check engine CHEVROLET LOW CAB FORWARD 2018 User Guide

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
Instruments and Controls 73
needle should stay in the safety
zone. SeeEngine Overheating
0 237.
{Warning
If the engine coolant temperature
gauge shows an overheat
condition or you have any other
reason to suspect the engine may
be overheating, continued
operation of the engine, even for
a short time, may result in a fire
and the risk of personal injury and
severe vehicle damage. Take
immediate action as outlined in
Engine Overheating. See Engine
Overheating 0237.
Caution
If the needle goes up above the
upper limit and enters the H zone,
the engine is likely to overheat.
Immediately pull safely off the
road out of the way of traffic and
(Continued)
Caution (Continued)
take the necessary actions to
deal with engine overheating.
If the needle nears the H zone but
does not cross into it, this is not a
problem, but check the engine
coolant level in the reservoir. Add
engine coolant as necessary.
See “Engine Overheat Warning
Light” under Driver Information
Center (DIC) 082 and Engine
Coolant 0231.
Diesel Exhaust Fluid
(DEF) Gauge
The DEF gauge is part of the Driver
Information Center (DIC). See
Driver Information Center (DIC)
082.
Seat Belt Reminders
Seat Belt Warning Light
There is a driver seat belt reminder
light on the instrument cluster.
This warning light comes on and a
warning buzzer sounds when the
driver is not wearing the seat belt
while the engine control switch is in
the ON position.
When the vehicle speed exceeds
20 km/h (12 mph) with the seat belt
unbuckled, the warning light will
flash and the buzzer will continue to
sound. The warning light will go out
and the warning buzzer will stop
when the driver buckles the
seat belt.
Battery Warning Light

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
74 Instruments and Controls
This 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 (such as a loose or broken
fan belt). Pull off to a safe place well
clear of traffic and contact your
dealer. Driving while this light is on
could drain the battery.
Check and Corrective Action1. Check to see if the fan belt is broken or loose.
2. If the fan belt is loose, adjust the tension.
3. If the fan belt is broken or there is no abnormality in the fan
belt, see your dealer for
service.
See Battery 0247, Jump Starting -
North America 0287, and Engine
Drive Belt Routing 0341.Malfunction Indicator
Lamp (Check Engine
Light)
This light should come on to show
that it is working when the engine
control switch is turned to the ON
position, and then should go out
after the engine is started.
If this light stays on or comes on
while the engine is running, it
indicates a malfunction with the
engine electronic emission control
system. Avoid driving at high
speeds and have the vehicle
inspected by your dealer.
If this light comes on when the fuel
tank is empty, you do not need to
have your vehicle serviced. See
Running Out of Fuel 0212. If this light comes on intermittently
or continuously while driving,
service is required. Even if the
vehicle is drivable and does not
require towing, see your dealer as
soon as possible. Continued driving
without having the system serviced
could cause damage to the
emission control system. It could
also affect fuel economy and
drivability.Service Vehicle Soon
Light
This light comes on briefly when the
engine control switch is in the ON
position, but the engine is not
running, as a check to show the
light is working. It should go out
when the engine is started.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
Instruments and Controls 75
If the light stays on, or comes on
while driving, the vehicle control
system may be malfunctioning. Take
the vehicle to your dealer for service
as soon as possible.
Brake System Warning
Light (Parking Brake
Light)
This light should come on briefly
when the engine control switch is
turned to the ON position, and then
should go out after the engine is
started.
Brake System Warning Light
If the light remains on after engine
start up or comes on during
operation of the vehicle, it means
that there is something wrong with
part of the brake system.The brake system warning light
comes on while the engine is
running (after startup) in the
following situations:
.
Drop in the level of brake fluid
(due to brake lining wear or fluid
leakage).
. Abnormality in the charging
system (such as an alternator
malfunction or loose or split
fan belt).
. Abnormality in the anti-lock
brake system (ABS) and
Electronic Braking force
Distribution (EBD) functions.
(The ABS warning light and
brake system warning light will
illuminate at the same time.) See
Antilock Brake System (ABS)
Warning Light 077.
To serve as a reminder, the light
should stay on when the parking
brake is not fully released, and the
engine control switch is on. Have
the system repaired if the light does
not come on when it should. If this
warning light does not go away,
brake inspection and maintenance
should be performed.
Check and Corrective Action
1. Check to see that the parking brake has been fully released.
If it has, check the following:
2. Turn on the exhaust brake to help slow the vehicle.
3. Pull off the road and stop carefully. Remember that
stopping distances may be
longer, the pedal may be
harder to push, and the pedal
may go down farther than
normal.
4. Check the brake fluid reservoir on the left side of the
instrument panel. If low, add
fluid as needed.
5. If the brake fluid is not low: Try out the brakes by starting and
stopping on the shoulder of the
road, then either drive
cautiously at a safe speed to
the nearest dealer for repair,
if you judge driving to be safe;
or have the vehicle towed to
the nearest dealer for repair.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
76 Instruments and Controls
Continued driving without the
necessary repairs could be
dangerous.
If this warning light stays on, see
your dealer.
The regular braking system is a split
system designed so that one part
will provide some braking if there is
a loss of hydraulic pressure in the
other part of the system.
{Warning
If this warning light comes on
while the engine is running,
immediately stop the vehicle at a
safe place well clear of traffic and
contact your dealer for inspection.
When the brake system warning
light is illuminated, brake
effectiveness may be decreased.
When this happens, strongly
press the brake pedal.
See Brakes 0242.
Parking Brake Light
This indicator light comes on when
the parking brake lever is pulled
with the engine control switch on.
This light also stays on when the
parking brake is not fully released
and the engine control switch is on.
If this warning light stays on, see
your dealer.
The illumination of the parking brake
light does not necessarily ensure
firm application of the parking brake.
The parking brake lever must be
sufficiently pulled up and locked.
Be careful not to drive the vehicle
with the parking brake lever still
pulled up.
Brake Low Vacuum Warning
Light
This light should come on briefly
when the engine control switch is
turned to the ON position, and then
should go out after the engine is
started. If the light does not come
on when the engine control switch is
turned to ON, it could indicate a
burned out bulb or a blown fuse.
Have the system repaired if the light
does not come on during this check.
The warning light and buzzer will
come on simultaneously when the
brake booster ’s vacuum or pressure
becomes insufficient either during
driving or when the engine control
switch is in the ON position, or when
there is an abnormality in the
charging system, such as an
alternator malfunction or loosening
or splitting of the fan belt or
whenever the hydraulic brake

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
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Instruments and Controls 77
booster (HBB) becomes faulty. The
warning buzzer will stop sounding
when the parking brake is engaged.
On 4500HD and 4500XD, the brake
low vacuum warning light and
warning buzzer should come on to
indicate low vacuum reserve for
brake power assist. At the same
time, the Back up Electric Vacuum
Pump operates.
(5500HD, 5500XD models) When
the HBB pressure is low, and/or the
HBB fluid (Dexron–VI) level is low,
the light and warning buzzer should
come on. Do not use brake fluid in
the brake booster reservoir. Use
only Dexron –VI ATF.
If this happens while driving:
. Do not pump the brakes. The
system is designed to stop the
truck with reserve power assist if
the pedal is held down. This
reserve is greatly reduced each
time you apply and release the
brakes.
. Stopping distance may be
longer. .
You may have to push much
harder on the brake pedal.
. Have the vehicle repaired before
you continue driving.
The buzzer stops when the selector
lever is shifted to the P position.
{Warning
Do not drive while the buzzer
sounds as the brakes are not
operating to their full capacity.
You and others could be seriously
injured.
Antilock Brake System
(ABS) Warning Light
This light comes on briefly when the
engine control switch is turned to
the ON position, and then should go
out after approximately three seconds. If the light does not
come on, have it fixed so it will be
ready to warn if there is a problem.
This warning light comes on
together with the brake system
warning light whenever there is a
problem in the Anti-lock Brake
System (ABS). In this case, the ABS
stops working but the brakes still
function as ordinary service brakes.
{Warning
If this warning light comes on
while driving, immediately stop
your vehicle at a safe place well
clear of traffic and take the
following actions.
1. Stop the engine.
2. Restart the engine. Check ifthe ABS warning light
comes on and then goes
out. If it does, there is no
problem. The ABS operates
normally.
(Continued)

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
78 Instruments and Controls
Warning (Continued)
3. Move the vehicle slowlyforward. Gradually increase
the speed to 15 km/h
(9 mph). If the light goes off,
the ABS is normal.
If the light does not come on or
go out, or comes on frequently,
contact your dealer immediately
and have the system repaired.
Even if a problem has occurred in
the ABS, the brakes will still work
as normal brakes. In this case,
the ABS has no influence on the
operation of the brake system.
See Brake System Warning Light
(Parking Brake Light) 075 and
Antilock Brake System (ABS) 0196.
Exhaust Brake Light
This light comes on when the
exhaust switch is pulled and the
engine is running. See Exhaust
Brake 0201.
Service Transmission
Warning Light
This light comes on briefly when the
engine control switch is in the ON
position, as a check to show the
light is working. It should go out
when the engine is started. If the warning light starts to blink
while driving, it indicates that there
is a malfunction in the automatic
transmission’s electronic control
system. If the warning light is
blinking, see your dealer for service.
Automatic Transmission
Fluid Temperature
Warning Light
This light comes on briefly when the
engine control switch is in the ON
position, but the engine is not
running, as a check to show the
light is working. It should go out
when the engine is started.
The Automatic Transmission Fluid
(ATF) Temperature warning light
comes on if the ATF temperature is
high. This usually occurs when the
transmission is overfilled and may

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
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Instruments and Controls 79
be accompanied by leakage of fluid
from the transmission
breather hose.
If the light stays on, or comes on
while driving, slow down and pull off
the road. Stop the vehicle at a safe
place and put the vehicle in
P (Park). With the engine idling, wait
until the light goes off. If the light
goes off, you can drive the vehicle
again. If the light does not go off,
have the automatic transmission
lubricating system checked by your
dealer.
Caution
Driving with the ATF warning light
constantly on can cause serious
mechanical damage to the
automatic transmission.
See Automatic Transmission 0185.
Overdrive Off Light
This light should come on briefly
when the engine control switch is
turned on as a check to make sure
the light is working. It should go out
automatically.
This light comes on when the
overdrive off switch on the selector
lever is turned on. Overdrive will not
operate even when the automatic
transmission is in D, unless engine
speed is excessive.
Wait-to-Start Light
This light comes on when the
engine control switch is turned to
the ON position and goes out when
preheating is complete.
See Starting and Stopping the
Vehicle 0149.
Engine Oil Pressure Light
This light should come on briefly
when the engine control switch is
turned to the ON position, and then
should go out after the engine is
started.
This light comes on when the
engine oil pressure has fallen below
the normal level while the engine is
running or the oil pressure across
the oil filter rises above the normal
level while the engine is running.
If the warning light comes on while
driving, immediately pull off to a
safe place and stop the engine.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
80 Instruments and Controls
Check the oil level in the engine
crankcase. If the oil level is normal,
restrictions are in the oil filter or
within the lubricating system. Have
the vehicle inspected at your dealer.
Do not run the engine with this light
on. It could damage the engine.
When this light comes on while
driving, a warning tone also sounds.
The oil level varies while the engine
is running right after it has stopped
or if the vehicle is on uneven
ground. As a result, the red engine
oil pressure warning light may
light up.
When checking the oil level, press
the engine oil level check switch on
level ground while the engine is
cool. The red engine oil pressure
warning light in combination with the
green engine oil level indicator light
can indicate if the engine oil level is
OK or low.
While driving, this light will also
activate the engine alarm and
automatic shutdown system.
SeeEngine Oil Level Indicator Light
0 80 and Engine Oil 0223.Engine Oil Level Indicator
Light
When the engine oil level check
switch is pushed with the engine
control switch in LOCK, the green
engine oil level indicator light will
come on if the engine oil level
is OK.
See Engine Oil Pressure Light 079
and Engine Oil 0223.
Diesel Exhaust Fluid
(DEF) Warning Light
This light should come on briefly
when the engine control switch is
turned to the ON position, and go off
when the engine has started.
This light comes on as a warning
related to the selective catalytic
reduction (SCR) system. If this light
comes on, check the DEF gauge.
Add DEF if necessary. If DEF level
is OK, have your vehicle serviced
by your dealer.
Also see Diesel Exhaust Fluid
0 170.
Engine Shutdown
Warning Light
The Engine Shutdown Warning light
comes on briefly when the engine
control switch is turned to the ON
position, as a check to show the
light is working. The light turns off
when the engine is started.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
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This light will come on when the
engine alarm and automatic
shutdown system is active. See
Engine Alarm and Automatic
Shutdown0155.
Idle Shutdown Light
This light comes on briefly when the
engine control switch is in the ON
position and then should go out
when the engine has started.
Idle stop is a dealer programmable
function which will automatically turn
off the engine, at idle, when specific
programmed conditions are met.
See your dealer for details.
This light comes on as an alert that
programmed conditions have been
met and the engine is about to shut
down. This light stays on after the
engine has stopped. See Idle
Shutdown 0155.
Reduced Engine Power
Light
This light comes on briefly when the
engine control switch is turned to
the ON position, and then should go
out after the engine is started.
If this light comes on while the
engine is running, it indicates power
is being reduced due to one or more
of the following conditions:
.
Malfunction of the engine or
exhaust electronic control
system.
. DEF level is too low or empty.
If this light comes on with the
malfunction indicator lamp, see your
dealer immediately. If this light comes on with the Refill
Diesel Exhaust Fluid (DEF) warning
light and the DEF warning light, refill
DEF as soon as possible.
See
“Refill Diesel Exhaust Fluid
(DEF) Warning Light” underDriver
Information Center (DIC) 082.
See Malfunction Indicator Lamp
(Check Engine Light) 074 and
Diesel Exhaust Fluid (DEF) Warning
Light 080.
High-Beam On Light
This light comes on when the
high-beam headlamps are in use or
the headlamps are cycled between
high and low beams (passing
signal).
See Headlamp High/Low-Beam
Changer 093.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
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84 Instruments and Controls
Red means the battery voltage is
too low or too high. If the voltmeter
sign appears in red, have the
vehicle checked and serviced at
your dealer. During or immediately
after the engine is started, a red
abnormal L voltage may display on
the DIC. If the warning disappears
after the engine has started, there is
no problem with the battery voltage.
Calendar and Clock
{Warning
The calendar and clock can be
set only while the vehicle is
stationary. When setting the
calendar or clock, park your
vehicle in a safe place where
stopping or parking is permitted
and that is well clear of traffic.
Press the DIC selector once or
more to select the calendar. Press
and hold the DIC selector to enter
the clock setting screen. The year
segment will flash. Turn the DIC
selector clockwise or
counterclockwise to increase or decrease the year. While in the year
setting screen, press the DIC
selector once to switch to the month
setting screen. The month segment
will flash. Use the same method to
set the month. While in the month
setting screen, press the DIC
selector again to switch to the day
setting mode. Adjust the day using
the selector.
Press and hold the DIC selector to
complete the calendar setting.
When complete, the normal
calendar display will resume. Use
this same method to set the hour
and minute when in the clock setting
screen.
Dimmer
The brightness of the DIC can be
adjusted while the light control
switch is off. Select this screen and
turn the DIC selector clockwise or
counterclockwise to brighten or dim
the illumination. The brightness is
linked to the adjustment of the
instrument panel light level control
while the light control switch is on.
See
Instrument Panel Illumination
Control 095.
Warning Lights and Messages
.
Engine Overheat Warning Light
. Low Coolant Warning Light
. Water Separator Warning Light
. Air Cleaner Light
. Low Fuel Warning Light
. Regeneration Warning Lights
. Exhaust System Warning Light
. Refill DEF Warning Light
. DIC Errors
. Maintenance Data
. Hour Meter
See Vehicle Messages 086.
Maintenance Data Functions
Display/Not Display the
Maintenance Data Function
Maintenance Light: On the DIC, go
to the Maintenance Indicator Light.
Switch the display by pressing and
holding the DIC selector for more
than two seconds. Turn the DIC
selector clockwise or
counterclockwise to switch the