brake light CHEVROLET LOW CAB FORWARD 2017 Service Manual

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
Driving and Operating 223
automatically when the accelerator
pedal is released and vehicle speed
is above 10 km/h (6.5 MPH).
The exhaust brake will disengage
when the accelerator pedal or brake
pedal is pressed. Releasing the
pedal reengages the exhaust brake.
Push the lever forward to turn the
exhaust brake off during idling.
{Warning
It is extremely dangerous to apply
the exhaust brake on slippery
roads as the tires can skid.
You and others could be seriously
injured.
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
depressed.
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 088.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
226 Driving and Operating
at the decreased vehicle speed.
If you want to decrease the speed
quickly, press the brake pedal to
cancel cruise control and decelerate
to the desired vehicle speed. Then,
operate the cruise control set switch
When Decreasing Vehicle Speed
Slightly
If the cruise control set switch is
operated and released immediately,
the set vehicle speed decreases
1.6 km/h (1 MPH) per operation.
This operation can be performed 6
times (3.0L diesel) or 10 times (5.2L
diesel) consecutively.When Canceling Cruise Control
Press the cruise control main switch
again to turn the cruise control
system off. The cruise control main
indicator light will go out.
The cruise control set speed is
canceled in the following cases:
.
When the brake pedal is
pressed.
. When the selector lever is
shifted to the N position. .
When cruising speed is
approximately 40 km/h (25 MPH)
or lower for 3.0L diesel , and
27 km/h (17 MPH) for the 5.2L
diesel. *
. When the vehicle speed
decreases more than 20% below
your set speed.
. When the cruise control main
switch is turned off. *
. When the engine control switch
is turned to the LOCK position. *
. When trouble develops in the
system. *
Memory speed is eliminated. *
When you do not use the cruise
control, be sure to place the cruise
control main switch into off.
When you place the engine control
switch into ACC, place the cruise
control main switch into off, then
reset the cruise control if you want
to use the cruise control again.
Using Cruise Control on Hills
How well your cruise control will
work on hills depends upon your
speed, load and the steepness of

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
Driving and Operating 227
the hills. When going up steep hills,
you may want to step on the
accelerator pedal to maintain your
speed. When going downhill, you
may have to brake or shift to a lower
gear to keep your speed down. Of
course, applying the brake takes
you out of cruise control. Many
drivers find this to be too much
trouble and do not use cruise
control on steep hills.
When Returning to Cruise Control
Driving
If you have canceled cruise control
under the following conditions, you
can return to the cruise control
driving condition before cancellation
when you operate and release the
cruise control resume switch. The
moment the resume switch is
released, the cruise set indicator
light comes on.
.When pressing the brake pedal.
. When the selector lever is
shifted to the N position.
When the vehicle speed decreases
to 30 km/h (19 MPH) or less for the
3.0L diesel, and 40 km/h (25 MPH) or less for the 5.2L diesel, it is not
possible to return to the cruise
control driving. You must reset the
cruise control.
If the cruise control is turned back
on while the vehicle speed exceeds
what is set prior to the cancellation
of cruise control, the set vehicle
speed cannot be changed until the
vehicle reaches to the set speed.
Also, the vehicle speed must be 1
MPH below the previously set
vehicle speed.
For the 5.2L diesel engine, if you
hold the switch at the +RES
position, the vehicle will keep going
faster until you release the switch or
apply the brake. So unless you want
to go faster, do not hold the switch
at the +RES position.
Exhaust Brake Function
Diesel Vehicles Equipped with
Exhaust Brake-interlocked Cruise
Automatic activation of the exhaust
brake during cruise control driving
suppresses an increase in the
speed on a downhill slope,
decreasing the need for the driver toapply the regular brake pedal. The
exhaust brake does not activate
when the exhaust brake switch is
turn off.
The maximum slope angle at which
the system can control the vehicle
speed increase is different
depending on the load the vehicle is
carrying.
Automatic Activation and
Automatic Release of Exhaust
Brake
The exhaust brake is engaged when
the vehicle speed exceeds the set
speed on a downhill slope.
The exhaust brake is disengaged
when the vehicle slows down close
to the set.
Cruise Control (Gas)
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 48 and 117 km/h (30 and
73 MPH) (48 and 97 km/h (30 and
60 MPH) for vehicles equipped with

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
Driving and Operating 229
release the accelerator pedal, the
speed returns to the original set
vehicle speed.
When Increasing Vehicle Speed
When the cruise control resume
switch is operated, the speed
increases while the switch is held.
After the speed is increased to the
desired vehicle speed, and the
switch is released, the speed is set
at the increased vehicle speed.
If you want to increase the speed
quickly, press the accelerator pedal
and accelerate to the desired
vehicle speed. Then, operate the
cruise control set switch.When Increasing Vehicle Speed
Slightly
If the cruise control resume switch is
operated and released immediately,
the set vehicle speed increases
1.6 km/h (1 MPH) per operation.
This operation can be performed 6
times (3500 model) or 10 times
(4500 model) consecutively.
When Decreasing Vehicle Speed
When the cruise control set switch
is operated, the speed decreases
while the switch is held.
After the speed is decreased to the
desired vehicle speed, and the
switch is released, the speed is setat the decreased vehicle speed.
If you want to decrease the speed
quickly, press the brake pedal to
cancel cruise control and decelerate
to the desired vehicle speed. Then,
operate the cruise control set switch
When Decreasing Vehicle Speed
Slightly
If the cruise control set switch is
operated and released immediately,
the set vehicle speed decreases
1.6 km/h (1 MPH) per operation.
This operation can be performed 6
times (3500 model) or 10 times
(4500 model) consecutively.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
230 Driving and Operating
When Canceling Cruise Control
Press the cruise control main switch
again to turn the cruise control
system off. The cruise control main
indicator light will go out.
The cruise control set speed is
canceled in the following cases:
.When the brake pedal is
pressed.
. When the selector lever is
shifted to the N or 1st position.
. When cruising speed is
approximately 40 km/h (25 MPH)
or lower. .
When the vehicle speed
decreases more than 20% below
your set speed
(3500 model only).
. When the cruise control main
switch is turned off.
. When the engine control switch
is turned to the LOCK position.
. When trouble develops in the
system.
. Memory speed is eliminated.
When you do not use the cruise
control, be sure to place the cruise
control main switch into off.
When you place the engine control
switch into ACC, place the cruise
control main switch into off, then
reset the cruise control if you want
to use the cruise control again.
Using Cruise Control on Hills
How well your cruise control will
work on hills depends upon your
speed, load and the steepness of
the hills. When going up steep hills,
you may want to step on the
accelerator pedal to maintain your
speed. When going downhill, you may have to brake or shift to a lower
gear to keep your speed down. Of
course, applying the brake takes
you out of cruise control. Many
drivers find this to be too much
trouble and do not use cruise
control on steep hills.
When Returning to Cruise Control
Driving
If you have canceled cruise control
under the following conditions, you
can return to the cruise control
driving condition before cancellation
when you operate and release the
cruise control resume switch. The
moment the resume switch is
released, the cruise set indicator
light comes on.
.
When pressing the brake pedal.
. When the selector lever is
shifted to the N or 1st position.
When the vehicle speed decreases
to 30 km/h (19 MPH) or less, it is
not possible to return to the cruise
control driving. You must reset the
cruise control.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
Driving and Operating 231
For 3500 models, if the cruise
control is turned back on while the
vehicle speed exceeds what is set
prior to the cancellation of cruise
control, the set vehicle speed
cannot be changed until the vehicle
reaches to the set speed. Also, the
vehicle speed must be 1 MPH
below the previously set vehicle
speed.
For 4500 models, if you hold the
switch at the +RES position, the
vehicle will keep going faster until
you release the switch or apply the
brake. So unless you want to go
faster, do not hold the switch at the
+RES position.Driver Assistance
Systems
Speed Limiter (Gasoline
Vehicle)
Speed limiting restricts the vehicle's
speed by controlling the fuel
injection volume. It prevents the
speed from exceeding 105 km/h
(65 mph) regardless of the pressure
on the accelerator pedal.
Speed limiting does not control
braking, so it is possible for the
vehicle to exceed the set speed on
downhill slopes. If the tire size is
changed, the speed limiting may not
work normally. Be sure to use the
correct tire size specified for your
vehicle.
SeeCruise Control (Diesel) 0224 or
Cruise Control (Gas) 0227.
Fuel
Fuel (Gasoline)
Regular unleaded gasoline with a
posted octane rating of 87 or higher
should be used. It should meet
ASTMD4814 in the U.S. and CGSB
3.5-M87 in Canada. These fuels
should contain the proper additives
and in most cases nothing should
have to be added to the fuel. Pumps
in the U.S. and Canada will be
labeled UNLEADED. Only unleaded
nozzles will fit into this vehicle's
filler neck.
Gasoline with a posted octane
rating of less than 87 should not be
used in this vehicle. Using such
gasoline may cause a heavy
knocking noise when driving, which
can result in damage to the engine.
It is normal to hear a slight pinging
noise while accelerating or driving
up a hill. However, if a constant
knocking noise is heard while using
fuel rated at 87 octane or higher, the
engine should be serviced.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
238 Driving and Operating
2. Loosen the drain plug andmove 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.
Running Out of Fuel
(Diesel)
When the Fuel Tank is Empty
When the fuel tank is empty, air will
enter the fuel system, so refueling
alone will not be enough to restart
the engine. Use the following
methods to bleed the fuel system.
Bleeding the Fuel System
Steps for Refueling
1. Follow the directions in "Parking Brake Lever" under
Parking Brake 0221.

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
276 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 a 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 Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
278 Vehicle Care
major brake problems. As such,
mixing of these two fluids can
ultimately lead to vehicle fire or
other serious accidents.
When the pump operates while the
engine is running, the fluid in the
hydro- booster will become hot.
During normal braking, the
temperature in piping and within
the hydro-booster can rise above
100 °C (212 °F). For this reason,
special care will be required when
working with hydro-booster
components. If the hydro- booster is
to be removed from the vehicle,
shut off the engine and then allow at
least 30 minutes for it to cool down
before beginning this operation.
Even when the engine is stopped,
the hydro-booster's accumulator will
remain in a highly-pressurized
condition for a significant period of
time. Before removing the
hydro-booster or piping from the
vehicle, stop the engine and
depress the brake pedal at least 10
times in order to lower the
accumulator pressure to
atmospheric pressure. This is of
particular importance whenremoving components such as the
accumulator or pressure switch from
the hydro-booster. If these
operations are attempted while the
accumulator is still at a high
pressure, hydro-booster fluid may
spray out.
Checking the Hydro-booster Fluid
Level
Check the hydro-booster fluid level
and change the fluid according to
the Maintenance Schedule.
The hydro-booster fluid level is
correct if it is between the "MAX"
and "MIN" lines. If the level is too
low, add fluid up to the "MAX" line.
Be sure to use ATF Dexron
®-VI fluid
when adding fluid. The brake
booster reservoir is located behind
the cab on the left side.
Brake Pedal
Stroke
Shut off the engine and press the
brake pedal about 10 times strongly,
then check the brake pedal for free
play by lightly pushing it by hand
until you feel resistance.
Free play (measured at the tip of pedal)
4 - 7 mm (0.16 - 0.28 in) (3500/4500)

Chevrolet Low Cab Forward Owner Manual (GMNA-Localizing-U.S.-
10716700) - 2017 - crc - 12/6/16
304 Vehicle Care
Gasoline Engine Relay LocationRelay locations:
No. Description
1 STOP LAMP
2 DAYTIME RUNNING LAMP
3 KEY ON
4 TCM
5 PARKING/NEUTRAL
6 WIPER MAIN
7 HORN
8 WIPER HI LO
9 TRAILER BRAKE
10 –/REAR POWER
WINDOW (if
equipped)
11 –/CHARGE (ENG
RUN) - Gasoline
12 POWER WINDOW
13 HEAD LAMP LO
14 VACUUM PUMP
15 HEAD LAMP HI
16 TAIL LAMP
17 CIGAR LIGHTER