low oil pressure CHEVROLET LOW CAB FORWARD 2020 Owner's Manual

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
52 Instruments and Controls
Instruments and
Controls
Controls
Steering Wheel Adjustment . . . . 53
Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Windshield Wiper/Washer . . . . . . 54
Power Outlets . . . . . . . . . . . . . . . . . 55
Warning Lights, Gauges, and
Indicators
Warning Lights, Gauges, andIndicators . . . . . . . . . . . . . . . . . . . . 56
Instrument Cluster . . . . . . . . . . . . . 57
Speedometer . . . . . . . . . . . . . . . . . . 58
Odometer . . . . . . . . . . . . . . . . . . . . . . 58
Trip Odometer . . . . . . . . . . . . . . . . . 58
Tachometer . . . . . . . . . . . . . . . . . . . . 59
Fuel Gauge . . . . . . . . . . . . . . . . . . . . 59
Engine Coolant Temperature Gauge . . . . . . . . . . . . . . . . . . . . . . . . 60
Diesel Exhaust Fluid (DEF) Gauge . . . . . . . . . . . . . . . . . . . . . . . . 60
Seat Belt Reminders . . . . . . . . . . . 60
Battery Warning Light . . . . . . . . . . 61
Malfunction Indicator Lamp (Check Engine Light) . . . . . . . . . 61
Service Vehicle Soon Light . . . . 62 Brake System Warning Light
(Parking Brake Light) . . . . . . . . . 62
Antilock Brake System (ABS) Warning Light . . . . . . . . . . . . . . . . 64
Exhaust Brake Light . . . . . . . . . . . 65
Service Transmission Warning
Light . . . . . . . . . . . . . . . . . . . . . . . . . 65
Automatic Transmission Fluid Temperature Warning Light . . . 66
Overdrive Off Light . . . . . . . . . . . . . 66
Wait-to-Start Light . . . . . . . . . . . . . 67
Engine Oil Pressure Light . . . . . . 67
Engine Oil Level Indicator Light . . . . . . . . . . . . . . . . . . . . . . . . . 67
Diesel Exhaust Fluid (DEF) Warning Light . . . . . . . . . . . . . . . . 68
Engine Shutdown Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . 68
Idle Shutdown Light . . . . . . . . . . . . 68
Reduced Engine Power Light . . . . . . . . . . . . . . . . . . . . . . . . . 69
High-Beam On Light . . . . . . . . . . . 69
Daytime Running Lamps (DRL) Indicator Light . . . . . . . . . . . . . . . . 69
Cruise Control Light . . . . . . . . . . . 70
Information Displays
Driver Information Center (DIC) . . . . . . . . . . . . . . . . . 70
Vehicle Messages
Vehicle Messages . . . . . . . . . . . . . 74
Warning Buzzers . . . . . . . . . . . . . . 79

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
Instruments and Controls 67
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.
SeeStarting and Stopping the
Vehicle 0159.
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.
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 pressurewarning 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.
See
Engine Oil Level Indicator Light
0 67 and
Engine Oil 0235.
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.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
68 Instruments and Controls
SeeEngine Oil Pressure Light 067
and
Engine Oil 0235.
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
0 180.
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 0164.
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 0164.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
138 Driving and Operating
2. To move the selector lever to"P" (Park), hold in the button
on the lever and push the lever
all the way toward the front of
your vehicle.
3. Turn the key to "LOCK".
4. Remove the key and take it with you.
5. Before you leave the driver's seat, be sure the vehicle is not
moving, or check that your
vehicle is in Park by trying to
pull the selector lever out of "P"
(Park) by pulling the selector
lever toward you without
pushing the button. If you can
do this, it means that the
selector lever was not fully
locked into "P" (Park).
Do Not Touch the Selector Lever
While the Vehicle is Stationary
with the Engine Idling
Do not touch the selector lever while
the vehicle is stationary with the
engine idling. If you touch the
selector lever at this time, a gear
could be selected and the vehicle
could move even with the parking brake applied. The risk of knocking
against the selector lever and
causing a crash is particularly great
when you move in or out of
your seat.
Driving Down a Long Slope
When driving down a long slope,
use the exhaust brake together with
the foot brake. Using the exhaust
brake and low-gears reduces the
work load on the foot brakes and
yields greater braking force. Even
so, use the foot brakes
appropriately to prevent the engine
over-revving.
Frequent use of the foot brakes can
cause vapor lock and brake fade,
resulting in reduced brake
effectiveness.
Brake Fade :
Frequent use of the
brakes can cause the brakes to
overheat so that the frictional force
of the brake linings decreases and
the brakes become less effective
than normal. This phenomenon is
called brake fade. Vapor Lock :
If the brakes overheat
due to frequent use, the heat can
cause the brake fluid to boil so that
air bubbles are created in the brake
fluid. Pressing the brake pedal
simply compresses the air bubbles;
pressure is not transmitted to the
wheel cylinders, so the brakes'
effectiveness sharply deteriorates.
This phenomenon is called
vapor lock.
Even so, you should be very careful
when using engine braking in a low
gear because the engine is likely to
over-rev. See Exhaust Brake 0213
and
Selector Lever 0205.
Do not adjust the exhaust brake
valve.
The engine should never be allowed
to exceed the governed speed.
Supplement the exhaust brake with
vehicle service brakes intermittently
and/or shift to higher transmission
gear to prevent engine overspeed.
A rule of thumb for gear selection is
that the vehicle should be driven
down a grade in the same gear that
would be used to climb that grade.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
150 Driving and Operating
SymptomCauseCorrective Action Reference
Engine is overheating No engine coolant Add engine coolant
See
Engine
Coolant 0243
Front of radiator is
clogged with dirt Wash clean with tap
waterSee
Exterior Care
0 307
Radiator cap not
sufficiently tightened Make sure it is firmly
tightened or replace the
radiator cap
-
Fan belt loose Adjust the tension or
replace the beltSee
Engine Drive
Belt Routing 0355
Engine coolant dirty
4-
Fan clutch is faulty
4-
Radiator cap dirty or
faulty Clean or replace -
Oil pressure is low Improper engine oil
viscosity
Change to an oil with
proper viscositySee
Engine Oil
0 235
Engine oil level too low Add engine oil See
Engine Oil
0 235
Engine inner
components are faulty
4-
Meter, indicator/warning
lights or switches faulty
4-

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
164 Driving and Operating
3. Plug the cord into anythree-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.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 068.
Idle Shutdown
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. When
the Idle Stop light comes on, it alerts
you that programmed conditions
have been met and the engine is
about to shut down. This light stays
on after the engine has stopped.
This indicator light will come on
when the engine control switch is
turned to the ON position and then
should go out after approximately
3 seconds.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
166 Driving and Operating
The cruise set indicator light will
stop flashing and the engine speed
will return to normal.
Engine Checks Before
Operating
Checks Before Operating
Allow the engine to warm up before
placing the engine under heavy load
driving. While the engine is warming
up under light load, the following
checks should be made:1. Observe the red engine oil pressure warning light. The
light should go out when the
engine is running. If it stays on,
shut the engine off and find the
cause.
2. Look at the engine coolant temperature gauge. If the
gauge reaches the H (HOT)
area, stop the engine and find
the cause of the overheating.
3. Check that the battery warning light has gone out. The light
should go off and stay off at
normal idle speeds. If the light does not go out or comes on
during normal operation, have
the charging system checked.
4. Check that the brake low vacuum warning light is out
and that the vacuum buzzer is
not sounding. It is normal for
the warning buzzer to sound
for a few seconds after the
engine starts. If the light and
buzzer remain on, do not drive
the vehicle until the cause has
been found and corrected.
5. Look at the brake system warning light. It should be out
when the parking brake is
released and the engine is
running. If it stays on, it could
mean that the brake fluid level
is low. Check the brake fluid
reservoir. This condition must
be corrected before moving the
vehicle.
{Warning
To reduce the chance of personal
injury and/or vehicle damage due
to engine overheating, never
leave the engine idling without an
alert driver present. If the engine
should overheat, as indicated by
the engine coolant temperature
gauge, immediate action is
required to correct the condition.
Continued operation of the
engine, even for a short time, may
result in a fire.
Do not engage the exhaust brake
while the engine is idling as this
may cause engine overheating.
You and others could be seriously
injured.
Avoid Unnecessary Idling of the
Diesel Engine
If the diesel engine idles too long,
the engine coolant temperature will
fall below the operating range. Low

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
Vehicle Care 229
Vehicle Care
General Information
General Information . . . . . . . . . . 230
California Proposition65 Warning . . . . . . . . . . . . . . . . . 230
California Perchlorate Materials Requirements . . . . . 230
Accessories and Modifications . . . . . . . . . . . . . . . . 230
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 231
Cab Tilting . . . . . . . . . . . . . . . . . . . . 233
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . . 234
Engine Cover . . . . . . . . . . . . . . . . . 235
Engine Oil . . . . . . . . . . . . . . . . . . . . 235
Automatic Transmission Fluid . . . . . . . . . . . . . . . . . . . . . . . . 241
Engine Air Cleaner/Filter . . . . . . 243
Engine Coolant . . . . . . . . . . . . . . . 243
Engine Overheating . . . . . . . . . . 249
Power Steering Fluid . . . . . . . . . 252
Washer Fluid . . . . . . . . . . . . . . . . . 252
Brakes . . . . . . . . . . . . . . . . . . . . . . . 253
Brake Fluid . . . . . . . . . . . . . . . . . . . 258
Battery - North America . . . . . . 259 Fuel Filter . . . . . . . . . . . . . . . . . . . . 260
Rear Axle (Gear Oil Viscosity
Chart) . . . . . . . . . . . . . . . . . . . . . . . 261
Rear Axle (Oil Level Check) . . . . . . . . . . . . . . . . . . . . . . 262
Noise Control System . . . . . . . . 262
Automatic Transmission Shift Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . . . 264
Wiper Blade Replacement . . . . 265
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . . . 267
Bulb Replacement
Bulb Replacement . . . . . . . . . . . . 267
Headlamps and Front Turn Signal . . . . . . . . . . . . . . . . . . . . . . . 270
Roofmarker Lamps . . . . . . . . . . . 274
Sidemarker Lamps (Including Turn Signal and Cornering
Lamps) . . . . . . . . . . . . . . . . . . . . . . 274
Taillamps, Turn Signal, Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . . . 276
License Plate Lamp . . . . . . . . . . 276
Interior Lamps . . . . . . . . . . . . . . . . 277
Electrical System
Electrical System Overload . . . 277
Wheels and Tires
Wheels and Tires . . . . . . . . . . . . . 285
Tire Pressure . . . . . . . . . . . . . . . . . 297
Tire Rotation . . . . . . . . . . . . . . . . . 297
If a Tire Goes Flat . . . . . . . . . . . . 300
Jump Starting
Jump Starting - North America . . . . . . . . . . . . . . . . . . . . . 301
Towing the Vehicle
Towing the Vehicle . . . . . . . . . . . 305
Appearance Care
Exterior Care . . . . . . . . . . . . . . . . . 307
Interior Care . . . . . . . . . . . . . . . . . . 313

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
232 Vehicle Care
chock the wheels. It would be very
dangerous if the vehicle started
to move.
When performing work on the
electrical system, begin by turning
the engine control switch to the
"LOCK" position, wait at least
3 minutes, and then disconnect the
negative cable from the negative
terminal on battery. If the negative
cable is disconnected within
3 minutes, the engine control
module may malfunction.
When working on the fuel line or
fuel filter, remove the fuel tank filler
cap. The fuel system is under
pressure and the fuel will overspill
unless the pressure is relieved,
possibly leading to combustion or
a fire.
Do not make engine adjustments
yourself. Be sure to consult your
dealer.
Use only appropriate tools.
Oils, brake fluid and engine coolant
have lubrication, cooling and rust
prevention functions. If these liquids
deteriorate through loss orcontamination, it will cause a
decline in the performance of the
parts and such problems as seizure
or malfunctioning. Replenish or
change these liquids when
performing the checks (daily and
periodic checks) as required by the
relevant regulations or in
accordance with the Maintenance
Schedule (when either the specified
driving distance or period of time,
whichever comes first, has expired).
Confirm that all systems and
components are normal after
performing the work.
Do not leave the removed parts or
tools in the engine compartment.
They could damage the equipment if
caught in the belts or other moving
components.
Dirty water, dirt and other impurities
seriously impair the effectiveness of
the oil, grease and fluids, and
damage the parts. Exercise all due
caution to prevent waste or other
refuse from coming in contact with
parts or materials that have been
removed when changing or
replenishing them.Do not step on the engine or climb
onto it. You could cause an engine
failure by, for example, damaging
the cylinder head cover or various
connectors.
Electric Welding
Careless electric welding of vehicle
parts can cause welding current to
flow back through the vehicle’s
ground circuit and damage electrical
and electronic parts so that they do
not function normally. Whenever
electric welding is necessary,
consult your dealer.

Chevrolet Low Cab Forward 5.2L Diesel Engine 4500 HD/XD/5500 HD/XD
Owner Manual (GMNA-Localizing-U.S.-13337621) - 2020 - crc - 12/5/18
236 Vehicle Care
and the oil should be changed
regularly according to the
Maintenance Schedule.
The engine oil performs the
following important functions:
.It prevents engine parts from
becoming worn.
. It cools engine parts.
. It cleans engine parts.
. It seals the combustion
chambers and prevents rust.
Replace the engine oil at regular
intervals.
When particulate matter (PM) has
accumulated to a preset level in the
diesel particulate filter (DPF), the
filter is automatically regenerated
through combustion. To make this
regeneration (combustion) possible,
a small amount of fuel is injected
into the engine combustion chamber
after firing. This causes fuel to
gradually become mixed with the
engine oil, and the engine oil level
may rise beyond the original level.
This does not indicate a malfunction
of the engine.Access to the Engine
Single Cab Model
Access to the engine oil dipstick is
located on the engine left side after
tilting the cab. See Cab Tilting
0 233.
Crew Cab Model
The engine oil dipstick is under the
engine inspection sub cover located
beneath the driver's seat.
Checking the Engine Oil Level
Press the engine oil level check
switch. If engine oil level is low the
red oil pressure warning light will
turn on. If the engine oil level is
above the "OK", the green oil level
indicator will turn on.
The oil level varies while the engine
is running, right after it is stopped,
and on sloping ground. When
checking the oil level, be sure the
vehicle is on level ground while the
engine is cool.