check engine CHEVROLET LOW CAB FORWARD 2020 Workshop 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
Driving and Operating 133
Refer toEngine Coolant 0243.
. Do not put well water, river water
or other hard water in the engine
cooling system. It would hasten
the formation of rust and scale.
. If foreign matter (insects, mud,
etc.) gets stuck in the radiator's
air passages, the cooling
system's performance will
deteriorate. Check the air
passages for clogging, and
remove any foreign matter using
water under low pressure.
Refer to Exterior Care 0307.
When Turning, the Rear
Wheels will Follow Tighter
Curves than the Front Wheels
Use the mirrors to confirm safety.
Sidewinds
If the vehicle catches a sidewind
and drifts sideways, firmly grip the
steering wheel, decelerate to a
speed that allows you to stay
completely in control, and make a directional correction. The vehicle
may catch strong sidewinds in the
following situations:
.
Emerging from a tunnel
. Driving over a bridge
. Driving on an embankment
. Driving through a cutting
. Being overtaken by a large truck
or bus
. Overtaking a large truck or bus
Flat Tire
If a blowout or flat tire occurs while
you are driving, calmly grip the
steering wheel and gradually apply
the brakes to decelerate. (Hard
braking would be dangerous
because it could cause the steering
wheel to be pulled to one side.)
Stop the vehicle in a safe place, and
change the tire.
Hard Bump Under Vehicle
If the underside of the vehicle
receives a hard bump, stop in a safe
place where the vehicle will not
obstruct traffic and check for brake fluid leakage, fuel leakage and
component damage. If any part of
the vehicle is damaged or broken,
promptly have the vehicle inspected
and repaired.
Highways
.
Speeds on highways are higher
than those on regular roads, so
there is more danger. Also, a
breakdown on a highway
represents a hazard to other
vehicles and can cause a crash.
Concentrate on safe driving.
Remember to perform daily
pre-operation inspections and
use highway driving techniques.
When performing daily
pre-operation inspections,
perform the checks shown in the
table on the left with particularly
great care.
Refer to Owner Checks and
Services 0330.
. When merging with traffic on a
highway, use the turn signal
lights to indicate your intentions
ahead of time. Speed up
sufficiently when you are in the

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
Driving and Operating 135
time, the amount of force applied to
the brake pedal and the speed of
the vehicle.
When driving, bear the stopping
distance in mind. Maintain a speed
and headway distance that allow
you to stop safely even if a hazard
occurs.
Overriding Accelerator with
Brakes
In the unlikely event the accelerator
pedal becomes stuck, apply the
brakes firmly and steadily to reduce
engine power and bring your vehicle
to a safe stop. Turn the engine off,
move the selector lever to the“P”
(Park) position, and apply the
parking brake. In a safe location,
inspect the accelerator pedal for any
interference and remove the item
causing the interference, if any is
found. If none is found and the
condition persists, have your vehicle
towed to the nearest authorized
dealer.
Braking Techniques
For the most effective braking and
for maximum life from brake system
components, follow these
suggestions when possible:
. Apply the brakes gradually as
road and load conditions permit.
Reduce pedal pressure as
speed drops so that a very light
pressure is used at the end of
the stop.
. Do not pump the brake pedal as
this will only deplete the vacuum
reserve or the hydraulic brake
booster (HBB) accumulator
reserve.
. To get maximum braking while
maintaining vehicle control, use
a "squeeze" braking technique.
Do this by pushing on the brake
pedal with steadily increasing
pressure. If possible, steer
around obstacles when there is
not enough room to stop. Brake System Warning LightCaution
If brake low vacuum warning light
(4500HD, 4500XD models), brake
booster warning light (5500HD,
5500XD models), or brake system
warning light comes on during
operation, have brake system
checked immediately.
Refer to Warning Lights, Gauges,
and Indicators 056.
When the Brakes Do Not Work
{Warning
It is very dangerous to suddenly
pull the parking brake lever all the
way while moving at high speed.
Reduce speed first by shifting
down and then gradually pull the
parking brake lever.
You and others could be seriously
injured.

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
Driving and Operating 137
Warning (Continued)
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.
The diesel particulate filter (DPF)
may automatically start
regeneration when the vehicle is
stopped and parked with the
engine running. To prevent a fire,
make sure there is no flammable
material near the muffler, DPF,
and exhaust pipe. Be careful not
to get burned by hot exhaust
gases.
You and others could be seriously
injured.Do Not Forget to Release the
Parking Brake
Pulling away with the parking brake
still applied can damage the brake
system.
Before pulling away, make sure the
parking brake is not set by checking
that the parking brake indicator light
is not on.
Be Sure to Have the Engine
Running When the Vehicle is
Moving
{Warning
When the engine is not running,
the power steering system does
not work so the steering wheel is
hard to turn. Also, the brake
booster does not work so there is
little braking ability. If you coast
down a slope without the engine
running, you would not be able to
properly control the vehicle and
could have a crash.
Parking, or Leaving
Driver
’s Seat
{Danger
It can be dangerous to get out of
your vehicle if the selector lever is
not fully in "P" (Park) or the
parking brake is not applied all
the way. Your vehicle can roll or
move suddenly.
To be sure your vehicle will not
move, even when you are parking
on level ground, follow the steps
below. (If you have to park on a
hill, also turn your front wheels so
the vehicle will roll away from
traffic.)
You and others could be seriously
injured or killed.
1. Hold the regular brake pedal down with your right foot and
apply the parking brake all the
way before shifting the
transmission. Follow the
Parking Brake instructions in
this manual for your vehicle.

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
Driving and Operating 139
{Warning
To reduce the risk of personal
injury, before going down a steep
or long grade, reduce speed, turn
on the exhaust brake and shift the
transmission to the next lower
gear. This will help control your
speed. Do not hold the brake
pedal down too long or too often
while going down a steep or long
grade. This could cause the
brakes to get hot and not to work
as well. As a result, the truck will
not slow down at the usual rate.
Failure to take these steps could
result in loss of vehicle control.
You and others could be seriously
injured.
Brake Effectiveness When the
Vehicle Has Been Driven on a
Flooded Road or Washed
{Warning
When the vehicle is driven on a
flooded road, parked on a flooded
road or washed, water can get
into the brakes and reduce their
effectiveness. If the brakes do not
work well afterward, drive slowly
and gently press the brake pedal
several times until the brakes dry
out and start working normally.
Always do this after driving
through water or washing the
vehicle to help reduce the risk of
personal injury. Before parking
the vehicle in winter, press the
brake pedal several times in the
same way to get rid of moisture in
the brakes. Otherwise, the
moisture in the brakes may freeze
and make the vehicle immovable.
You and others could be seriously
injured.If the vehicle must be driven on a
flooded road or is parked in an area
that becomes flooded, promptly
perform a check for the following
points:
.
Effectiveness of the brakes
. Water-ingress or damage to
drum brakes, disc brakes
. Engine damage due to
water-ingress
. Shorting of electrical
components
. Oil level and degradation
(cloudiness) of the engine,
transmission, differential
. Greasing of each components
(lubrication)

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
140 Driving and Operating
Steering
Do Not Leave the Steering
Wheel Fully Turned for a
Long Time
{Warning
If you leave the steering wheel
fully turned for a long time, the oil
in the power steering oil pump will
become extremely hot. This
would cause poor lubrication, oil
tank damage and seal
deterioration, leading to power
steering oil pump damage, power
steering unit damage and power
steering hose damage. As a
result the steering wheel could
become extremely hard to turn
and a fire or a crash could occur.
You and others could be seriously
injured.
Steering Wheel
If the steering parts have excess
play or looseness or if any abnormal
condition is noted, have the steering
system checked immediately.
Driving on Wet Roads
Driving on Slippery Surface or
Driving in Bad Weather (Rain,
Icy Roads, Snowy Roads, etc.)
In bad weather, visibility is reduced
and slippery road surfaces increase
stopping distances. Drive more
slowly than you would in good
weather. Also, avoid sharp turns of
the steering wheel and hard
braking. Use engine brakes together
with the foot brakes to decelerate.
Using the exhaust brake on a
slippery road surface could cause
the tires to slip.
You may not realize the surface is
slippery until the vehicle is skidding.
Learn to recognize warning clues—
such as enough water or ice on theroad to make a "mirrored surface"—
and slow down when there is any
doubt.
There is a risk of hydroplaning,
particularly where water tends to
collect on the road surface. Drive at
speeds that allow you to stay in
complete control.
If you cannot avoid driving on a
flooded road, first check the depth
of the water and then drive through
the water at a slow, constant speed.
There is a risk that water will get
into the engine's cylinders and
cause engine damage (water
hammering). Keep your speed
down, and drive with great care.
Hydroplaning :
If a vehicle is driven
at high speed on a road that is
covered with water, a layer of water
can form between the tires and road
surface, causing the tires to lose
their grip and slide across the water.
This phenomenon is called
hydroplaning. It is dangerous
because it makes the steering
wheel and brakes useless.
Refer to Wheels and Tires 0285.

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
142 Driving and Operating
Overrunning :An engine overrun is
an engine-speed increase that
causes the tachometer needle to
enter the red zone. It is dangerous
because it can cause engine failure.
Winter Driving
Recommendations for Driving
in Cold Regions
The following recommendations
apply to snowbound regions and to
mountainous regions, ski resorts
and other areas of extreme cold
and/or snowfall. Please follow them
also for reference in winter in other
regions.
For the sake of your vehicle, make
the winter preparations described in
the links below. Also have these
preparations made before driving to
a cold region.
See Engine Oil 0235.
See Engine Coolant 0243.
See Washer Fluid 0252.
See Battery - North America 0259.
When Ice Prevents You from
Putting Your Key in the Door
or Opening the Door
If you try to force the key into the
door, you could bend it. And if you
try to pull the door open with undue
force, the rubber seal around the
door could come unstuck or become
damaged. Use warm water to melt
the ice, then quickly wipe it away
and open the door.
If the wipers, electric door mirrors,
or power windows freeze up, also
use warm water to melt the ice and
then operate the system. Otherwise,
you could damage the mechanism
and drain the battery. After that,
wipe the water away.
Before Driving in Cold Regions
Getting In and Out of the Vehicle
The step can get icy in cold regions.
Be careful not to slip when getting in
and out of the vehicle. Before Sitting in the Driver
’s Seat
Remove snow and ice from your
shoes when getting into the vehicle.
If you try to drive with snow on your
shoes, your shoes would slip on the
pedals and you would not be able to
press the pedals properly, meaning
that your driving would be
inconsistent. Also, the cabin could
become more humid, causing the
glass to fog up.
Check Fuel Level
Fuel consumption increases when
tire chains are used. Determine how
much fuel you need to reach your
destination and fill up the tank in
advance. Refer to Fuel for Diesel
Engines 0218.
Removing Snow from Glass
and Underbody
Do not use a sharp implement to
remove snow. Sharp edges could
damage rubber parts.
To maintain an adequate field of
view, use a plastic scraper to
remove snow and frost from the
glass surfaces. By using a plastic

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
Driving and Operating 143
scraper, you can remove the snow
and frost without scratching the
glass. At this time, check whether
the wiper blades are frozen onto the
glass.
Also, look under the vehicle and
remove any lumps of ice that are
stuck to the underbody. Be careful
not to damage components.
Driving on Snowy or Frozen
Roads
On slippery roads, never accelerate
rapidly, brake hard, decelerate
rapidly or make sharp turns of the
steering wheel.
There is a risk of reduced grip
between the tires and road surface
and of increased braking distances.
The danger of icy road surfaces is
particularly great on bridges, in
shady places and where there are
puddles.
Keep your speed down and be sure
to use tire chains or winter tires on
snowy or frozen road surfaces.Use engine brakes together with the
foot brakes to decelerate. Using the
exhaust brake on a slippery road
surface could cause the tires to slip.
Pay Attention to the Way the
Steering Wheel Turns and Feels
On snowy roads, water and snow
splashed up by the tires can freeze
and accumulate inside the fenders,
making the steering wheel hard to
turn. From time to time, get out of
the vehicle and remove any
accumulated snow.
Check the Brakes from Time
to Time
When the vehicle is driven or
parked on a snowy surface, ice can
form on the brakes, decreasing their
effectiveness. From time to time
while you are driving, press the
brake pedal lightly and check the
effectiveness of the brakes. Pay
attention to vehicles both ahead of
and behind you when checking the
brakes in this way.
Also, check the effectiveness of the
brakes as soon as possible when
starting to drive the vehicle after ithas been parked. If the brakes do
not work well, drive slowly and
gently press the brake pedal several
times until the brakes dry out and
start working normally.
Parking in Cold Regions
When snow collects around the
wheels and the lights, try to remove
it before night falls.
Do not apply the parking brake in
extremely cold weather, such as in
temperatures or at below 0 °C (32 °
F). If you leave the parking brake
applied, the wires and brake shoes
could freeze up, making it
impossible for you to release the
parking brake. Be sure to park the
vehicle in gear.
Be sure to put chocks against the
tires.
Whenever possible, park in a
garage to help prevent parts from
freezing up and to help make the
engine easy to start.

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
148 Driving and Operating
SymptomCauseCorrective Action Reference
Unsteady engine speed There is water or air in
the fuel system
Drain water from fuel
filter or bleed the systemSee
Running Out
of Fuel 0224 or
Water in Fuel
0 221
Fuel system is faulty
4-
White exhaust smoke Engine not sufficiently
warming up
Allow the engine to
warm up
-
Too much engine oil Correct the oil level See
Engine Oil
0 235
Engine Control system
faulty
4-
Fuel system faulty
4-
Exhaust injector
4-
Continuous idling for a
long period (more than
two hours) With the vehicle
stationary in a place
where it will not obstruct
traffic, hold down the
accelerator pedal and
check that white smoke
is not emitted
-

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
154 Driving and Operating
SymptomCauseCorrective Action Reference
Loud or abnormal
noises From the
transmission
Insufficient
transmission oil
Add oilSee
Automatic
Transmission Fluid
0 241
Transmission inner
components faulty
4-
From differential Insufficient differential
gear oil
Add oilSee
Rear Axle
(Gear Oil Viscosity
Chart) 0261 or
Rear Axle (Oil
Level Check) 0262
Differential inner
components faulty
4-
From the
suspension Spring pins, shackles,
or stoppers worn
4-
From the driveshaft Poor lubrication in each
component
Lubricate themSee
Owner Checks
and Services 0330
Splines or bearings worn
4-