lock CHEVROLET LOW CAB FORWARD 2019 Repair Manual

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
Driving and Operating 167
Caution
After starting the engine, do not
turn the engine control switch to
the START position. Otherwise,
the starter motor may be
damaged.
Using electrical devices such as
the audio system for an extended
time period with the engine
stopped can completely discharge
the battery.
The starting circuit, engine alarm
circuits and accessory circuits are
all controlled by the engine control
switch.
1 LOCK : Lock is in the position
fully counterclockwise. In this
position, the key can be inserted or
removed. To place the engine control switch in the LOCK position,
press and hold the key in the ACC
position and then turn it to the
LOCK position. If you will leave the
vehicle, remove the key and turn the
steering wheel until it locks. The
steering wheel will be locked to help
prevent theft.
2 ACC :
Accessory is in the first
position clockwise. In this position,
the audio and other accessories can
be used with the engine stopped.
3 ON : This ON position is in the
second position clockwise. The key
stays in this position while the
engine is running. Engine control,
warning circuits, gauge circuits, and
accessory circuits are energized.
The engine cylinder heaters or glow
plugs are also turned on when the
switch is in the ON position. The
wait-to-start light will come on and
stay on until the glow plugs are
heated enough. When this light
goes off, turn the switch to the
START position.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
168 Driving and Operating
4 START :On all engines, start is in
the position furthest clockwise. The
engine is started in this position.
Turn the key against spring
pressure to energize the starter.
When key is released, spring
pressure returns it to the ON
position. Release the key as soon
as the engine has started.
If the key cannot be turned from the
LOCK position to the ON position,
lightly move the steering wheel
clockwise and counterclockwise
while trying to turn the key.
Starting and Stopping the
Vehicle
Check around the Vehicle before
Starting the Engine
Proper care and operation will not
only extend the service life of your
vehicle but also improve fuel
economy.
Before pulling away, perform a
thorough safety check, making sure
there are no children or obstructions around the vehicle. Take off the
chocks after confirming that the
parking brake is securely applied.
Sit behind the wheel, adjust the seat
position, and buckle up the seat
belt. The passengers are also
required to buckle up the seat belts.
Adjust the positions of the steering
wheel and mirrors. Lock the doors.
Turn the power of the dome light or
accessories OFF before starting the
engine. See
Seat Position 038,
Seat Belts 043, Steering Wheel
Adjustment 065, and Mirrors033.
Keep the Floor Around the
Driver's Seat Clean and Tidy{Warning
It is extremely dangerous to have
empty cans, empty bottles or
other items rolling around on the
floor because they could get
trapped under the brake pedal
and prevent brake application.
For proper pedal operation, it is (Continued)
Warning (Continued)
also essential to lay floor mats
properly. Incorrectly installed floor
mats would hinder free movement
of the pedals.
Do not use the dashboard pocket
or the top of the dashboard as a
place to put items that could roll,
which could interfere with your
driving. You and others could be
seriously injured.
Choose Your Footwear Suitable
for Driving
{Warning
Choose footwear that ensures
proper operation of pedals when
driving the vehicle. Use of
footwear unsuitable for driving
may cause an accident.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
Driving and Operating 169
Starting the Engine
Do not keep the engine control
switch in the START position for
more than about 10 seconds.
Operating the starter for too long
might cause starter and battery
failure or may result in overheating.
When the engine does not start,
wait for 20 to 30 seconds and then
turn the engine control switch again.
Before starting the engine sit in the
driver seat, check that the parking
brake is firmly engaged, the selector
lever is in the P or N (P is preferred)
position and the shift indicator also
shows P or N, and firmly press the
brake pedal to start the engine.
When stopped on a slope, start the
engine with the selector lever in the
P position. SeeIgnition Positions
0 166.
1. Make sure that the selector lever is in the P or N position
and firmly press the brake
pedal.
2. When the engine control switch
is turned to the ON position,
the wait-to-start light comes on
and it goes out in about
1 second when the engine is
warm, to about 10 seconds
when the engine is cold.
3. After confirming that the wait-to-start light has gone out,
turn the engine control switch
to the START position to start
the engine. Release the engine
control switch as soon as the
engine starts.
4. Do not crank the engine for more than 10 seconds at a
time. If the engine does not
start, wait 20 to 30 seconds
with the engine control switch
in the LOCK or ACC position
before trying to start again. It is normal for the vacuum warning
buzzer to sound for a few seconds
after the engine has started.
After the engine has started, check
to be sure the selector lever is still
in the P position.
This engine has an automatic
warm-up system that increases
engine idle speed and applies the
exhaust brake. Allow sufficient time
to let the engine circulate lubricant
oil before driving. This usually
requires 30 seconds to 2 minutes
depending on ambient conditions.
See
Brake System Warning Light
(Parking Brake Light) 074.
The turbocharged engine should be
started in a way which ensures the
bearings supporting the rotating
parts of the turbocharger are
sufficiently lubricated. Do not race a
cold engine.
At low ambient temperatures, a cold
engine may emit more smoke than
usual.
Do not drive the truck until the
engine has had sufficient time to
circulate the lubricant oil. This

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
170 Driving and Operating
usually requires 30 seconds to
2 minutes depending on ambient
conditions. This will help reduce
white start-up smoke.
Preheating :Diesel engines are
compression ignited, which makes
them difficult to start when they are
cold because the compression
alone cannot create a temperature
high enough for fuel to ignite.
Preheating means warming the
compressed air inside the
combustion chambers to facilitate
engine starting. Be sure to start the
engine after the wait-to-start light
has gone out.
Start : Do not press the accelerator
pedal at the engine start. The
accelerator opening degree at the
engine start is electronically
controlled.
Warm-up : Do not race the engine
to speed warm-up. Cold Weather Starting
If you plan ahead for cold weather,
starting and driving your vehicle
should be no problem. The following
tips will help ensure good starting in
cold weather.
Oil gets thicker as it gets colder,
which slows down the engine
cranking speed. The diesel engine
functions by the heat of
compression (and glow plugs when
cold), rather than through the use of
spark plugs as in a gasoline engine.
So, your engine must crank faster
than a gasoline engine before it will
start.
To be sure the engine can turn fast
enough to start, use SAE 10W-40
viscosity engine oil when prevailing
temperatures drop below 0 °C
(32 °F). See the oil quality and oil
viscosity recommendations. Using
the proper viscosity oil will make
starting easier down to -23 °C
(-10 °F). When prevailing
temperatures drop below -23 °C
(-10 °F), the engine block heater
may be needed for starting. See
Engine Heater
0172. Maintenance Items to Aid Cold
Weather Starting
Since the basic principle of diesel
engine ignition is based on
compression, the diesel engine is
somewhat harder to start than a
gasoline engine when the
temperature is below freezing.
To help prevent hard starting
problems, special attention should
be given to following normal
maintenance items:
1. Neglecting to have the fuel filter and water separator
serviced can be one of the
major contributors to hard
starting. If water is permitted to
accumulate in the primary filter,
it will freeze and make starting
the engine impossible.
2. Make sure the fuel tank vent is open.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
Driving and Operating 171
3. Always refuel at the end of aday's operation. Moisture will
condense in an empty tank;
therefore, the tank should be
filled before leaving the vehicle
standing for an extended
period.
Do not use starting aids in the air
intake system. Such aids can cause
immediate engine damage. See
Fuel for Diesel Engines 0227.
Stopping the Engine
When stopping the engine, take the
following steps: 1. Bring the vehicle to a complete stop.
2. Firmly apply the parking brake.
3. Move the selector lever to the P position and make sure that
the shift indicator shows P.
4. Allow the engine to idle for approximately 3 minutes.
5. Turn the engine control switch to the ACC or LOCK position. Do not shut down the engine
immediately after driving the vehicle.
Otherwise, a seizure or other
failures may result.
To prevent the battery from going
dead, turn the engine control switch
to the ACC or LOCK position after
stopping the engine. If you leave the
vehicle for an extended period of
time, place the engine control switch
in the LOCK position.
Let the engine idle for 3 minutes
before shutting off the engine. This
allows the turbocharger to slow
down while keeping the bearings
lubricated.
If the Vehicle Has Not Been Used
for a Long Period
If a diesel vehicle has been
standing for an extended period of
time, the turbocharger bearings
should be pre-lubricated prior to
starting. See your authorized dealer
for more detailed information.
Before using a vehicle that has not
been driven for a long period, check
the engine and transmission for oil
leakage, and make sure the oil is at the required levels. If there is
insufficient oil, it will not adequately
reach and lubricate components,
and a breakdown will result.
Start the engine and allow it to idle
for at least five minutes. Check for
abnormal noises.
For instructions on warming up the
engine, refer to
“Starting the Engine”
previously in this section.
If one year has passed since the
diesel exhaust fluid (DEF) in the
DEF tank was added, the DEF in
the tank should be replaced. Be
careful not to inhale the ammonia
odor when replacing the DEF. Also,
please contact your nearest dealer
about the replacement work.
Operating Temperature
Recommendations for Warming
Up the Engine
The engine is sufficiently warmed
up when the needle of the engine
coolant temperature gauge starts
to move.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
172 Driving and Operating
Do not race the engine or quickly
accelerate before the engine has
sufficiently warmed up. Oil would
not have adequately reached and
lubricated components, and a
breakdown may result.
The exhaust pipe becomes
extremely hot while the engine is
idling. Before warming up the
engine, make sure there is no
flammable material, such as grass,
waste paper, oil, or old tires near the
exhaust pipe.
Engine Warm-up System
During cold ambient conditions, the
automatic engine warm-up system
operates to reduce engine warm-up
time during idling.
Automatic Engine Warm-up :
When the engine is idling with the
engine coolant temperature below
62 °C (144 °F), the engine warm-up
system automatically closes the
exhaust brake and increases engine
idle speed so that the engine is
warmed more quickly. Warm-up is
cancelled when the accelerator
pedal is pressed, and resumedwhen the pedal is released.
Warm-up is automatically cancelled
entirely after the engine coolant
temperature rises above 65 °C
(149 °F).
Winter Cover
.
Do not cover the front of the
radiator with newspapers,
cardboard or any other
flammable material to raise the
engine coolant temperature.
. If you allow the engine to warm
up but the engine coolant
temperature does not rise, have
the nearest dealer inspect the
thermostat.
Radiator Grille Covers
{Warning
Radiator shutters, winter fronts,
or grille covers are not to be used
and may cause the engine's
radiator cooling fan to fatigue
from the alternate unloading and (Continued)
Warning (Continued)
loading of the blades as they
pass by the masked area
followed by the unmasked area.
After the fan has been fatigued, it
may suddenly break apart while
rotating, possibly causing
personal injury to anyone
standing nearby, and equipment
damage. You and others could be
seriously injured.
Engine Heater
Engine Block and Oil Pan Heater
If the vehicle is parked in a garage,
the block and pan heaters should
not be needed until the garage
temperature drops below −23°C
(−10°F) regardless of outside
temperature.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
Driving and Operating 173
The engine block and oil pan
heaters are designed to warm the
block and oil pan areas that will let
the engine run faster. To use the
heaters:1. On single cab vehicles, tilt the cab.
2. Unwrap the electrical cord and remove the protective cap.
3. Plug the cord into any three-prong 110 volt outlet
(normal household current).
It may require several hours to
sufficiently heat the engine.
Outside temperature, oil
viscosity, etc., will affect how
long the block and oil pan
heater should remain plugged
in. Contact your dealer for the
conditions in your area.
4. After using the heater(s), be sure to restore the cord
properly, to help keep it away
from moving engine parts. If the cord is too short, use a heavy
duty, three-prong extension cord. Do
not use an extension cord such as
you would use for a lamp, because
the cord may overheat.
The engine should go through a
warm-up period to warm up the
engine oil before placing engine
under load. This will ensure proper
lubrication of the engine. See
Cab
Tilting 0243.
Engine Alarm and
Automatic Shutdown
If the system senses any of the
following conditions: high engine
temperature, low engine oil pressure
or low engine coolant, the
corresponding warning light and
engine alarm (shutdown) warning
light will come on. If the engine
alarm (shutdown) warning light
comes on, you will also hear a tone
alarm.
If your vehicle has the engine
shutdown feature, your engine will
shut down in 30 seconds.
Pull safely off the road and shut off
the engine. Do not start it until the
cause of the problem is known, and
the problem is fixed. However, if the
engine shuts down when you are
still in traffic, you can restart the
engine and get another 30 seconds
of operation. Do this only if you
have to, since there is a problem
that can harm the engine if it is not
fixed. See Engine Shutdown
Warning Light 080.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
Driving and Operating 191
.Any substance other than the
DEF may cause a breakdown to
the SCR system.
. Use the DEF handling
equipment made of correct
materials (Polyethylene or
Stainless-steel).
. Avoid contamination from using
dirty funnel for filling.
. If a fluid other than the specified
DEF is mistakenly added,
incorrect fluid may cause a
failure. Have it inspected and
serviced at a dealer immediately.
. Ammonia odor may be
generated when the DEF is
exposed to high temperature.
. Do not add DEF above the F
position on the level gauge. DEF
may leak from the breather hose
while driving. Also, the sensor
may be broken when DEF
freezes.
. Do not put your feet on or stand
on the DEF tank. The tank, pipe
or sensors may be damaged. .
After stopping the engine, a flow
sound may be heard from the
DEF tank or DEF supply pump.
This sound occurs as the DEF in
the piping is returning to the
tank, and does not indicate an
abnormality.
See Winter Driving 0151.
Adding DEF
1. Turn the engine control switch to the ACC or LOCK position
and make sure to stop the
engine. 2. Wipe off dust or dirt from
around the filler port of the
DEF tank.
3. Turn and remove the filler cap.
4. Refill the tank up to the F position in the level gauge on
the front face of the tank. The
DEF may overflow from the
filler port if it is added in excess
of the F position.
5. Tighten the cap after refilling is completed.
6. Wipe off DEF that is spilled at refilling.
{Warning
On occasion, you may notice an
odor when the DEF tank is
opened. Do not sniff the filler
port, etc.
When refilling the DEF tank:
Failure to follow the above
instructions could result in a fire
or a breakdown of the selective
catalytic reduction (SCR) system.
(Continued)

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
192 Driving and Operating
Warning (Continued)
Do not dilute DEF with water.
Do not add substances such as
gasoline or diesel fuel to the DEF
tank. You and others could be
seriously injured.
Caution
When opening the DEF tank cap,
be careful not to let dirt or other
foreign matter enter inside the
DEF tank. Intrusion of foreign
matter can cause a clogging of
the filter or affect the quality of
DEF, which may result in a SCR
system failure.
If DEF is spilled on the body or
frame, it may cause generation of
rust, so wipe it off and then rinse
it away with water.When DEF dries it will leave a
crystalline residue, this condition is
normal. Wash with water or wipe
away the residue to prevent it from
entering the DEF tank.
Adding DEF in Cold Weather
DEF freezes at low temperature but
the engine coolant circulates to
thaw the DEF tank and to prevent
DEF from freezing. Vehicle can be
driven normally when DEF is frozen.
If the refill diesel exhaust fluid (DEF)
warning light is on and the
remaining DEF in the DEF tank is
frozen, the warning lights, indicator
lights and restriction will not be
canceled until the DEF thaws even
if the DEF tank is refilled.
It is not recommended parking the
vehicle for long periods with the refill
diesel exhaust fluid (DEF) warning
light on in cold weather. The DEF
gauge will not register correctly
should the DEF freeze in this
condition causing the DEF low level
warning system not to reset when DEF is added. Take the following
actions to avoid this condition in
cold weather:
1. Refill the DEF as soon as possible after parking the
vehicle.
2. Turn the engine control switch to the ON position from the
LOCK position.
3. Wait for the warning buzzers and warning lights to turn off.
4. If the buzzer does not stop, return the engine control switch
back to the LOCK position and
add more DEF, and then start
over from step (2) above.
5. Turn the engine control switch to the LOCK position.
The DEF freezes at approximately
−11 °C (12 °F).
In cold weather, when the vehicle is
left without performing these actions
and the DEF tank freezes, the low
DEF level warnings and indicators
may not turn off when DEF is added
until after the tank defrosts.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500/5500 Series (GMNA-
Localizing-U.S.-12407814) - 2019 - crc - 12/13/17
194 Driving and Operating
Selective Catalytic Reduction
(SCR) System
The Selective Catalytic Reduction
(SCR) system reduces nitrogen
oxide (NOx) emissions emitted from
a diesel engine. The SCR system
reduces NOx by adding (injecting)
Diesel Exhaust Fluid (DEF) into the
exhaust system and inducing a
reaction converting NOx into water
vapor and nitrogen.
The SCR system consists of the
DEF tank, DEF Control Unit, DEF
Supply Pump and Injector, and the
SCR Catalyst. It is important to keep
a good supply of DEF in the DEF
tank at all times. Monitor the DEF
gauge to be sure the DEF tank level
does not become too low.
If the DEF level becomes too low or
incorrect fluid is added to the DEF
tank, the warning buzzer will sound,
warning and indicator lights will
come on and engine power will be
reduced. If you see these warning
and indicator lights, add DEF as
soon as possible or have your
vehicle serviced as soon as
possible.Continuing to drive for too long after
these lights come on will result in
additional warnings, more engine
power reduction and will eventually
result in a severe vehicle speed
limitation. See
“Diesel Exhaust
Fluid (DEF) Low Level Warning” and
“Incorrect Diesel Exhaust Fluid
(DEF)/SCR System Malfunction
Warnings” later in this section.
{Warning
Do not touch the water that
comes out from the muffler. The
water is mildly acidified due to the
action of oxidation catalyst inside
the muffler. In the event that the
fluid does come into contact with
your skin, completely wash it off
with water. You and others could
be seriously injured. Do not relocate or modify the
exhaust pipe, muffler, DPF, SCR,
or DEF tank, which may affect the
exhaust gas cleaning performance.
If any relocation or modification is
necessary, consult your dealer.
The SCR system continues to
operate for approximately 3 minutes
after the engine control switch is
turned to the "LOCK" position. It is
normal to hear a buzzing type noise
from the DEF supply pump
(mounted on the left side frame rail
behind the cab) during the
shutdown process.
If it is necessary to disconnect the
batteries for any reason, be sure to
wait at least 3 minutes after turning
the engine control switch to the
"LOCK" position. This will allow the
SCR system to properly complete
its shutdown processes. See
Winter
Driving 0151.