2020 GMC SIERRA engine overheat

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
62 Seats and Restraints
Warning (Continued)
overheat. An overheated seat
heater may cause a burn or may
damage the seat.
Heated and Ventilated Seat
Buttons Shown, Heated Seat
Buttons Similar
If equipped, the buttons are on the
center stack. To operate, the engine
must be running.
Press
Ior+to heat the driver or
passenger seatback only. Press
Jorzto heat the driver or
passenger seat cushion and
seatback.
Press
Cor{to ventilate the driver
or passenger seat.
The indicator light on the button
comes on when this feature is on.
Press the button once for the
highest setting. With each press of
the button, the seat will change to
the next lower setting, and then to
the off setting. The indicator lights
next to the buttons indicate three for
the highest setting and one for the
lowest. If the heated seats are on
high for an extended time, their level
may automatically be lowered.
Auto Heated Seats
When the vehicle is on, this feature
will automatically activate the
heated seats at the level required by
the vehicle’ s interior temperature.
The active high, medium, low, or off
heated seat level will be indicated
by the manual heated seat buttons
on the center stack. Use the manual
heated seat buttons on the center stack to turn auto heated seats off.
If the passenger seat is unoccupied,
the auto heated seats feature will
not activate that seat. The auto
heated seats feature can be
programmed to always be enabled
when the vehicle is on. See
Vehicle
Personalization 0157.
Remote Start Heated and
Ventilated Seats
If equipped, the heated seats will
turn on automatically during a
remote start if it is cold outside and
the ventilated seats will turn on
automatically if it is hot outside.
If equipped, the heated steering
wheel will turn on automatically
during a remote start if it is cold
outside. The heated and ventilated
seat indicators and heated steering
wheel indicator may not come on
during this operation.
The heated and ventilated seats
and heated steering wheel may
cancel when the vehicle is started.
These features can be manually
selected after the ignition is
turned on.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Instruments and Controls 145
Engine Coolant
Temperature Warning
Light
This light comes on briefly while
starting the vehicle.
If it does not, have the vehicle
serviced by your dealer. If the
system is working normally the
indicator light goes off.
Caution
The engine coolant temperature
warning light indicates that the
vehicle has overheated. Driving
with this light on can damage the
engine and it may not be covered
by the vehicle warranty. See
Engine Overheating0351. The engine coolant temperature
warning light comes on when the
engine has overheated.
If this happens, pull over and turn
off the engine as soon as possible.
See
Engine Overheating 0351.
Driver Mode Control Light
This light comes on when Sport
Mode is selected (1500 Series).
This light comes on when Snow/Ice
Mode is selected.
This light comes on when Terrain
Mode is selected (1500 Series).
This light comes on when Off-Road
Mode is selected.
Tire Pressure Light

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 193
Warning (Continued)
cause a rollover. You could be
injured or killed. Do not drive on
steep hills.
Before driving on a hill, assess the
steepness, traction, and
obstructions. If the terrain ahead
cannot be seen, get out of the
vehicle and walk the hill before
driving further.
When driving on hills:
. Use a low gear and keep a firm
grip on the steering wheel.
. Maintain a slow speed.
. When possible, drive straight up
or down the hill.
. Slow down when approaching
the top of the hill.
. Use headlamps even during the
day to make the vehicle more
visible.
{Warning
Driving to the top of a hill at high
speed can cause a crash. There
could be a drop-off, embankment,
cliff, or even another vehicle. You
could be seriously injured or
killed. As you near the top of a
hill, slow down and stay alert.
. Never go downhill forward or
backward with either the
transmission or transfer case in
N (Neutral). The brakes could
overheat and you could lose
control.
{Warning
If the vehicle has the two-speed
automatic transfer case, shifting
the transfer case to N (Neutral)
can cause your vehicle to roll
even if the transmission is in
P (Park). This is because the
N (Neutral) position on the
(Continued)
Warning (Continued)
transfer case overrides the
transmission. You or someone
else could be injured. If leaving
the vehicle, set the parking brake
and shift the transmission to
P (Park). Shift the transfer case to
any position but N (Neutral).
. When driving down a hill, keep
the vehicle headed straight
down. Use a low gear because
the engine will work with the
brakes to slow the vehicle and
help keep the vehicle under
control.
{Warning
Heavy braking when going down
a hill can cause your brakes to
overheat and fade. This could
cause loss of control and you or
others could be injured or killed.
Apply the brakes lightly when
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 197
wet enough and you are going fast
enough. When the vehicle is
hydroplaning, it has little or no
contact with the road.
There is no hard and fast rule about
hydroplaning. The best advice is to
slow down when the road is wet.
Other Rainy Weather Tips
Besides slowing down, other wet
weather driving tips include:
.Allow extra following distance.
. Pass with caution.
. Keep windshield wiping
equipment in good shape.
. Keep the windshield washer fluid
reservoir filled.
. Have good tires with proper
tread depth. See Tires0379.
. Turn off cruise control.
Hill and Mountain Roads
Driving on steep hills or through
mountains is different than driving
on flat or rolling terrain. Tips include: .
Keep the vehicle serviced and in
good shape.
. Check all fluid levels and brakes,
tires, cooling system, and
transmission.
. Shift to a lower gear when going
down steep or long hills.
{Warning
Using the brakes to slow the
vehicle on a long downhill slope
can cause brake overheating, can
reduce brake performance, and
could result in a loss of braking.
Shift the transmission to a lower
gear to let the engine assist the
brakes on a steep downhill slope.
{Warning
Coasting downhill in N (Neutral)
or with the ignition off is
dangerous. This can cause
overheating of the brakes and
(Continued)
Warning (Continued)
loss of steering assist. Always
have the engine running and the
vehicle in gear.
. Drive at speeds that keep the
vehicle in its own lane. Do not
swing wide or cross the
center line.
. Be alert on top of hills;
something could be in your lane
(e.g., stalled car, crash).
. Pay attention to special road
signs (e.g., falling rocks area,
winding roads, long grades,
passing or no-passing zones)
and take appropriate action.
Winter Driving
Driving on Snow or Ice
Snow or ice between the tires and
the road creates less traction or
grip, so drive carefully. Wet ice can
occur at about 0 °C (32 °F) when

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 199
If it takes time for help to arrive,
when running the engine, push the
accelerator pedal slightly so the
engine runs faster than the idle
speed. This keeps the battery
charged to restart the vehicle and to
signal for help with the headlamps.
Do this as little as possible, to
save fuel.
If the Vehicle Is Stuck
Slowly and cautiously spin the
wheels to free the vehicle when
stuck in sand, mud, ice, or snow.
See“Rocking the Vehicle to Get It
Out” later in this section.
The Traction Control/Electronic
Stability Control can often help to
free a stuck vehicle. See Traction
Control/Electronic Stability Control
0 235. If TC/ESC cannot free the
vehicle, see “Rocking the Vehicle to
Get it Out” following.
{Warning
If the vehicle's tires spin at high
speed, they can explode, and you
or others could be injured. The
vehicle can overheat, causing an
engine compartment fire or other
damage. Spin the wheels as little
as possible and avoid going
above 56 km/h (35 mph).
For information about using tire
chains on the vehicle, see Tire
Chains 0404.
Rocking the Vehicle to Get
It Out
Caution
Do not hold the steering wheel at
full rotation for more than
15 seconds and/or at an elevated
RPM. Damage may occur to the
power steering system and there
may be loss of power steering
assist. Turn the steering wheel left and
right to clear the area around the
front wheels. Then make sure the
wheels are pointed straight ahead.
For four-wheel-drive vehicles, shift
into Four-Wheel Drive High. Turn
the TCS off. Shift back and forth
between R (Reverse) and a forward
gear, spinning the wheels as little as
possible. To prevent transmission
wear, wait until the wheels stop
spinning before shifting gears.
Slowly spinning the wheels in the
forward and reverse directions
causes a rocking motion that could
free the vehicle. If that does not get
the vehicle out after a few tries, it
might need to be towed out. See
Towing the Vehicle
0424. Recovery
hooks can be used, if the vehicle
has them.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Driving and Operating 213
Move the shift lever to P (Park) or
N (Neutral). 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.
Starting Procedure
1. For Key Access vehicles, turnthe ignition key to START.
When the engine starts, let go
of the key.
For Keyless Access vehicles,
the RKE transmitter must be in
the vehicle. Press ENGINE
START/STOP 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. Operate the
engine and transmission gently
to allow the oil to warm up and
lubricate all moving parts.
When the low fuel warning light
is on and the FUEL LEVEL
LOW message is displayed in
the 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
or ENGINE START/STOP 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 key or
button 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.
Stop/Start System
If equipped, the Stop/Start system
will shut off the engine to help
conserve fuel. It has components
designed for the increased number
of starts.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
216 Driving and Operating
3. Light-Duty only, remove theengine heater connector cover
by gently prying with a flat
blade tool.
4. Plug the heater cord into the connector in the front fascia.
5. Plug the cord into a grounded 110-volt AC outlet that is
protected by a ground fault
detection function.
{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
function. An ungrounded
outlet could cause an
electric shock.
. Use a weatherproof,
heavy-duty, 15 amp-rated
extension cord if needed.
Failure to use the
recommended extension
cord in good operating
condition, or using a
damaged heater or
extension cord, could make
(Continued)
Warning (Continued)
it overheat and cause a fire,
property damage, electric
shock, and injury.
. Do not operate the vehicle
with the heater cord
permanently attached to the
vehicle. Possible heater
cord and thermostat
damage could occur.
. While in use, do not let the
heater cord touch vehicle
parts or sharp edges. Never
close the hood on the
heater cord.
. Before starting the vehicle,
unplug the cord, reattach
the cover to the plug, and
securely fasten the cord.
Keep the cord away from
any moving parts.
6. Before starting the engine, be sure to unplug and store
the cord.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
218 Driving and Operating
Leaving the Vehicle with the
Engine Running
{Warning
It can be dangerous to leave the
vehicle with the engine running.
The vehicle could move suddenly
if the shift lever is not fully in
P (Park) with the parking brake
firmly set.
If you have four-wheel drive and
the transfer case is in N (Neutral),
the vehicle will be free to roll,
even if the shift lever is in
P (Park). So be sure the transfer
case is in a drive gear–not in
N (Neutral).
And, if you leave the vehicle with
the engine running, it could
overheat and even catch fire. You
or others could be injured. Do not
leave the vehicle with the engine
running unless you have to. 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 moving 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.
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 system is designed to prevent
movement of the shift lever out of
P (Park), unless the brake pedal is
applied and the ignition is on or in
Service Mode.
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 or
low voltage battery, try charging or
jump starting the battery. See Jump
Starting - North America 0419.
To shift out of P (Park): 1. Apply the brake pedal.