2018 GMC SIERRA Owner's Manual

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
144 Instruments and Controls
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
Metric, Standard Theme Shown
English, Standard Theme Shown
This gauge shows the engine
coolant temperature. Under normal
driving conditions the gauge will
read approximately 100 °C (210 °F)
or less. If the gauge pointer is near
125 °C (260 °F), the engine is
too hot.
It means that the engine coolant has
overheated. If the vehicle has been
operating under normal driving
conditions, pull off the road, stop the
vehicle, and turn off the engine as
soon as possible.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Instruments and Controls 145
Transmission
Temperature Gauge
Metric Standard Theme
English Standard Theme
This gauge appears when the
vehicle is in Tow/Haul Mode and
shows the transmission fluid
temperature. If the gauge is reading
in the red area and/or a message
appears in the Driver Information
Center (DIC), the vehicle must be
stopped and the cause checked.
One possible cause is a low fluid
level in the transmission.
Caution
Do not drive the vehicle while the
transmission fluid is overheating,
or the transmission can be
damaged. This could lead to
costly repairs that would not be
covered by the warranty.
Voltmeter Gauge
Standard Theme
When the ignition is on, this gauge
indicates the battery voltage.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
146 Instruments and Controls
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.
SeeCharging System Light 0149
for more information. 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 and unplug all
chargers and accessories.
Readings outside the normal
operating range indicate a possible
problem in the electrical system.
Have the vehicle serviced as soon
as possible.
Seat Belt Reminders
Driver Seat Belt Reminder
Light
There is a driver seat belt reminder
light on the instrument cluster.
When the vehicle is started, this
light flashes and a chime may come
on to remind the driver to fasten
their seat belt. Then the light stays
on solid until the belt is buckled.
This cycle may continue severaltimes if the driver remains or
becomes unbuckled while the
vehicle is moving.
If the driver seat belt is buckled,
neither the light nor the chime
comes on.
Passenger Seat Belt Reminder
Light
There may be a passenger seat belt
reminder light near the passenger
airbag status indicator. See
Passenger Sensing System
086.
For vehicles equipped with the
passenger seat belt reminder light,
when the vehicle is started this light
flashes and a chime may come on
to remind passengers to fasten their
seat belt. Then the light stays on
solid until the belt is buckled. This
cycle continues several times if the

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Instruments and Controls 147
passenger remains or becomes
unbuckled while the vehicle is
moving.
If the passenger seat belt is
buckled, neither the chime nor the
light comes on.
The front passenger seat belt
reminder light and chime may turn
on if an object is put on the seat
such as a briefcase, handbag,
grocery bag, laptop, or other
electronic device. To turn off the
reminder light and/or chime, remove
the object from the seat or buckle
the seat belt.
Airbag Readiness Light
This light shows if there is an
electrical problem with the airbag
system. The system check includes
the airbag sensor(s), passenger
sensing system (if equipped), the
pretensioners, the airbag modules,
the wiring, and the crash sensing
and diagnostic module. For more
information on the airbag system,
seeAirbag System 077.
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.
Airbag On-Off Light
If the vehicle has an airbag on-off
switch, it also has a passenger
airbag status indicator located in the
overhead console.
United States
Canada and Mexico
When the vehicle is started, the
passenger airbag status indicator
ON and OFF, or the symbol for on
and off, will light for several seconds
as a system check. Then, after
several more seconds, the status
indicator ON or OFF, or either the

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
148 Instruments and Controls
on or off symbol, will light to let you
know the status of the front
outboard passenger frontal airbag.
When the front outboard passenger
frontal airbag is manually turned off
using the airbag on-off switch on the
instrument panel endcap, the OFF
indicator light or the off symbol will
come on and stay on as a reminder
that the airbag has been turned off.
This light will go off when the airbag
has been turned on. SeeAirbag
On-Off Switch 084 for more
information, including important
safety information.{Warning
If the front outboard passenger
frontal airbag is turned off for a
person who is not in a risk group
identified by the national
government, that person will not
have the extra protection of an
airbag. In a crash, the airbag will
not be able to inflate and help
protect the person sitting there.
Do not turn off the front outboard
passenger frontal airbag unless
the person sitting there is in a risk
group identified by the national
government. See Airbag On-Off
Switch 084 for more information,
including important safety
information.
{Warning
If the airbag readiness light ever
comes on and stays on, it means
that something may be wrong
(Continued)
Warning (Continued)
with the airbag system. For
example, the front outboard
passenger frontal airbag could
inflate even though the airbag
on-off switch is turned off.
To help avoid injury to yourself or
others, have the vehicle serviced
right away. SeeAirbag Readiness
Light 0147 for more information,
including important safety
information.
If the word ON or the on symbol is
lit, it means that the front outboard
passenger frontal airbag is enabled
(may inflate). See Airbag On-Off
Switch 084 for more information,
including important safety
information.
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 airbag
on-off switch. See your dealer for
service.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Instruments and Controls 149
Passenger Airbag Status
Indicator
If the vehicle has the passenger
sensing system, the overhead
console will have a passenger
airbag status indicator. See
Passenger Sensing System086 for
important safety information.
United States
Canada and Mexico
When the vehicle is started, the
passenger airbag status indicator
will light ON and OFF, or the symbol
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 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
(Continued)
Warning (Continued)
with the airbag system. To help
avoid injury to yourself or others,
have the vehicle serviced right
away. SeeAirbag Readiness
Light 0147 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

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
150 Instruments and Controls
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 Positions0256.
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.
Caution
Modifications to the engine,
transmission, exhaust, intake,
or fuel system, or the use of
replacement tires that do not
meet the original tire
specifications, can cause this light
to come on. This could lead to
costly repairs not covered by the
vehicle warranty. This could also
affect the vehicle’s ability to pass
an Emissions Inspection/
Maintenance test. See
Accessories and Modifications
0343.
If the light is flashing : A
malfunction has been detected that
could damage the emission control
system and increase vehicle
emissions. Diagnosis and service
may be required.
To help prevent damage, reduce
vehicle speed and avoid hard
accelerations and uphill grades.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-11349177) - 2018 - CRC - 10/17/17
Instruments and Controls 151
If towing a trailer, reduce the
amount of cargo being hauled as
soon as possible.
If the light continues to flash, find a
safe place to park. Turn the vehicle
off and wait at least 10 seconds
before restarting the engine. If the
light is still flashing, follow the
previous guidelines and see your
dealer for service as soon as
possible.
If the light is on steady :A
malfunction has been detected.
Diagnosis and service may be
required.
Check the following:
. A loose or missing fuel cap may
cause the light to come on. See
Filling the Tank 0301. A few
driving trips with the cap
properly installed may turn the
light off.
. Poor fuel quality can cause
inefficient engine operation and
poor driveability, which may go
away once the engine is warmed
up. If this occurs, change the
fuel brand. It may require at least one full tank of the proper
fuel to turn the light off. See
Fuel
0 299.
If the light remains on, see your
dealer.
Emissions Inspection and
Maintenance Programs
If the vehicle requires an Emissions
Inspection/Maintenance test, the
test equipment will likely connect to
the vehicle's Data Link
Connector (DLC).
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. See Add-On
Electrical Equipment 0336. 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.