2020 GMC SIERRA warning light

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
134 Instruments and Controls
Uplevel English Shown, BaseLevel and Midlevel Similar
The engine oil pressure gauge
shows the engine oil pressure
in kPa (kilopascals) or psi (pounds
per square inch) when the engine is
running.
Oil pressure can vary with engine
speed, outside temperature, coolant
temperature, and oil viscosity.
On some models, the oil pump will
vary engine oil pressure according
to engine needs. Oil pressure may
change quickly as the engine speed
or load varies. This is normal. If the
oil pressure warning light or Driver Information Center (DIC) message
indicates oil pressure outside the
normal operating range, check the
vehicle's oil as soon as possible.
See
Engine Oil 0339.
Caution
Lack of proper engine oil
maintenance can damage the
engine. Driving with the engine oil
low can also damage the engine.
The repairs would not be covered
by the vehicle warranty. Check
the oil level as soon as possible.
Add oil if required, but if the oil
level is within the operating range
and the oil pressure is still low,
have the vehicle serviced. Always
follow the maintenance schedule
for changing engine oil.
If the vehicle has a diesel engine,
see the Duramax diesel
supplement.
Engine Coolant
Temperature Gauge
Uplevel Metric Shown, Base Level and Midlevel Similar

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Instruments and Controls 135
Uplevel English Shown, BaseLevel and Midlevel Similar
This gauge measures the
temperature of the vehicle's engine
coolant.
While driving under normal
operating conditions, if the needle
moves into the red warning area,
the engine is too hot. Pull off the
road, stop the vehicle, and turn off
the engine as soon as possible.
Voltmeter Gauge
Uplevel Shown, Base Level and Midlevel Similar
When the ignition is on, this gauge
indicates the battery voltage.
When the engine is running, this
gauge shows the condition of the
charging system. The gauge can
transition from a higher to lower or a
lower to higher reading. This is
normal. If the vehicle is operating
outside the normal operating range,
the charging system light comes on.
See Charging System Light 0138. The voltmeter gauge may also read
lower when in fuel economy mode.
This is normal.
Readings outside the normal
operating range can also occur
when a large number of electrical
accessories are operating in the
vehicle and the engine is left idling
for an extended period. This
condition is normal since the
charging system is not able to
provide full power at engine idle. As
engine speeds are increased, this
condition should correct itself as
higher engine speeds allow the
charging system to create maximum
power.
The vehicle can only be driven for a
short time with the readings outside
the normal operating range. If the
vehicle must be driven, turn off all
accessories, such as the radio and
air conditioner.
Readings outside the normal
operating range indicate a possible
problem in the electrical system.
Have the vehicle serviced as soon
as possible.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Instruments and Controls 137
The airbag readiness light comes on
for several seconds when the
vehicle is started. If the light does
not come on then, have it fixed
immediately.
{Warning
If the airbag readiness light stays
on after the vehicle is started or
comes on while driving, it means
the airbag system might not be
working properly. The airbags in
the vehicle might not inflate in a
crash, or they could even inflate
without a crash. To help avoid
injury, have the vehicle serviced
right away.
If there is a problem with the airbag
system, a Driver Information Center
(DIC) message may also come on.
Passenger Airbag Status
Indicator
The vehicle has a passenger
sensing system. See Passenger
Sensing System 078 for important safety information. The overhead
console has a passenger airbag
status indicator.
United States
Canada
When the vehicle is started, the
passenger airbag status indicator
will light ON and OFF, or the
symbols for on and off, for several
seconds as a system check. Then,
after several more seconds, the
status indicator will light either ON
or OFF, or either the on or off
symbol, to let you know the status of
the front outboard passenger frontal
airbag. If the word ON or the on symbol is
lit on the passenger airbag status
indicator, it means that the front
outboard passenger frontal airbag is
allowed to inflate.
If the word OFF or the off symbol is
lit on the passenger airbag status
indicator, it means that the
passenger sensing system has
turned off the front outboard
passenger frontal airbag.
If, after several seconds, both status
indicator lights remain on, or if there
are no lights at all, there may be a
problem with the lights or the
passenger sensing system. See
your dealer for service.
{Warning
If the airbag readiness light ever
comes on and stays on, it means
that something may be wrong
with the airbag system. To help
avoid injury to yourself or others,
have the vehicle serviced right
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
138 Instruments and Controls
Warning (Continued)
away. SeeAirbag Readiness
Light 0136 for more information,
including important safety
information.
Charging System Light
The charging system light comes on
briefly when the ignition is turned
on, but the engine is not running, as
a check to show the light is working.
It should go out when the engine is
started.
If the light stays on, or comes on
while driving, there may be a
problem with the electrical charging
system. Have it checked by your
dealer. Driving while this light is on
could drain the battery. When this light comes on, or is
flashing, the Driver Information
Center (DIC) also displays a
message.
If a short distance must be driven
with the light on, be sure to turn off
all accessories, such as the radio
and air conditioner.
Malfunction Indicator
Lamp (Check Engine
Light)
This light is part of the vehicle’s
emission control on-board
diagnostic system. If this light is on
while the engine is running, a
malfunction has been detected and
the vehicle may require service. The
light should come on to show that it
is working when the ignition is on
and the engine is not running. See
Ignition Positions (Keyless Access)
0
208 or
Ignition Positions (Key Access)
0 210.
Malfunctions are often indicated by
the system before any problem is
noticeable. Being aware of the light
and seeking service promptly when
it comes on may prevent damage.
Caution
If the vehicle is driven continually
with this light on, the emission
control system may not work as
well, the fuel economy may be
lower, and the vehicle may not
run smoothly. This could lead to
costly repairs that might not be
covered by the vehicle warranty.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
140 Instruments and Controls
The DLC is under the instrument
panel to the left of the steering
wheel. Connecting devices that are
not used to perform an Emissions
Inspection/Maintenance test or to
service the vehicle may affect
vehicle operation. SeeAdd-On
Electrical Equipment 0322. See
your dealer if assistance is needed.
The vehicle may not pass
inspection if:
. The light is on when the engine
is running.
. The light does not come on
when the ignition is on while the
engine is off.
. Critical emission control systems
have not been completely
diagnosed. If this happens, the
vehicle would not be ready for
inspection and might require
several days of routine driving before the system is ready for
inspection. This can happen if
the 12-volt battery has recently
been replaced or run down, or if
the vehicle has been recently
serviced.
See your dealer if the vehicle will
not pass or cannot be made ready
for the test.
Brake System Warning
Light
MetricEnglish
This light should come on briefly
when the vehicle is turned on. If it
does not come on then, have it fixed
so it will be ready to warn you if
there is a problem.
If the light comes on and stays on at
start up, there is a brake problem.
Have the brake system inspected
right away. If the light comes on while driving,
pull off the road and stop carefully.
If equipped with electric brake
boost, vehicle speed may be limited
when the brake system warning
light comes on. The brake pedal
might be harder to push, or the
brake pedal may go closer to the
floor. It could take longer to stop.
If the light is still on, have the
vehicle towed for service. See
Towing the Vehicle
0424.
{Warning
The brake system might not be
working properly if the brake
system warning light is on.
Driving with the brake system
warning light on can lead to a
crash. If the light is still on after
the vehicle has been pulled off
the road and carefully stopped,
have the vehicle towed for
service.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Instruments and Controls 141
Electric Parking Brake
Light
MetricEnglish
This light comes on when the
parking brake is applied. If the light
continues flashing after the parking
brake is released, or while driving,
there is a problem with the Electric
Parking Brake system. A message
may also display in the Driver
Information Center (DIC).
If the light does not come on,
or remains flashing, see your dealer.
Service Electric Parking
Brake Light
This light should come on briefly
when starting the vehicle. If it does
not come on, have it fixed so it will
be ready to warn if there is a
problem.
If this light stays on, take the vehicle
to your dealer as soon as possible.
See the information for the Electric
Parking Brake under Electric
Parking Brake 0233. A message
may also display in the Driver
Information Center (DIC).
Antilock Brake System
(ABS) Warning Light
This warning light should come on
briefly when the vehicle is turned
on. If the light does not come on,
have it fixed so it will be ready to
warn if there is a problem.
If the light comes on while driving,
safely stop as soon as it is possible
and turn off the vehicle. Then turn
on the vehicle again to reset the
system.
If the ABS warning light stays on,
or comes on again while driving, the
vehicle needs service. A chime may
also sound when the light stays on.
If the ABS warning light is the only
light on, the vehicle has regular
brakes, but ABS is not functioning.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
142 Instruments and Controls
If both the ABS warning light and
the brake system warning light are
on, ABS is not functioning and there
is a problem with the regular brakes.
See your dealer for service.
SeeBrake System Warning Light
0 140.
Four-Wheel-Drive Light
Auto Mode Shown, Other Modes
Similar
If equipped, the four-wheel-drive
light displays what mode the vehicle
is in. The light will show each mode:
2WD, 4HI, AUTO (all transfer
cases); 4LOW and N (two-speed
transfer case only).
The light will flash when a shift is in
progress. Once the shift is complete
the light will be steady. If the light turns amber, there may
be a malfunction with the
four-wheel-drive system. See your
dealer.
See
Four-Wheel Drive 0227.
Tow/Haul Mode Light
For vehicles with the Tow/Haul
Mode feature, this light comes on
when the Tow/Haul Mode has been
activated.
See Tow/Haul Mode 0226.
Hill Descent Control Light
If equipped, the Hill Descent Control
light comes on when the system is
ready for use. When the light
flashes, the system is active.
See Hill Descent Control (HDC)
0 237.
Lane Departure Warning
(LDW) Light (2500/3500
Series)
If equipped, this light comes on
briefly while starting the vehicle. If it
does not come on, have the vehicle
serviced.
This light is green if LDW is on and
ready to operate.
This light changes to amber and
flashes to indicate that the lane
marking has been crossed without
using a turn signal in that direction.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
Instruments and Controls 143
SeeLane Departure Warning (LDW)
(2500/3500 Series) 0276.
Lane Keep Assist (LKA)
Light (1500 Series)
After the vehicle is started, this light
turns off and stays off if LKA has not
been turned on or is unavailable.
If available, this light is white if LKA
is turned on, but not ready to assist.
This light is green if LKA is turned
on and is ready to assist.
LKA may assist by gently turning
the steering wheel if the vehicle
approaches a detected lane
marking. The LKA light is amber
when assisting.
This light flashes amber as a Lane
Departure Warning (LDW) alert, to
indicate that the lane marking has
been crossed. LKA will not assist or alert if the turn
signal is active in the direction of
lane departure, or if LKA detects
that you are accelerating, braking,
or actively steering.
See
Lane Keep Assist (LKA) (1500
Series) 0278.
Vehicle Ahead Indicator
If equipped, this indicator will
display green when a vehicle is
detected ahead and amber when
you are following a vehicle ahead
much too closely.
See Forward Collision Alert (FCA)
System 0268.
Pedestrian Ahead
Indicator
If equipped, this indicator will
display amber when a nearby
pedestrian is detected in front of the
vehicle.
See Front Pedestrian Braking (FPB)
System (1500 Series) 0272.
Traction Off Light
This light comes on briefly while
starting the engine. If it does not,
have the vehicle serviced by your