2020 GMC SIERRA Owner's Manual

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
360 Vehicle Care
1. Loosen and remove thenegative battery cable nut (1)
at the battery sensor
connection.
2. Remove the negative battery cable (2) from the battery
sensor stud.
3. Cover the negative battery cable terminal, battery sensor
stud, and negative battery post
with a non-conductive material
to prevent any contact with the
negative battery cable.
For vehicles not equipped with the
Stop/Start system:1. Loosen the negative battery cable nut (1).
2. Remove the negative battery cable clamp (2) from the
negative battery post.
3. Cover the negative battery cable clamp, and negative
battery post with a
non-conductive material to
prevent any contact with the
negative battery cable.
Negative Battery Cable
Reconnection
Caution
When reconnecting the battery:. Use the original nut from the
vehicle to secure the
negative battery cable. Do
not use a different nut.
If you need a replacement
nut, see your dealer.
. Tighten the nut with a hand
tool. Do not use an impact
wrench or power tools to
tighten the nut.
The vehicle could be damaged if
these guidelines are not followed.
Caution
Do not use paints, lubricants,
or corrosion inhibitors on the nut
that secures the negative battery
cable to the vehicle. This could
damage the vehicle.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Vehicle Care 361
For vehicles equipped with the Stop/
Start system:1. Install the negative battery cable to the battery
sensor stud.
2. Install the negative battery cable nut to the battery sensor
stud and tighten.
3. Turn the ignition on.
For vehicles not equipped with the
Stop/Start system: 1. Install the negative battery cable clamp to the negative
battery post.
2. Tighten the negative battery cable nut.
3. Turn the ignition on.
Four-Wheel Drive
Transfer Case
When to Check Lubricant
Refer to Maintenance Schedule
0 442 to determine when to check
the lubricant.
1. Fill Plug
2. Drain Plug
To get an accurate reading, the
vehicle should be on a level
surface.
If the level is below the bottom of
the fill plug (1) hole, located on the
transfer case, some lubricant will
need to be added. Add enough
lubricant to raise the level to the
bottom of the fill plug (1) hole. Use
care not to overtighten the plug. When to Change Lubricant
Refer to
Maintenance Schedule
0 442 to determine how often to
change the lubricant.
What to Use
Refer to Recommended Fluids and
Lubricants 0453 to determine what
kind of lubricant to use.
Front Axle
When to Check Lubricant
It is not necessary to regularly
check the front axle fluid unless a
leak is suspected or an unusual
noise is heard. A fluid loss could
indicate a problem. Have it
inspected and repaired. This service
can be complex. See your dealer.
Do not directly power wash the
transfer case and/or front/rear axle
output seals. High pressure water
can overcome the seals and
contaminate the fluid. Contaminated
fluid will decrease the life of the
transfer case and/or drive axles and
should be replaced.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
362 Vehicle Care
Rear Axle
When to Check Lubricant
It is not necessary to regularly
check the rear axle fluid unless a
leak is suspected or an unusual
noise is heard. A fluid loss could
indicate a problem. Have it
inspected and repaired. This service
can be complex. See your dealer.
Do not directly power wash the
transfer case and/or front/rear axle
output seals. High pressure water
can overcome the seals and
contaminate the fluid. Contaminated
fluid will decrease the life of the
transfer case and/or drive axles and
should be replaced.
Noise Control System
NOISE EMISSIONS
WARRANTY
General Motors LLC, warrants to the
first person who purchases this
vehicle for purposes other than
resale and to each subsequent
purchaser that this vehicle as
manufactured by General MotorsLLC, was designed, built and
equipped to conform at the time it
left General Motors LLC’s control
with all applicable U.S. EPA Noise
Control Regulations. This warranty
covers this vehicle as designed,
built and equipped by General
Motors LLC, and is not limited to
any particular part, component or
system of the vehicle manufactured
by General Motors LLC. Defects in
design, assembly or in any part,
component or system of the vehicle
as manufactured by General Motors
LLC, which, at the time it left
General Motors LLC’
s control,
caused noise emissions to exceed
Federal standards, are covered by
this warranty for the life of the
vehicle.
TAMPERING WITH NOISE
CONTROL SYSTEM
PROHIBITED
Federal law prohibits the following
acts or the causing thereof:
1. The removal or rendering inoperative by any person,
other than for purposes of maintenance, repair,
or replacement, of any device
or element of design
incorporated into any new
vehicle for the purpose of noise
control prior to its sale or
delivery to the ultimate
purchaser or while it is in
use; or
2. the use of the vehicle after such device or element of
design has been removed or
rendered inoperative by any
person.
Among those acts presumed to
constitute tampering are the acts
listed below.
Insulation:
Removal of the noise shields or any
undercab insulation.
Engine:
Removal or rendering engine speed
governor, if so equipped, inoperative
so as to allow engine speed to
exceed manufacturer specifications.
Modification of the engine control
system or calibration.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Vehicle Care 363
Fan and Drive:
.Removal of fan clutch or
rendering clutch inoperative.
. Removal of the fan shroud.
Air Intake:
. Removal of air cleaner silencer.
. Reversing air cleaner cover.
Exhaust:
. Removal of muffler, catalytic
converter, and/or resonator.
. Removal of exhaust pipes and
exhaust pipe clamps.
Starter Switch Check
{Warning
When you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured. 1. Before starting this check, be
sure there is enough room
around the vehicle.
2. Apply both the parking brake and the regular brake.
Do not use the accelerator
pedal, and be ready to turn off
the engine immediately if it
starts.
3. Try to start the engine in each gear. The vehicle should start
only in P (Park) or N (Neutral).
If the vehicle starts in any other
position, contact your dealer for
service.
Automatic Transmission
Shift Lock Control
Function Check
{Warning
When you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured. 1. Before starting this check, be
sure there is enough room
around the vehicle. It should be
parked on a level surface.
2. Apply the parking brake. Be ready to apply the regular
brake immediately if the vehicle
begins to move.
3. With the engine off, turn the ignition on, but do not start the
engine. Without applying the
regular brake, try to move the
shift lever out of P (Park) with
normal effort. If the shift lever
moves out of P (Park), contact
your dealer for service.
Ignition Transmission
Lock Check
If equipped with Key Access
ignition, while parked, and with the
parking brake set, try to turn the
ignition off in each shift lever
position. The ignition should turn to
off only when the shift lever is in
P (Park).

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
364 Vehicle Care
The ignition key should come out
only when the ignition is off. Contact
your dealer if service is required.
Park Brake and P (Park)
Mechanism Check
{Warning
When you are doing this check,
the vehicle could begin to move.
You or others could be injured
and property could be damaged.
Make sure there is room in front
of the vehicle in case it begins to
roll. Be ready to apply the regular
brake at once should the vehicle
begin to move.
Park on a fairly steep hill, with the
vehicle facing downhill. Keeping
your foot on the regular brake, set
the parking brake.
. To check the parking brake's
holding ability: With the engine
running and the transmission in
N (Neutral), slowly remove foot pressure from the regular brake
pedal. Do this until the vehicle is
held by the parking brake only.
. To check the P (Park)
mechanism's holding ability:
With the engine running, shift to
P (Park). Then release the
parking brake followed by the
regular brake.
Contact your dealer if service is
required.
Wiper Blade Replacement
Windshield wiper blades should be
replaced periodically. See
Maintenance Schedule 0442.
Replacement blades come in
different types and are removed in
different ways. For proper type and
length, see Maintenance
Replacement Parts 0455.
Caution
Allowing the wiper arm to touch
the windshield when no wiper
blade is installed could damage
the windshield. Any damage that
occurs would not be covered by
the vehicle warranty. Do not allow
the wiper arm to touch the
windshield.
Front Wiper Blade
Replacement
To replace the wiper blade:
1. Pull the wiper assembly away from the windshield.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Vehicle Care 365
2. Lift up on the latch in themiddle of the wiper blade
where the wiper arm attaches.
3. With the latch open, pull the wiper blade down toward the
windshield far enough to
release it from the J-hooked
end of the wiper arm.
4. Remove the wiper blade.
5. Reverse Steps 1–3 for wiper blade replacement.
Windshield Replacement
HUD System
The windshield is part of the HUD
system. If the windshield must be
replaced, get one that is designed
for HUD or the HUD image may
look out of focus.
Driver Assistance Systems
If the windshield needs to be
replaced and the vehicle is
equipped with a front camera sensor
for the Driver Assistance Systems, a
GM replacement windshield is
recommended. The replacement
windshield must be installed
according to GM specifications for
proper alignment. If it is not, these
systems may not work properly, they
may display messages, or they may
not work at all. See your dealer for
proper windshield replacement.
Gas Strut(s)
This vehicle is equipped with gas
strut(s) to provide assistance in
lifting and holding open the hood/
trunk/liftgate system in full open
position.
{Warning
If the gas struts that hold open
the hood, trunk, and/or liftgate fail,
you or others could be seriously
injured. Take the vehicle to your
dealer for service immediately.
Visually inspect the gas struts for
signs of wear, cracks, or other
damage periodically. Check to
make sure the hood/trunk/liftgate
is held open with enough force.
If struts are failing to hold the
hood/trunk/liftgate, do not
operate. Have the vehicle
serviced.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
366 Vehicle Care
Caution
Do not apply tape or hang any
objects from gas struts. Also do
not push down or pull on gas
struts. This may cause damage to
the vehicle.
See Maintenance Schedule 0442.
Hood
Trunk
Liftgate
Headlamp Aiming
Headlamp aim has been preset and
should need no further adjustment.
If the vehicle is damaged in a crash,
the headlamp aim may be affected.
If adjustment to the headlamps is
necessary, see your dealer.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Vehicle Care 367
Bulb Replacement
For the proper type of replacement
bulbs, or any bulb changing
procedure not listed in this section,
contact your dealer.
Caution
Do not replace incandescent
bulbs with aftermarket LED
replacement bulbs. This can
cause damage to the vehicle
electrical system.
Halogen Bulbs
{Warning
Halogen bulbs have pressurized
gas inside and can burst if you
drop or scratch the bulb. You or
others could be injured. Be sure
to read and follow the instructions
on the bulb package.
LED Lighting
This vehicle has several LED lamps.
For replacement of any LED lighting
assembly, contact your dealer.
Headlamps, Front Turn
Signal, Sidemarker, and
Parking Lamps
Base Level Headlamp
Assembly
1. Turn Signal Lamps
Headlamp Replacement
See your dealer for headlamp
replacement.
Turn Signal Lamp
Replacement
Base Level1. Open the hood.
2. Turn the bulb socket counterclockwise to remove it
from the headlamp assembly
and pull it straight out.
3. Remove the bulb by pulling it straight out of the bulb socket.
4. Replace the bulb and reverse Steps 1–3 to reinstall.
Uplevel
See your dealer for headlamp
replacement.