warning 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
254 Vehicle Care
Follow the recommendations for
brake checks in the Maintenance
Schedule.
GM replacement brake lining
material is recommended for this
vehicle to maintain the balance
between front and rear brake
performance. GM replacement
brake parts have been carefully
selected to provide the proper brake
balance for purposes of both
stopping distance and controllability
over the full range of operating
conditions. Installation of front or
rear brake lining material with
performance different from that of
the replacement parts
recommended for this vehicle can
change the intended brake balance
of this vehicle.
Checking the Brake Electric
Vacuum Pump (4500HD/
4500XD Series)
1. Turn the engine control switchto the "ON" position (do not
start the engine), and press the
brake pedal several times. 2. Check for the noisy sound of
the electric vacuum pump
inside the instrument panel at
the same time as vacuum
warning buzzer sound, and
check that the brake low
vacuum warning light
comes on.
3. Then, start the engine. The main vacuum pump driven by
the engine will start running.
If the electric vacuum pump
operation (noisy sound) and
the vacuum warning buzzer
stop, and the brake low
vacuum warning light goes off
thereafter, the operation is
normal.
4. If you cannot hear the noisy sound or the noisy sound stays
on all the time, have the
vehicle inspected by the
nearest dealer immediately.Hydraulic Brake Booster (HBB)
The 5500HD, 5500XD models are
equipped with an HBB system. HBB
is a brake booster device that utilizes hydraulic pressure from the
HBB pump integral with the power
steering pump.
If the brake booster warning light
comes on or a warning buzzer
continues to sound, there may be a
problem with the HBB.
If this warning light comes on while
driving, immediately stop your
vehicle at a safe place well clear of
traffic and promptly contact the
nearest dealer for inspection.
Hydraulic brake booster (HBB)
characteristics
In the 5500HD, 5500XD models, an
unusual sound from under the
instrument panel may be heard from
the hydraulic system while brakes
are used. It does not mean trouble.
It is not a sign of malfunction.
If you pump the brakes with the
engine off, a squeaking sound can
be heard. This comes from the
auxiliary accumulator. It is not a
malfunction. With the engine
running, a similar sound can be
heard during sudden braking.

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
258 Vehicle Care
free of any type of damage. Check
the right front brake hose and pipe
in the same way. The rear left and
right brake hoses and pipes should
also be checked in the same
manner.
Disc Brakes and Drum Brakes
If the brake pads and shoe linings
wear out beyond their usable limit,
not only will the brake performance
be impaired, but brake components
could also fail.
{Warning
Do not drive with brake pads and
shoe linings worn out beyond the
limit. Excessively worn brake
pads and shoe linings may cause
breakdown of brake components
and poor braking performance.
You and others could be seriously
injured.
Caution
The pad has an embedded wear
indicator. A squeaking noise from
the indicator means that the pad
is approaching the usable limit.
If the squeaking noise from the
indicator can be heard, contact
the nearest dealer for inspection
or replacement.
Brake Fluid
Checking the Brake Fluid
Level
Remove the inspection cover (1) on
the left- hand side of the instrument
panel by turning it with your fingers.
Check that the fluid level in the
reservoir is between the "MAX" and
"ADD" lines.
If the fluid surface cannot easily be
seen, rock the vehicle gently.
Adding Brake Fluid
If the level of brake fluid has
dropped below the "ADD" line,
remove the cap (2) and add fluid.
Take care to avoid filling beyond the
"MAX" line.
Tighten the cap securely after the
fluid has been added.
When adding brake fluid to the tank,
take care to prevent dirt and water
from entering it. Any dirt or water in
the system could cause the vehicle
to lose braking functions.
Inspect and change brake fluid
according to the Maintenance
Schedule.
Use the recommended brake fluid
when adding brake fluid.

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
260 Vehicle Care
Remember to check and recharge
the battery as necessary, as well as
keep connection clean.
The hydrometer (green-eye test
indicator) in the top of each battery
(if equipped) provides information
for testing purposes only.
If the vehicle is not going to be
driven for 30 days or longer,
disconnect the ground cable from
the negative (–) terminal of the
batteries to prevent discharge.
For full power needs at replacement
time, a battery with the same
specifications, as shown on the
original battery's label, is
recommended.
{Warning
WARNING:Battery posts,
terminals, and related
accessories contain lead and lead
compounds, chemicals known to
the State of California to cause
cancer and birth defects or other
reproductive harm. Batteries also
(Continued)
Warning (Continued)
contain other chemicals known to
the State of California to cause
cancer.WASH HANDS AFTER
HANDLING. For more information
go to www.P65Warnings.ca.gov/
passenger-vehicle.
See California Proposition
65 Warning 0230 and the back
cover.
Fuel Filter
Change the fuel filter in accordance
with the Maintenance Schedule or
when the fuel filter indicator light
(amber) comes on.
Drain the water when the water
separator (fuel filter) warning light
comes on. (Drain the water from the
chassis-side fuel filter and
engine-side fuel filter.) Failure to replace the fuel filter when
needed may lead to fuel system
damage. Your authorized dealer can
inspect your fuel filter and replace
your fuel filter, if needed.

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
268 Vehicle Care
flasher unit will continue to operate.
Check the turn signal lamps visually
before the vehicle is used.
Bulb Wattage
{Warning
Using bulbs with a wattage other
than that specified could cause
the bulb or the wiring to become
hot. This could result in the
warping of the lens and case, and
it could also lead to the outbreak
of fire.
Bulbs are hot immediately after
they go out. When replacing the
bulbs, avoid being burned by
making sure they are fully cooled.
Never drive the vehicle with the
bulbs not working. This could
result in an accident.
You and others could be seriously
injured.When one bulb of a pair of lamps,
such as a headlamp blows out, the
other bulb is approaching the end of
its useful life. We recommend that
both be changed at the same time.
For the lamps (lighting equipment)
such as headlamps, inside of the
lens can mist up momentarily when
driving in the rain or during the car
wash. Also, the temperature
difference between inside and
outside of the lamps can sometimes
cause the water condensation
inside the lens. This is not abnormal
because this is the same
phenomenon as the windshield or
door glass fogs up when it rains.
If the mist goes away minutes after
the lamp is turned on, things are
normal.

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 269
Bulb Wattage
PositionLights Bulb Wattage (12V)Qty.
Front Headlight Highbeam/Lowbeam 60/55W2
Front Turn Signal Lamp 27W (Amber)2
Parking Lamp 5W2
Cornering Lamp 27W2
Side Turn Signal Lamp 5W (Amber)2
Sidemarker Lamp 5W (Amber)2
Rear Taillamp and Stoplamp 8/27W2
Turn Signal Lamp 27W2
Back-Up Lamp 27W2
License Plate Lamp 7.5W1
Roof Roofmarker Lamp (Identification/Clearance Lamp) 5W
5
Interior Dome Light 10W1
Speedometer and Gauge Lights 3.4W5
Warning/Indicator Lights LED20
Contact your dealer when replacing
lights that are not listed here.

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 279
{Warning
Always use fuses specified for the
vehicle. Using fuses with a rating
other than that specified, or using
wire or tin foil, etc., could result in
fire or damage.
If the new fuses blow right away
and the cause is unknown,
contact your dealer.
Do not inspect or replace fuses
when the starter switch is in the
ON position. Doing so may lead
to an accident.
When inspecting fuses, be sure to
park the vehicle on flat, level
ground and apply chocks to the
wheels.
Replacing Relays
Before replacing the relays, contact
the nearest dealer.
The vehicle may not be equipped
with all of the fuses, relays, and
features shown. It is not necessary to open or close
the cover unless trouble is found.
The relay box structure makes it
difficult for water to enter. If you
should spill water or a beverage of
the cover, however, wipe it off
before opening the cover.
The area around the cover will get
warm when the vehicle is being
driven, but this is not abnormal.

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 285
{Warning
Always use fuses specified by the
dealer when replacing the
slow-blow fuse. Using fuses with
a rating other than that specified,
or using wire or tin foil, etc., could
result in fire or damage.
If the new fuses blow right away
and the cause is unknown,
contact your dealer.
Do not inspect or replace fuses
when the starter switch is in the
ON position. Doing so may lead
to an accident.(Continued)
Warning (Continued)
When inspecting fuses, be sure to
park the vehicle on flat, level
ground and apply chocks to the
wheels.
It is not necessary to open or close
the cover unless trouble is found.
The relay box structure makes it
difficult for water to enter. If you
should spill water or a beverage of
the cover, however, wipe it off
before opening the cover.
The area around the cover will get
warm when the vehicle is being
driven, but this is not abnormal.
Wheels and Tires
The operating load and cold inflation
pressure on the rim and wheel must
not exceed the rim and wheel
manufacturer's recommendations
even though the tire may be
approved for a higher load or
inflation. Rim and wheel may be
identified (stamped) with maximum
load and maximum cold inflation
rating. For rims and wheels not so
identified or for service conditions
exceeding the rate capacities,
consult the rim and wheel
manufacturer to determine rim and
wheel capacities for the intended
service. The factory-installed tires
on this vehicle were selected to
provide the best all-around tire
performance for normal operation.
When inflated, as shown on the
vehicle, they have the load carrying
capacity to operate satisfactorily at
all loads up to and including the full
rated load specified for the vehicle.
For more information concerning the
differences in capacities of tires and

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
286 Vehicle Care
rims, refer to the“Tire and Rim
Association Inc. Yearbook”, or your
tire dealer.
Tire Inflation
{Warning
To reduce the risk of loss of
vehicle control and personal
injury:
Tires must be properly inflated,
and your vehicle must not be
overloaded (see the information
on Information on Loading the
Vehicle 046 and "Tire Load and
Inflation Table" under Tire
Pressure 0297).
Be sure to keep tires properly
inflated. A tire that is run while
seriously underinflated may
overheat to the point where the
tire may lose air suddenly and/or
catch fire, possibly resulting in
personal injury and/or property
damage. See
“Tire Load and Inflation Table”
under Tire Pressure 0297.
In no case should the front or rear
tire load exceed the maximum
recommended gross axle weight
rating (front GAWR or rear GAWR).
The efficiency of the vehicle will be
upset if air pressure in the tires are
not equal. Balanced inflation results
when the tires on the same axle
carry the same air pressure.
A difference in pressure between
the front and rear tires may be
permissible within certain limitations,
however, there should not be a
difference in pressures between the
right and left tires on the same axle.
Always use a truck tire pressure
gauge (a pocket-type gauge is not
advised) when checking inflation
pressures. Visual inspection of tires
for inflation pressures is not enough,
especially in the case of radial tires.
Underinflated radial tires may look
similar to correctly inflated radial
tires. If the inflation pressure on a
tire is found to be low frequently,
have your dealer correct the cause. Be sure to install the tire inflation
valve caps to prevent dirt and
moisture from getting into the valve
core, which could cause air leakage.
An underinflated tire in a dual wheel
assembly is harder to notice than
one in a single wheel assembly. The
properly inflated dual tire carries its
own load plus that of the
underinflated tire. Both tires can
overheat, which may result in
property damage and/or personal
injury (see previous WARNING).
Tires Used or Stored for a Long
Period of Time
Tires are a rubber product and
degrade over time, even if they are
not being used. If any of your tires is
5 to 7 years old or more, please
have them inspected for safe
driving. For further information,
please check with the tire
manufacturer.
Dual Tire Operation
The outer tire of a pair on dual
wheel installations generally wears
faster than the inner tire. If this

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 287
occurs, reverse the position of the
tires to equalize wear and get better
tire life.
In addition, when trucks are driven
continuously on high-crown roads,
an increase in air pressure of
35 kPa (5 psi) in the outer tire of a
dual tire operation will prolong outer
tire life. Be sure not to exceed the
inflation pressure limits shown on
the“VIN, Weight Rating, and
Greenhouse Gas (GHG) Emissions
Plate.” SeeVehicle Identification
Number (VIN) 0343.
Wheel and Tire Balancing
Proper tire balancing provides the
best riding comfort and helps to
reduce tire tread wear.
Out-of-balance tires can cause
annoying vehicle vibration and
uneven tire wear, such as cupping
and flat spots. See your authorized
dealer for wheel balancing.
Front End Alignment
Proper front end alignment improves
tire tread mileage. Your vehicle's
front end suspension parts should
be inspected often and aligned when needed. (See the
Maintenance Schedule for more
information.) Improper alignment will
not cause the vehicle to vibrate;
however, improper toe-in alignment
will cause front tires to roll at an
angle that will result in faster tire
wear. Incorrect caster or camber
alignment will cause your front tires
to wear unevenly, and may cause
the vehicle to "pull" to the left or
right.
Tire Traction
A decrease in driving, cornering and
braking traction occurs when water,
snow, ice, gravel or other material is
on the road surface. Driving
practices and vehicle speed should
be adjusted to the road conditions.
When driving on wet or slushy
roads, it is possible for a wedge of
water to build up between the tire
and road surface. This is known as
hydroplaning, and may cause partial
or complete loss of traction, vehicle
control and stopping ability; this
condition is also more likely with
worn tires.
To reduce the chance of traction
loss, follow these tips:
.
Slow down during rainstorms or
when roads are slushy.
. Slow down if the road has
standing water or puddles.
. Replace tires when front tread
depth is 3.2 mm (4/32 in.) and
rear tread depth is 1.6 mm
(2/32 in.).
. Keep tires properly inflated.
Tire Replacement
Recommendations
{Warning
Do not mix different construction
types of tires on your vehicle such
as radial, bias and bias-belted
tires except in emergencies,
because vehicle handling could
be affected and may result in loss
of vehicle control, or personal
injury or death. (Continued)

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
288 Vehicle Care
Warning (Continued)
Consult your dealer before
replacing wheels. Never use
wheels that are not designed for
the vehicle. Doing so would
impede safe vehicle operation.
You should replace your tires when:
. Your tires are worn to a point
where 3.2 mm (4/32 in.) (front)
and 1.6 mm (2/32 in.) (rear) or
the cord or fabric is exposed.
. Your tire tread or sidewall is
cracked, cut or snagged deeply
enough to expose the core,
fabric or steel components.
. Your tire has a hump, bulge or
split.
. Your tire sustains a puncture, cut
or other damage that cannot be
correctly repaired because of the
size or location of the damage.
When replacing tires, you should
use the same size, load range and
construction type (bias or radial) as
the original tires on your vehicle. Use of any other size or type tire
may affect load carrying capacity,
ride, handling, speedometer/
odometer calibration, vehicle ground
clearance and tire clearance to the
chassis. If replacing only a single
tire, it should be put on the same
axle with other tires of equal
diameter.
When replacing or rotating tires, all
tires on an axle should be of the
same tread design and should have
the same outside diameter within
certain limitations, particularly on
LSD models. Consult your
authorized dealer or tire dealer.