check engine light CHEVROLET LOW CAB FORWARD 2017 User Guide

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
84 Instruments and Controls
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 (Diesel)0238. 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.
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.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
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Instruments and Controls 85
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 EBD
functions. (The ABS warning
light and brake system warning
light will illuminate at the same
time.) See Antilock Brake
System (ABS) Warning Light
0 87.
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. For diesel vehicles, 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 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. 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 0275.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
86 Instruments and Controls
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 booster (HBB) becomes faulty. The
warning buzzer will stop sounding
when the parking brake is engaged.
On 4500, 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 (Dextron©
–III) level is
low, the light and warning buzzer
should come on. Do not use brake
fluid in the brake booster reservoir.
Use only Dextron© –III ATF.
4500 models are equipped with a
Back up Electric Vacuum Pump that
will turn on if brake booster vacuum
becomes insufficient.
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

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
Instruments and Controls 87
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.
3. Move the vehicle slowly forward. 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. (Continued)

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
88 Instruments and Controls
Warning (Continued)
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) 084 and
Antilock Brake System (ABS) 0217.
Exhaust Brake Light
For diesel vehicles, this light comes
on when the exhaust switch is
pulled and the engine is running.
See Exhaust Brake (Diesel Only)
0 222.
Service Transmission
Warning Light
For diesel vehicles, 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
For diesel vehicles, 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
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

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
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Instruments and Controls 89
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 0204.
Overdrive Off Light
(Diesel Only)
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
For diesel vehicles, 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 (Gasoline Only) 0165 or
Starting and Stopping the Vehicle
(Diesel Only) 0168.
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.
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.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
90 Instruments and Controls
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 for
Diesel engines, 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, on vehicles with the
5.2L diesel engine, this light will
also activate the engine alarm and
automatic shutdown system.
For gasoline vehicles, when this
warning light comes on, and the oil
level is correct, the lubrication
system may be faulty. See your
dealer for service.See
Engine Oil Level Indicator Light
0 90 and Engine Oil (Gasoline)
0 257 orEngine Oil (Diesel) 0251.
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 089
and Engine Oil (Gasoline) 0257 or
Engine Oil (Diesel) 0251.
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
0 189.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
Instruments and Controls 91
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.
This light will come on when the
engine alarm and automatic
shutdown system is active. See
Engine Alarm and Automatic
Shutdown (Diesel Only)0174.
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.
Diesel Engines
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) (Diesel
Only) 093.
See Malfunction Indicator Lamp
(Check Engine Light) 084 and
Diesel Exhaust Fluid (DEF) Warning
Light 090.
Gas Engines
If this light comes on while the
engine is running, this means the
engine is overheating and in
overheat protection mode. The
overheat protection mode alternates
firing groups of cylinders in order to
prevent engine damage. In this
mode, the engine loses power and
performance. This operating mode
allows your vehicle to be driven to a
safe place in an emergency. Driving
extended miles (km) and/or towing a
trailer in the overheat protection
mode should be avoided.

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Vehicle Messages
Vehicle Messages
(Diesel Only)
The Driver Information Center (DIC)
will display warnings, messages,
and other operation-related
information to alert of system
failures or other necessary checks
that should be performed. Use the
DIC selector to choose the desired
screen page or function.
Engine Overheat Warning
Light
OVERHEAT
This message displays and a
warning light appears when the
engine has overheated and the
engine coolant temperature gauge
needle reaches the red zone. At the
same time a buzzer sounds.
Immediately pull off to a safe place
to take the necessary actions and
check the vehicle. Do not shut down
an overheating engine immediately.Otherwise, the engine may seize
up. Take appropriate actions for
engine overheating.
This light will also activate the
engine alarm and automatic
shutdown system, if equipped.
See
Engine Alarm and Automatic
Shutdown (Diesel Only) 0174,
Engine Overheating 0269, Engine
Coolant 0263, and Engine Coolant
Temperature Gauge 082.
{Warning
When the engine coolant is still
hot, do not remove the radiator
cap. Hot vapor will come out and
you may be scalded. Add engine
coolant only when the engine
coolant temperature has dropped.
If this light comes on and stays on
while you are driving, your engine
coolant might have overheated
and your engine may be too hot.
You should pull off the road, stop
your vehicle and take appropriate
actions for engine overheating.
Low Coolant Warning Light
LOW COOLANT
If this message and light come on,
the system is low on engine coolant
and the engine may overheat.
A warning tone also sounds. If this
light comes on while driving, stop
the vehicle immediately and check
the cooling system for leaks. See
Engine Coolant 0263 and have the
vehicle serviced by your dealer. This
light will also activate the engine
alarm and automatic shutdown
system.
See Engine Alarm and Automatic
Shutdown (Diesel Only) 0174 and
Engine Shutdown Warning Light
0 91.
Water Separator (Fuel Filter)
Warning Light
WATER SEPARATOR
This message displays and a
warning light appears when the
level in the water separator on the
fuel line is beyond the specified
level. Drain water following the
instructions in the Water in Fuel

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
98 Instruments and Controls
section and make sure the warning
light goes out. SeeWater in Fuel
(Diesel) 0236.
If you continue driving with the
message displayed, the fuel
injection system may fail. See Water
in Fuel (Diesel) 0236.
Air Cleaner Light
CHECK AIR FILTER
This message displays and a
warning light appears when the next
air cleaner element service interval
is near or has already been
reached.
Replace the air cleaner element.
See Engine Air Cleaner/Filter 0263.
Low Fuel Warning Light
LOW FUEL
This message displays and a
warning light appears when the fuel
level in the tank becomes too low
while the engine is running. Add fuel
at the earliest possible time. If the
vehicle runs out of fuel, air bleeding
procedure must be performed. See
Fuel for Diesel Engines 0232,
Fuel Gauge 081, and Running Out
of Fuel (Diesel) 0238.
Regeneration Required
Warning Light
REGEN. REQUIRED
This light (amber) comes on when
Running regeneration or Switch
regeneration is required. When this
light comes on, perform DPF
regeneration soon. If the engine
continues to run without performing
DPF regeneration, this light will
change color from amber to red.
If this light turns red, perform DPF
regeneration immediately. If you do
not perform DPF regeneration, the
check engine malfunction indicator
light and reduced engine power
indicator light will come on,
imposing performance restriction on
the vehicle. If this happens, the
vehicle must be serviced at your
dealer. See Diesel Particulate Filter
0 180. If your vehicle is equipped with a
power take-off (PTO), monitor the
DIC for DPF related indicators. PTO
and other slow speed applications
may require more attention.Selectable (Switch)
Regeneration Required
Warning Light
SEL REGEN. REQUIRED
Performing the
“Selectable”
regeneration: After the Checking PM
Level Light is shown, this light
comes on in amber when
“Selectable” regeneration is
possible. When the DPF switch is
pressed with this light ON,
"Selectable" regeneration starts.
When the selectable regeneration or
switch regeneration is interrupted:
This light (amber) comes on when
the "Selectable" regeneration or
"Switch" regeneration is interrupted.
When this light comes on, perform
DPF regeneration promptly by
following the procedure for the
"Switch" regeneration. If you
continue to operate the vehicle
without performing DPF