clock GMC SIERRA 2021 User Guide

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 337
Check to see if coolant is visible in the
coolant surge tank. If the coolant inside the
coolant surge tank is boiling, wait until it
cools down. The coolant level should be at
or above the indicated mark. If it is not,
there may be a leak in the cooling system.
If coolant is visible but the coolant level is
not at or above the indicated mark, see the
following sections on how to add coolant to
the coolant surge tank following.
Automatic Coolant Service Fill
Instructions (L3B Engine)
This feature assists in filling and removing
air from the cooling system after service of
components or when coolant is added after
being too low.
To activate the fill and air removal process:1. Remove the coolant surge tank pressure cap when the cooling system, including
the coolant surge tank pressure cap and
upper radiator hose, is no longer hot.
Turn the pressure cap; slowly
counterclockwise about one full turn. If a
hiss is heard, wait for that to stop.
A hiss means there is still some
pressure left. 2. Keep turning the pressure cap slowly,
and remove it.
3. Fill the coolant surge tank with the proper mixture to the indicated mark.
4. Connect the vehicle to a battery charger.
5. Set the ignition to service mode, see Ignition Positions (Keyless Access) 0230
or
Ignition Positions (Key Access) 0229.
6. Turn off the air conditioning.
7. Set the parking brake.
8. At the same time, press the accelerator and the brake for automatic vehicles for
two seconds, then release.
9. Listen for pump activation and movement of the control valves while
watching the level of the coolant in the
surge tank. Add fluid as the level drops
below the indicated mark on the surge
tank. Allow 15 minutes for the fill and air
removal process to complete.
10. Reinstall the surge tank cap.
If the tank empties, turn the ignition off,
allow the Electronic Control Module (ECM) to
go to sleep, about two minutes, refill to the
indicated mark, and repeat Steps 5–9.
How to Add Coolant to the Coolant
Surge Tank for Gasoline Engines
Except L3B
If the vehicle has a diesel engine, see
“Cooling System” in the Duramax diesel
supplement for the proper coolant fill
procedure.
{Warning
Spilling coolant on hot engine parts can
burn you. Coolant contains ethylene
glycol and it will burn if the engine parts
are hot enough.
{Warning
Plain water, or other liquids such as
alcohol, can boil before the proper
coolant mixture will. With plain water or
the wrong mixture, the engine could get
too hot but there would not be an
overheat warning. The engine could catch
fire and you or others could be burned.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
338 Vehicle Care
{Warning
Steam and scalding liquids from a hot
cooling system are under pressure.
Turning the pressure cap, even a little,
can cause them to come out at high
speed and you could be burned. Never
turn the cap when the cooling system,
including the pressure cap, is hot. Wait
for the cooling system and pressure cap
to cool.
Caution
Failure to follow the specific coolant fill
procedure could cause the engine to
overheat and could cause system
damage. If coolant is not visible in the
surge tank, contact your dealer.
If no coolant is visible in the surge tank, add
coolant.
1. Remove the coolant surge tank pressure cap when the cooling system, including
the coolant surge tank pressure cap and
upper radiator hose, is no longer hot.
Turn the pressure cap slowly
counterclockwise about one full turn. If a
hiss is heard, wait for that to stop.
A hiss means there is still some
pressure left.
2. Keep turning the pressure cap slowly, and remove it.
3. Fill the coolant surge tank with the proper mixture to the full cold mark.
4. With the coolant surge tank pressure cap off, start the engine and let it run until
the engine coolant temperature gauge
indicates approximately 90 °C (195 °F).
By this time, the coolant level inside the
coolant surge tank may be lower. If the
level is lower, add more of the proper
mixture to the coolant surge tank until
the level reaches the indicated mark.
5. Replace the pressure cap tightly.
6. Verify coolant level after the engine is shut off and the coolant is cold.
If necessary, repeat coolant fill procedure
Steps 1–6.Caution
If the pressure cap is not tightly installed,
coolant loss and engine damage may
occur. Be sure the cap is properly and
tightly secured.
Engine Overheating
If the vehicle has the Duramax diesel
engine, see the Duramax diesel supplement.
Caution
Do not run the engine if there is a leak
in the engine cooling system. This can
cause a loss of all coolant and can
damage the system and vehicle. Have
any leaks fixed right away.
The vehicle has several indicators to warn of
engine overheating.
There is a coolant temperature gauge in the
vehicle's instrument cluster. See Engine
Coolant Temperature Gauge 0112.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
350 Vehicle Care
Headlamp Aiming
Front 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.
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.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 351
3. Remove the bulb by pulling it straightout of the bulb socket.
4. Replace the bulb and reverse Steps 1–3 to reinstall.
Uplevel
See your dealer for headlamp replacement.
Taillamps, Turn Signal, Stoplamps,
and Back-Up Lamps
Base Level Taillamp Assembly
1. Stoplamp/Turn Signal Lamp
2. Back-Up Lamp
Uplevel Taillamp Assembly
See your dealer for taillamp replacement.
It is recommended to replace the grommets
when replacing a bulb. See your dealer.
To replace one of these bulbs: 1. Open the tailgate.
2. Remove the two rear lamp assembly screws.
4. Pull the rear lamp assembly outward andrearward away from the box side to
remove it from the vehicle.
5. Turn the bulb socket counterclockwise.
6. Pull the bulb straight out from the socket.
7. Replace the bulb and reverse Steps 1–5 to reinstall.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
352 Vehicle Care
Center High-Mounted Stoplamp
(CHMSL) and Cargo Lamp
This procedure is for the regular cab only.
For crew cab and double cab see your
dealer.
1. Cargo Lamp Bulbs
2. Center High-Mounted Stoplamp(CHMSL) Bulb
To replace one of these bulbs:
1. Remove the two screws and lift off thelamp assembly.
2. Turn the bulb socket counterclockwise and pull it straight out.
3. Pull the bulb straight out from the socket.
License Plate Lamp
To replace the bulb:
1. Reach behind the rear bumper and locate the bulb.
2. Turn the bulb socket counterclockwise and pull the bulb straight out of the
socket.
3. Replace the bulb and reverse Step 2 toreinstall.
Electrical System
Electrical System Overload
The vehicle has fuses to protect against an
electrical system overload. Fuses also protect
power devices in the vehicle.
Replace a bad fuse with a new one of the
identical size and rating.
If there is a problem on the road and a fuse
needs to be replaced, there are some spare
fuses and a fuse puller in the left
instrument panel fuse block. The
same amperage fuse can also be borrowed.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 381
When the vehicle has a flat tire (2), use the
following example as a guide to assist in the
placement of the wheel blocks (1),
if equipped.
1. Wheel Block (If Equipped)
2. Flat Tire
The following information explains how to
use the jack and change a tire.
Tire Changing
Removing the Spare Tire and Tools
1. Jack
2. Jack Knob
3. Tool Kit
4. Wing Nut Retaining Tool Kit
5. Wheel Blocks
6. Wing Nut Retaining Wheel Blocks
The equipment is under the second row
seats, if equipped, or behind the front row
seats on regular cab models.1. Turn the knob on the jack counterclockwise to lower the jack head
to release the jack from its holder. 2. Turn the wing nut counterclockwise to
remove the wheel blocks and the wheel
block retainer.
3. Turn the wing nut used to retain the storage bag and tools counterclockwise
to remove it.
Use the jack handle extensions and the
wheel wrench to remove the
underbody-mounted spare tire.1. Spare Tire (Valve Stem Pointed Down)
2. Tire/Wheel Retainer
3. Hoist Cable
4. Hoist Assembly
5. Hoist Shaft
6. Jack Handle Extensions

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
382 Vehicle Care
7. Wheel Wrench
8. Spare Tire Lock (If Equipped)
9. Hoist Shaft Access Hole
10. Hoist End of Extension Tool
1. Open the spare tire lock cover on thebumper and use the ignition key to
remove the spare tire lock (8). To remove
the spare tire lock, insert the ignition
key, turn, and pull straight out.
2. Assemble the wheel wrench (7) and thetwo jack handle extensions (6), as shown.
Spare Tire Cable (If Equipped)
3. If the vehicle is equipped with a spare tire cable disconnect the cable from the
attachment on the frame by unclipping
it from the frame attachment bracket.
4. Insert the hoist end (open end) (10) ofthe extension through the hole (9) in the
rear bumper.
Do not use the chiseled end of the wheel
wrench.
Be sure the hoist end of the
extension (10) connects to the hoist
shaft. The ribbed square end of the
extension is used to lower the spare tire.
5. Turn the wheel wrench counterclockwise to lower the spare tire to the ground.
Continue to turn the wheel wrench until
the spare tire can be pulled out from
under the vehicle.
6. Pull the spare tire out from under the vehicle.
7. Tilt the tire toward the vehicle withsome slack in the cable to access the
tire/wheel retainer.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 383
Tilt the retainer and pull it through the
center of the wheel along with the cable
and spring.
8. Put the spare tire near the flat tire.
9. If equipped with a spare tire cable remove the cable from the spare tire by
passing the clip through the looped end
of the cable.
Removing the Flat Tire and Installing the
Spare Tire
Use the following pictures and instructions
to remove the flat tire and raise the vehicle.
1. Jack
2. Wheel Blocks
3. Jack Handle
4. Jack Handle Extensions
5. Wheel Wrench
The tools you will be using include the
jack (1), the wheel blocks (2), the jack
handle (3), the jack handle extensions (4),
and the wheel wrench (5).
1. Do a safety check before proceeding. See If a Tire Goes Flat 0380.
2. If the vehicle has wheel nut caps, loosen
them by turning the wheel wrench
counterclockwise.
If the vehicle has a center cap with
wheel nut caps, the wheel nut caps are
designed to stay with the center cap
after they are loosened. Remove the
entire center cap.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
384 Vehicle Care
If the wheel has a smooth center cap,
concealing access to the wheel nuts,
place the chisel end of the wheel wrench
in the slot on the wheel, and gently pry
it out.
If the wheel’s center cap does not
conceal the wheel nuts, the center cap
may remain during wheel removal. If the
removed wheel is to be stowed in the
hoist, the cap needs to be detached from
the wheel. Access the wheel from the
back side, and use a jack handle
extension to push out the center cap.
3. Use the wheel wrench and turn itcounterclockwise to loosen the wheel
nuts. Do not remove the wheel nuts yet.
{Warning
To avoid personal injury and vehicle
damage, disable the power assist steps
before using a jack or placing an object
under the vehicle. See Power Assist Steps
0 30.
Front Position
4. If the flat tire is on the front of the vehicle, position the jack under the
bracket attached to the vehicle's frame,
behind the flat tire, as shown.

GMC Sierra/Sierra Denali 1500 Owner Manual (GMNA-Localizing-U.S./
Canada/Mexico-14632426) - 2021 - CRC - 11/5/20
Vehicle Care 385
Rear Position
5. If the flat tire is on the rear, position the jack under the rear axle about 5 cm
(2 in) inboard of the shock absorber
bracket.
{Warning
Getting under a vehicle when it is lifted
on a jack is dangerous. If the vehicle slips
off the jack, you could be badly injured
or killed. Never get under a vehicle when
it is supported only by a jack.
{Warning
Raising the vehicle with the jack
improperly positioned can damage the
vehicle and even make the vehicle fall. To
help avoid personal injury and vehicle
damage, be sure to fit the jack lift head
into the proper location before raising
the vehicle.
{Warning
The jack has a feature to limit its travel
to prevent overextension. When the
height limit is reached, an increase in
resistance if felt when attempting to
raise the jack farther. Raising the jack
past the height limit can damage the jack
pin and cause the jack to lock into an
overextended position or not lower fully.
Do not attempt to force the jack higher
once the height limit is reached.
6. Turn the wheel wrench clockwise to raise the vehicle. Raise the vehicle far enough
off the ground so there is enough room
for the spare tire to fit under the
wheel well.7. Remove all the wheel nuts and take offthe flat tire.
{Warning
Rust or dirt on a wheel, or on the
parts to which it is fastened, can
cause wheel nuts to become loose
over time. The wheel could come off
and cause a crash. When changing a
wheel, remove any rust or dirt from
places where the wheel attaches to
the vehicle. In an emergency, a cloth
or paper towel can be used; however,
use a scraper or wire brush later to
remove all rust or dirt.