . . . . . . . . . . . . . . . . . . . 13-5

Black plate (7,1)GMC 2015i Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-8431500) - 2015 - crc - 6/20/14
INDEX i-7
Lamps (cont'd)Messages . . . . . . . . . . . . . . . . . . . . 5-35
On Reminder . . . . . . . . . . . . . . . . . 5-26
Reading . . . . . . . . . . . . . . . . . . . . . . . 6-7
Lane Departure Warning (LDW) . . . . . . . . . . . . . . . 9-61
Lane Departure Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . 5-22
Lap-Shoulder Belt . . . . . . . . . . . . . 3-12
LATCH System
Replacing Parts after aCrash . . . . . . . . . . . . . . . . . . . . . . . 3-45
LATCH, Lower Anchors and Tethers for Children . . . . . . . . . . 3-38
LED Lighting . . . . . . . . . . . . . . . . . . 10-36
Light Hill Decent Control . . . . . . . . . . . 5-22
Lighting
Entry . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
Exit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
Illumination Control . . . . . . . . . . . . 6-6
LED . . . . . . . . . . . . . . . . . . . . . . . . 10-36
Lights
Airbag Readiness . . . . . . . . . . . . . 5-16
Antilock Brake System(ABS) Warning . . . . . . . . . . . . . . 5-21
Brake System Warning . . . . . . . 5-21 Lights (cont'd)
Charging System . . . . . . . . . . . . . 5-18
Cruise Control . . . . . . . . . . . . . . . . 5-27
Door Ajar . . . . . . . . . . . . . . . . . . . . . 5-27
Engine Coolant
Temperature Warning . . . . . . . 5-24
Engine Oil Pressure . . . . . . . . . . 5-25
Flash-to-Pass . . . . . . . . . . . . . . . . . . 6-2
Four-Wheel-Drive . . . . . . . . . . . . . 5-22
Front Fog Lamp . . . . . . . . . . . . . . 5-26
High-Beam On . . . . . . . . . . . . . . . . 5-26
High/Low Beam Changer . . . . . . 6-2
Lane Departure Warning . . . . . . 5-22
Low Fuel Warning . . . . . . . . . . . . 5-25
Safety Belt Reminders . . . . . . . . 5-15
Security . . . . . . . . . . . . . . . . . . . . . . 5-26
StabiliTrak
®OFF . . . . . . . . . . . . . 5-23
Tire Pressure . . . . . . . . . . . . . . . . . 5-25
Tow/Haul Mode . . . . . . . . . . . . . . . 5-22
Traction Control System
(TCS)/StabiliTrak
®. . . . . . . . . . 5-24
Traction Off . . . . . . . . . . . . . . . . . . . 5-23
Locking Rear Axle . . . . . . . . . . . . . 9-52
Locks
Automatic Door . . . . . . . . . . . . . . . . 2-9
Delayed Locking . . . . . . . . . . . . . . . 2-9
Door . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8 Locks (cont'd)
Lockout Protection . . . . . . . . . . . . . 2-9
Power Door . . . . . . . . . . . . . . . . . . . . 2-9
Safety . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Loss of Control . . . . . . . . . . . . . . . . . 9-5
Low Fuel Warning Light . . . . . . . . 5-25
Low-Profile Tires . . . . . . . . . . . . . . 10-51
Lower Anchors and Tethers for Children (LATCH
System) . . . . . . . . . . . . . . . . . . . . . . 3-38
Lumbar Adjustment . . . . . . . . . . . . . 3-3 Front Seats . . . . . . . . . . . . . . . . . . . . 3-3
M
MaintenanceRecords . . . . . . . . . . . . . . . . . . . . .11-16
Maintenance and Care Additional . . . . . . . . . . . . . . . . . . . . . 11-9
Maintenance Schedule . . . . . . . . 11-3 Recommended Fluids
and Lubricants . . . . . . . . . . . . .11-12
Transfer Case . . . . . . . . . . . . . . . . 9-40
Malfunction Indicator Lamp . . . . 5-18
Manual Mode . . . . . . . . . . . . . . . . . . 9-36
Memory Features . . . . . . . . . . . . . . . 1-8
Memory Seats . . . . . . . . . . . . . . . . . . 3-5