2018 CHEVROLET LOW CAB FORWARD warning light

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
202 Driving and Operating
Even if the selector lever is placed
in the N position, the exhaust brake
does not disengage until the engine
is warmed up if the warm-up system
is on.
Conditions for Inoperable Exhaust
Brake
Under the following conditions, the
exhaust brake does not engage
even if the exhaust brake indicator
light comes on:
.The accelerator pedal is
pressed.
. The selector lever is in the N
position.
. The vehicle is traveling at
5 km/h (3 MPH) or lower speeds.
If your vehicle is equipped with an
anti-lock brake system (ABS), the
exhaust brake may disengage
during ABS operation even when
the exhaust brake switch is in the
ON position and the exhaust brake
indicator light is on. The exhaust
brake may disengage temporarily as
the vehicle passes over a bump
even when the brake pedal is not
pressed. It is advisable to operate the
exhaust brake when descending a
slope or when stop and go driving is
involved.
The selection of transmission gears
and engine speed when operating
the brake system is important. The
exhaust brake is more effective in
the lower gears and at the higher
engine speeds. See
Exhaust Brake
Light 078.Cruise Control
The cruise control function allows
you to drive the vehicle at a
constant speed without operating
the accelerator pedal. Use this
function when the vehicle speed is
between 40 to 160 km/h (25 to 100
MPH). This function should only be
used when driving without frequent
starts and stops.
{Warning
Cruise control can be dangerous
where you cannot drive safely at
a steady speed. Do not use
cruise control on winding roads or
in heavy traffic. You and others
could be seriously injured.
Cruise control can be dangerous
on slippery roads. On such roads,
fast changes in tire traction can
cause needless wheel spinning,
and you could lose control. Do
not use cruise control on slippery
roads. You and others could be
seriously injured.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
210 Driving and Operating
Warning (Continued)
Be sure you do not overfill the
drain pan. Heat (such as from the
engine) can cause the fuel to
expand. If the container is too full,
fuel could be forced out of the
pan. This could lead to a fire and
the risk of personal injury and/or
vehicle damage.
Biocides
In warm or humid weather, fungus,
and/or bacteria may form in diesel
fuel if there is water in the fuel.
Fungus or bacteria can cause fuel
system damage by plugging the fuel
lines, fuel filters or injector. They
can also cause fuel system
corrosion.
If fungus or bacteria has caused fuel
system problems, you should have
your authorized dealer correct these
problems. Then, use a diesel fuel
biocide to sterilize the fuel system
(follow the biocide manufacturer's
instructions). Biocides are available
from your dealer, service stations, parts stores and other automotive
places. See your authorized dealer
for advice on using biocides in your
area and for recommendations on
which biocides you should use.
Smoke Suppressants
Because of extensive testing of
treated fuel versus untreated fuel,
the use of a smoke suppressant
additive is not recommended
because of the greater possibility of
stuck rings and guttered valves,
resulting from excessive ash
deposits.
Water Separator
The purpose of the water separator
is to separate any water from the
fuel that may have formed in the
fuel tank due to condensation.
The water separator is located on
the bottom of the fuel filter.
Caution
Remaining water that is not
discharged from the water
separator could freeze and
damage the vehicle.
If the warning light comes on
while the engine is in operation,
promptly drain the water from the
water separator (fuel filter).
Continuing to drive with the light
remaining on could damage the
fuel injection system. If this
happens, have the vehicle
checked and serviced by the
nearest dealer.
Draining Water from the Fuel
Filter
Clean off any fuel that has adhered
to the vehicle body.
Starting the engine immediately
after draining the water from the fuel
filter requires a little more time than
usual. If the engine does not start in
10 seconds, wait for a while and try
again.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
Driving and Operating 211
Fuel will be mixed in the drained
water. Dispose of it in a method
conforming to the regulatory
requirements in your state.
If the water separator (fuel filter)
requires frequent draining, have the
fuel system inspected at your
dealer.
Pre Fuel Filter (Chassis-side)1. Attach a plastic hose to the drain plug (2) on the bottom of
the chassis-side fuel filter and
put the other end of the hose in
a container placed beneath the
filter. 2. Loosen the drain plug and
move the priming pump (1) up
and down by hand between
10 and 20 times.
3. Fully tighten the drain plug (2) and move the priming pump (1)
several times.
Fuel Filter (Engine-side)1. Attach a plastic hose to the drain plug (2) on the bottom of
the engine-side fuel filter (1)
and put the other end of the
hose in a container placed
beneath the filter.
2. Loosen the drain plug andmove the priming pump up and
down by hand between 10 and
20 times.
3. Fully tighten the drain plug and move the priming pump several
times.
4. Test run the engine and check that there are no fuel leaks
from the drain plug of the
engine-side fuel filter. Also
check that the water separator
(fuel filter) warning light
stays off.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
224 Vehicle Care
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.
The engine oil level must be kept at
the right level to help assure proper
lubrication of your vehicle's engine.It is the owner's responsibility to
check the oil level at regular
intervals (such as every fuel stop),
according to the following
instructions. Park the vehicle on a
level surface and check the engine
oil level before starting or at least
30 minutes after turning off the
engine.
1. Remove the oil dipstick (2) and
wipe off any oil on the oil
dipstick.
2. Reinsert the oil dipstick fullyand then gently remove it.
The oil is at the correct level if
the oil level is between the
"FULL" and "MIN" marks.
3. If the oil level is too low, add oil to the "FULL" mark.
4. Reinstall the oil dipstick into position after checking the oil
level.
Any oil level above the "FULL" mark
on the oil dipstick may cause engine
malfunctions.
The oil level cannot be checked
correctly when the engine is
running.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
Vehicle Care 231
.Dipstick H (HOT) —
Transmission fluid
temperature Approx.
70 - 80 °C (158 - 176 °F).
. The “C (COLD)” range on
the dipstick is a guide used
by your dealer for
specialized equipment used
to replace or service the
automatic transmission
fluid. When performing your
own inspections, always
use the “H (HOT)” range
after warming up the
vehicle.
The fluid must be hot to
ensure an accurate check.
The fluid level rises as
temperature increases.
6. If the fluid level is too low, add the specified fluid through the
dipstick guide tube. Also, check
whether there are no fluid
leaks.
7. Insert the dipstick securely into position.{Warning
Be extremely careful not to burn
yourself when checking the oil
level if the engine temperature is
high. Protect yourself with
gloves etc.
You and others could be seriously
injured.
Discarded parts, oil, grease and
fluids could have an adverse effect
on the environment. It is difficult to
dispose of these, so have your
dealer handle all checks and
replacements.
Engine Air Cleaner/Filter
Air Cleaner
Use of clogged air cleaner element
not only causes a deterioration in
the engine output but also increased
fuel consumption and dark exhaust
smoke. Be sure to use a genuine air cleaner
element. If other air cleaner element
is used, it may cause the sensor to
output a wrong signal.
See
Maintenance Schedule 0303.
Air Cleaner Indicator Light
When the air cleaner indicator light
comes on, check the air cleaner
element. If the air cleaner element is
clogged, replace the air cleaner
element.
See Vehicle Messages 086.
See Maintenance Schedule 0303.
Engine Coolant
Protection of Engine Against
Overcooling
Overcooling of the engine not only
accelerates wear of the vital engine
parts but also hurts fuel economy.
Engine Coolant in Cold
Weather
To prevent the engine damage due
to freezing of the engine coolant,
mix the coolant and water at the
ratio of 50/50.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
Vehicle Care 237
may be lost and damage to the
engine may result from overheating.
The radiator pressure cap should be
checked periodically for proper
operation. If a replacement is
required, a genuine GM part is
recommended.
Engine Overheating
When the Engine Overheats
The engine cooling system may
overheat if the engine coolant level
is too low, if there is a sudden loss
of engine coolant (such as radiator
hose failure), or if other problems
occur. It may also temporarily
overheat during severe operating
conditions such as:
.Climbing a long hill on a hot day.
. Stopping after high-speed
driving.
. Idling for long periods in traffic.
If engine power drops and the
needle on the engine coolant
temperature gauge goes up above
the upper limit of the safety zone
and enters the "H" zone, the engine
is overheating. The engine overheat warning light will come on and the
warning buzzer will sound. Either
steam or boiling engine coolant will
squirt out of the radiator. The
vehicle will also have an
“OVER
HEAT” message displayed. Take the
following corrective actions
immediately.
{Warning
To help avoid being burned:
Do not tilt the cab or open the
engine access cover if you see or
hear steam or engine coolant
escaping from the engine
compartment. Wait until no steam
or engine coolant can be seen or
heard before tilting the cab or
opening the engine cover.
Do not remove the radiator cap or
engine coolant reserve tank cap if
the engine coolant in the tank is
boiling. Also do not remove the
radiator cap while the engine and
radiator are still hot. Scalding fluid
(Continued)
Warning (Continued)
and steam can be blown out
under pressure if either cap is
taken off too soon.
You and others could be seriously
injured.
If Steam Is Coming from the
Engine Compartment
{Warning
If the engine coolant temperature
gauge shows an overheat
condition or you have other
reasons to suspect the engine
may be overheating, continued
operation of the engine (other
than as described here) even for
a short period of time may cause
a fire and the result in personal
injury and severe vehicle
damage. Take immediate action
as outlined.
You and others could be seriously
injured.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
242 Vehicle Care
Follow the instructions provided with
the windshield washer fluid
regarding the ratio for mixing with
tap water.
Poor quality products, engine
coolant, and soapy water must not
be used. Failure to observe this
precaution can result in nozzle
blockage or damage to painted
surfaces.
The washer should never be used
while the tank is empty. Operating
the washer with the tank empty can
result in motor damage.
Brakes
For the most effective braking and
for maximum life from brake system
components, follow these
suggestions:
.Keep any obstructions from
interfering with brake pedal
travel.
. Keep tires properly inflated.
Improperly inflated tires can
reduce the efficiency of the
brakes. 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 switch
to 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

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
11254764) - 2018 - crc - 12/5/16
Vehicle Care 243
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.Another characteristic of the HBB
system is that the brake pedal may
be pressed easily to the floor with
the vehicle at a stop. This is not a
sign of malfunction.
When the engine is running, the
system automatically charges the
accumulator whenever pressure has
been reduced after braking. Auto
charge may be activated without
braking, depending on temperature
changes in the accumulator. During
auto charge, a hissing and clicking
sound can be heard. This is not a
malfunction.
With the engine running, a booming
sound can be heard during hard
braking. This comes from the
brake-fluid pump. It is not a
malfunction.
Applying continuous hard braking
for a long time will lead to
considerable temperature rise in the
HBB pump. Such overworking of the
brakes is best avoided.
Vacuum or hydraulic power
assisted brakes
If the engine stops, do not pump the
brakes. The system is designed to
stop the vehicle with reserve power
assist if the brake pedal is held
down. This reserve is greatly
reduced each time you apply and
release the brakes. If, when you
turn the steering wheel during
braking, the vehicle does not turn,
release some pressure from the
brake pedal.
In a Vehicle Equipped with an
HBB, Do Not Keep the Brake
Pedal Pressed for an Extended
Period
Caution
Failure to follow the above
instruction will cause the oil inside
the HBB oil pump to get very hot.
This could damage the HBB tank
and deteriorate seals and also
could cause damage to the HBB
oil pump, HBB unit and/or HBB
(Continued)