
•
A drop in engine RPM, depending on
grade and vehicle load, during a
descent.
• A decrease in road speed when
applying the exhaust brake during a
descent, except when your vehicle is
carrying a heavy load or the grade is
extremely steep. In these instances,
you may need to apply the service
brakes occasionally.
TRAILER BRAKES
Trailer Brake Hand Control (If Equipped) WARNING: The hand control
should never be used to apply the brakes
when the tractor and trailer are parked
unattended. Air may leak from the
system and the vehicle could possibly
move, resulting in possible property
damage, personal injury or death. The hand control is located on the
right-hand side of the instrument panel. It
applies the trailer service brakes, which are
independent of the truck or tractor service
brakes.
It operates a valve that provides gradual
control of air pressure applied. When the
valve is only partially applied, you can
override the trailer brakes by pressing fully
on the brake pedal. To apply the trailer brakes using the hand
control, move the lever downward. The
further you push the lever down, the
greater the air pressure is applied to the
brakes. The lever remains in place until
manually moved.
To release the trailer brakes, move the
lever up completely.
Trailer Air Supply and Parking
Brake Modular Controls
(If Equipped)
The trailer air supply valve delivers air to
the trailer supply and automatically pops
out, shutting off the trailer supply, if
pressure decreases to approximately 35 psi
(249 kPa)
.
The parking brake controls the spring
brakes on the tractor. When you pull the
knob out, it causes the trailer supply valve
to pop out, applying both the tractor and
trailer parking brakes. You can
independently release the trailer brakes by
pushing only the trailer air supply valve in.
138
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210339 E210340
A
B
12
A320
A E210341

Initial Charge
With the air system completely discharged,
both knobs (A and B) are out. When the
air pressure reaches 70 psi (481 kPa), the
trailer air supply (A - red knob) may be
pushed in and should stay in, charging the
trailer air system and releasing the trailer
brakes. You can push in the parking brake (B -
yellow knob) and supply air to the tractor
spring brakes, releasing them.
Normal Driving Position
Push in both knobs (A and B) to supply air
to both trailer and tractor spring brakes,
releasing all brakes.
139
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210342 E210343 E210343

System Park
With both knobs (A and B) pushed in
(normal driving position), the parking
brakes for both the tractor and trailer can
be applied by pulling the parking brake
knob (B) out, exhausting air from the
tractor spring brakes, simultaneously
causing the trailer air supply valve to pop
out, applying the trailer brakes.
Trailer Charge
If both knobs (A and B) are out, and you
want to recharge the trailer while leaving
the tractor spring brakes applied, the trailer
air supply (A) can be pushed in to recharge
the trailer air supply line. You can also use
this mode to park a combination vehicle
with tractor spring brakes.
140
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210344 E210342

Automatic Application
If both knobs (A and B) are pushed in and
the brake system air pressure is reduced
to approximately 35 psi (249 kPa), the
trailer air supply (A) knob automatically
pops out applying the emergency or
parking brakes on the trailer. If the trailer
air supply (A) knob is manually held in and
the air pressure is reduced to
approximately
30 psi (207 kPa), a tripper
piston within the valve moves, exhausting
the trailer air supply, applying the trailer
brakes. Further reduction of air pressure,
while holding the trailer air supply knob in,
causes the parking brake knob to pop out
at
25 psi (172 kPa).
Actuation of Trailer Park (Emergency)
or Tractor Bobtail Position To actuate the trailer brakes only, pull out
the trailer air supply (A) knob. This applies
the trailer brakes whether the trailer uses
emergency or spring brakes.
You can also use this mode when the
tractor or truck with trailer is used during
bobtail operation.
141
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing BrakesE210345 E210345

PRINCIPLE OF OPERATION
The traction control system helps avoid
drive wheel spin and loss of traction.
If your vehicle begins to slide, the system
applies the brakes to individual wheels
and, when needed, reduces engine power
at the same time. If the wheels spin when
accelerating on slippery or loose surfaces,
the system reduces engine power in order
to increase traction.
Note:
The system does not apply the brakes
when vehicle speed is above 25 mph
(40 km/h).
USING TRACTION CONTROL -
VEHICLES WITH: AIR BRAKES WARNING:
The stability and
traction control light illuminates steadily
if the system detects a failure. Make sure
you did not manually disable the traction
control system using the information
display controls or the switch. If the
stability control and traction control light
is still illuminating steadily, have the
system serviced by an authorized dealer
immediately. Operating your vehicle with
the traction control disabled could lead
to an increased risk of loss of vehicle
control, vehicle rollover, personal injury
and death. Press the TCS Off button on the
instrument panel to enable the
mud/snow mode.
This is beneficial when your vehicle is stuck
in snow or on a slippery road surface. This
mode allows wheel spin to dig your vehicle
out and allows you to rock your vehicle. Press the switch again to select standard
traction control. The system automatically
selects standard traction control at the
next ignition cycle.
System Indicator Light
Note:
If the traction control light does not
flash during a traction control event or stays
illuminated, the system is not functioning
properly. Take your vehicle to an authorized
dealer for service.
During traction control operation, the
traction control light flashes rapidly and
the engine does not rev-up when you press
further on the accelerator. This is normal
and is no reason for concern.
In Mud/Snow mode, the TCS OFF light
illuminates on the instrument cluster. If a
traction event occurs in either mode, the
Stability Control and Traction Control light
flashes rapidly.
USING TRACTION CONTROL -
VEHICLES WITH: HYDRAULIC
BRAKES WARNING:
Aggressive driving in
any road conditions can cause you to
lose control of your vehicle increasing
the risk of severe personal injury or
property damage. The traction control
activating is an indication that at least
some of the tires have exceeded their
ability to grip the road; this may lead to
an increased risk of loss of vehicle
control, vehicle rollover, personal injury
and death. If you experience a severe
road event, slow down
.
The system turns on each time you switch
the ignition on.
142
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing Traction ControlE330660

PRINCIPLE OF OPERATION -
VEHICLES WITH: HYDRAULIC
BRAKES
WARNING: Vehicle modifications
involving braking system, aftermarket
roof racks, suspension, steering system,
tire construction and wheel and tire size
may change the handling characteristics
of your vehicle and may adversely affect
the performance of the electronic
stability control system. In addition,
installing any stereo loudspeakers may
interfere with and adversely affect the
electronic stability control system. Install
any aftermarket stereo loudspeaker as
far as possible from the front center
console, the tunnel, and the front seats
in order to minimize the risk of interfering
with the electronic stability control
sensors. Reducing the effectiveness of
the electronic stability control system
could lead to an increased risk of loss of
vehicle control, vehicle rollover, personal
injury and death. WARNING:
Remember that even
advanced technology cannot defy the
laws of physics. It's always possible to
lose control of a vehicle due to
inappropriate driver input for the
conditions. Aggressive driving on any
road condition can cause you to lose
control of your vehicle increasing the risk
of personal injury or property damage.
Activation of the electronic stability
control system is an indication that at
least some of the tires have exceeded
their ability to grip the road; this could reduce the operator's ability to control
the vehicle potentially resulting in a loss
of vehicle control, vehicle rollover,
personal injury and death. If your
electronic stability control system
activates, SLOW DOWN.
The system turns on each time you switch
the ignition on.
If a fault occurs in either the stability
control or the traction control system, the
following conditions are possible:
• The stability and traction control light
illuminate.
• The stability control and traction
control systems are not maintaining
traction of the wheels.
If a driving condition activates either the
stability control or the traction control
system, the following conditions are
possible:
• The stability and traction control light
flash.
• Your vehicle slows down.
• The system reduces engine power.
• A vibration in the brake pedal.
• The brake pedal is stiffer than usual.
• If the driving condition is severe and
your foot is not on the brake, the brake
pedal could move as the system
applies higher brake force.
The stability control system has several
features built into it to help you maintain
control of your vehicle:
Electronic Stability Control
The system assists in preventing skids or
lateral slides by applying the brakes to one
or more of the wheels individually and, if
necessary, decreases engine power.
144
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing Stability Control
(If Equipped)

Traction Control
The system helps maintain traction of the
wheels by detecting and controlling wheel
spin. See Using Traction Control (page
142). Vehicle without stability control
skidding off its intended route.
A
Vehicle with stability control
maintaining control on a slippery
surface.
B
PRINCIPLE OF OPERATION -
VEHICLES WITH: AIR BRAKES WARNING:
Vehicle modifications
involving braking system, aftermarket
roof racks, suspension, steering system,
tire construction and wheel and tire size
may change the handling characteristics
of your vehicle and may adversely affect
the performance of the electronic
stability control system. In addition, installing any stereo loudspeakers may
interfere with and adversely affect the
electronic stability control system. Install
any aftermarket stereo loudspeaker as
far as possible from the front center
console, the tunnel, and the front seats
in order to minimize the risk of interfering
with the electronic stability control
sensors. Reducing the effectiveness of
the electronic stability control system
could lead to an increased risk of loss of
vehicle control, vehicle rollover, personal
injury and death.
WARNING:
Remember that even
advanced technology cannot defy the
laws of physics. It's always possible to
lose control of a vehicle due to
inappropriate driver input for the
conditions. Aggressive driving on any
road condition can cause you to lose
control of your vehicle increasing the risk
of personal injury or property damage.
Activation of the electronic stability
control system is an indication that at
least some of the tires have exceeded
their ability to grip the road; this could
reduce the operator's ability to control
the vehicle potentially resulting in a loss
of vehicle control, vehicle rollover,
personal injury and death. If your
electronic stability control system
activates, SLOW DOWN.
The system automatically turns on each
time you switch the ignition on.
If a fault occurs in either the stability
control or the traction control system, you
may experience the following conditions:
• The stability and traction control light
illuminates steadily.
145
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing Stability Control
(If Equipped)E72903A
AA
B
BB
B

•
The stability control and traction
control systems do not enhance your
vehicle's ability to maintain traction of
the wheels.
If a driving condition activates either the
stability control or the traction control
system you may experience the following
conditions:
• The stability and traction control light
flashes rapidly.
• Your vehicle slows down.
• Reduced engine power.
The stability control system has several
features built into it to help you maintain
control of your vehicle:
Electronic Stability Control
The system enhances your vehicle ’s ability
to prevent skids or lateral slides by
applying brakes to one or more of the
wheels individually and, if necessary,
reducing engine power.
Roll Stability Control
The system enhances your vehicle ’s ability
to prevent rollovers by detecting your
vehicle ’s motion and the rate at which it
changes by applying the brakes to one or
more wheels individually.
Traction Control
The system enhances your vehicle ’s ability
to maintain traction of the wheels by
detecting and controlling wheel spin. See
Using Traction Control (page 142). Vehicle without stability control
skidding off its intended route.
A
Vehicle with stability control
maintaining control on a slippery
surface.
B
USING STABILITY CONTROL
(IF
EQUIPPED)
The system automatically turns on each
time you switch the ignition on.
You cannot switch the stability control and
roll stability control systems off, but when
you shift into reverse (R), the systems
deactivate.
You can switch the traction control system
off or on. See Traction Control (page 142).
Limitations of the Stability System
Stability Control effectiveness may be
greatly reduced if:
146
F650750 (TBC) , enUSA, Edition date: 202010, Second-Printing Stability Control
(If Equipped)E72903A
AA
B
BB
B