BENDIX® ANTILOCK
BRAKING SYSTEM (ABS)
OPERATOR’S MANUAL

Important Safety Information
Bendix safety technologies complement safe driving practices. No
commercial vehicle safety technology replaces a skilled, alert driver
exercising safe driving techniques and proactive, comprehensive driver
training. Responsibility for the safe operation of the vehicle remains with
the driver at all times.
Bendix®-brand Electronic Control Units (ECUs) are not designed to store
data for purposes of accident reconstruction, and Bendix® ACom® PRO™
Diagnostic Software is not intended to retrieve data for purposes of
accident reconstruction. Bendix makes no representations as to the
accuracy of data or video retrieved and interpreted from ECUs for purposes
of accident reconstruction. Bendix does not offer accident reconstruction
services or interpretation of stored data. Bendix ECUs are not protected
from fire, loss of power, impact damage, or other conditions that may be
sustained in a crash situation and may cause data to be unavailable or
irretrievable.

2

Mandate for Electronic Stability Control (ESC)
Federal Motor Vehicle Safety Standard (FMVSS) - 136 Requirements
FMVSS-136 requires the installation of an Electronic Stability Control (ESC) system
on vehicles as described below:
• August 1, 2017 - All “typical” 3 axle 6 x 4 tractors
> Front Gross Axle Weight Rating (GAWR) < 14,600 lbs
> Combined Rear GAWR < 45,000 lbs
• June 24, 2018 - Coaches/buses over 33,000 lbs GVWR
• August 1, 2019 - All other tractors, coaches/buses between 26,000 lbs. and
33,000 lbs. GVWR (includes 4 x 2; 6 x 2; and heavy haul).
Certain exclusions exist to the FMVSS-136 requirement. Contact the vehicle
manufacturer or consult FMVSS-136 for details.
FMVSS-136 requires the addition of a dash lamp to indicate the status of the
ESC system only. This lamp cannot be used to report the state of the Automatic
Traction Control (ATC) system. See your vehicle’s owner manual or contact the vehicle
manufacturer for details on the ESC dash lamp.
FMVSS-136 requires that ESC functionality must be available at speeds of 12.4 mph
(20 kph) and above. Accordingly, in FMVSS-136 compliant Electronic Control Units
(ECUs), the Antilock Braking System (ABS) off-road operation has been modified.
ECU Type

ESC Operation

Non FMVSS-136 Compliant

ESC Disabled Below 25 mph (40.2 kph)

FMVSS-136 Compliant

ESC Disabled Below 11 mph (17.7 kph)

The Bendix® EC-80™ ECUs for the Bendix® Electronic Stability Program (ESP®) system
can be programmed by the vehicle OEM to comply with FMVSS-136. Contact the
vehicle OEM or Bendix for details. The Bendix ESP is an ESC system.

3

Understanding Bendix® Antilock Braking
Systems (ABS) for Air-braked Vehicles
What Is an Antilock Braking System (ABS)?
An ABS system is an electronic control system that improves vehicle stability and
steerability by preventing wheel lock during braking.
How Does the Bendix® ABS System Work?
The Bendix ABS system monitors wheel rotation, and if it detects any wheel locking
up, the system automatically reduces the brake pressure at that wheel. If necessary,
the ABS system automatically modulates braking forces at one (1) or more of the wheel
ends. The system maintains lateral stability by preventing wheel lock during braking.
What is the Optional Bendix ABS Off-road Mode?
This is an optional Bendix ABS feature operated by a dash-mounted switch for use
when operating a vehicle “off road” on soft surfaces. Below 25 mph (40.2 kph) for
non-FMVSS-136-compliant vehicles or 11 mph (17.7 kph) for FMVSS-136-compliant
vehicles, this feature improves ABS performance under off-road operating conditions.
If your vehicle is equipped with this feature, toggle the switch to the ABS Off-road
position when operating on soft surfaces. Always remember to turn off the Bendix
ABS Off-road feature when driving on a firm road surface. A new ignition cycle, or
a second depression of the off-road switch, will turn this function off and restore
normal ABS functionality and – if installed – full Bendix® Electronic Stability Program
(ESP®) system functionality. For more details on optional Bendix Automatic Traction
Control (ATC) and ESP system features, see Pages 7 and 8 of this manual.

The Bendix ABS system off-road mode should not be used on normal, paved
road surfaces because vehicle stability and steerability may be reduced. The
ABS indicator lamp will flash slowly to indicate to the driver that the ABS offroad mode is engaged.

When the Bendix ABS system off-road mode is engaged, stability functions
are disabled at speeds below 25 mph (40.2 kph) for non-FMVSS-136-compliant
vehicles or 11 mph (17.7 kph) for FMVSS-136-compliant vehicles. The Bendix
ATC/ESP system indicator lamp will illuminate to indicate that the stability
systems are disabled.

4

Important Safety Information About
Bendix® Antilock Braking Systems (ABS)
Braking with the Bendix® Antilock Braking System (ABS)
• Do not pump your brakes. Use steady, even brake applications. Apply the
brake pedal with the same pressure as you would without ABS. If you are
towing a vehicle that is not equipped with ABS, you may need to adjust
your braking applications in some instances. See below.
• D o not attempt to modulate your brake applications to prevent
wheel lock. The system controls braking pressure automatically, and
independently, at each wheel end to prevent wheel lock-up.
Limitations of the Bendix ABS System
• The Bendix ABS system does not apply the brakes automatically. It is
still up to you to apply the brakes at the right time and with the right amount
of pedal force. A basic ABS system only starts to do its job after you apply
the brake pedal. NOTE: The Bendix® Electronic Stability Program (ESP®)
system (if equipped on your vehicle) can reduce the throttle and may apply
some or all of the brakes selectively to maintain vehicle stability. See Page 8.
• The Bendix ABS system is not a substitute for safe driving. Even with
the Bendix ABS system, you must remain alert, react appropriately and
in a timely manner, and drive defensively. Do not take unnecessary risks.
Cautious driving practices, such as maintaining an adequate distance away
from the vehicle ahead, not speeding, anticipating obstacles and adjusting
your vehicle’s speed for traffic, weather, and road conditions, are essential
for safe operation.

If replacement tires are used that are a different diameter from the OEM-specified
tire size, the new tire size must be programmed into the ABS controller using
the Bendix® ACom® PRO™ Diagnostic Software.
Towed Vehicles Without ABS
Some towed vehicles, especially older trailers built before 2001, may not be
equipped with their own ABS systems. Use extra care when towing a vehicle that
is not equipped with its own ABS system. During emergency braking or braking on
slippery surfaces, a non-ABS equipped trailer could lose its lateral stability and swing
out if its wheels lock up. Use your mirrors to watch carefully and adjust your brake
applications as necessary to keep your tractor and the non-ABS-equipped towed
vehicle in line with each other. Tractor ABS helps reduce the tendency to jackknife,
but it cannot prevent a non-ABS equipped trailer from swinging out.
5

Understanding the Bendix® Automatic Traction
Control (ATC) System (If Equipped)
What is the Bendix® Automatic Traction Control (ATC) System?
The Bendix ATC system is an optional feature for vehicles equipped with a Bendix®
Antilock Braking System (ABS) that controls wheel spin during vehicle acceleration
to improve traction.
• The Bendix ATC system will intervene automatically and apply braking
pressure to a spinning wheel, thus transferring engine power to other drive
wheels that have better traction. This feature is active only at speeds below
25 mph (40.2 kph).
• If all of the drive wheels begin to spin, the Bendix ATC system will reduce
engine throttle to improve traction at all of the drive wheels.
How Do I Operate a Vehicle with the Bendix ATC System?
If the drive wheels begin to lose traction during acceleration, the ATC system will
engage automatically to assist the driver in accelerating the vehicle.
For non-FMVSS-136-compliant vehicles, the ATC/Bendix® Electronic Stability Program
(ESP®) indicator lamp will flash rapidly to let you know whenever ATC is actively
functioning. For FMVSS-136-compliant vehicles, the ATC indicator lamp will flash
rapidly to let you know whenever ATC is actively functioning.
NOTE: For vehicles equipped with an inter-axle differential lock switch, you should
consult the vehicle Operator’s Manual for additional information about that feature.
Typically, the driver is advised to stop the wheels from spinning and engage the interaxle differential lock switch, but you should always follow the specific instructions
given in your vehicle’s Operator’s Manual for this feature and your vehicle’s particular
configuration.

6

What is Traction Control Override?
Traction Control Override is an optional feature that is operated by a switch on the
dash. When enabled, the Bendix® Automatic Traction Control (ATC) indicator lamp
remains on to indicate that the ATC system has been turned off.
What is the Mud/Snow Mode?
The Mud/Snow mode is an optional ATC feature operated by a dash-mounted
switch. This function allows greater engine power and more wheel spin during
ATC operation. On vehicles equipped with this feature, depress the switch to the
Mud/Snow position when operating on soft road surfaces. The ATC indicator lamp
will flash slowly (every 2.5 seconds) to show that you are in the Mud/Snow mode.
Whenever the ATC system intervenes, the ATC indicator lamp will flash quickly (2.5
times per second). Always remember to turn the Mud/Snow feature off when driving
on a firm road surface. A new ignition cycle, or a second depression of the Mud/Snow
switch, will turn this function off.
What is Bendix® SMART ATC System?
The Bendix SMART ATC system monitors the accelerator pedal position to help
provide optimum traction and vehicle stability. By determining the driver’s throttle
input and adapting the drive wheel behavior to the driving situation, the Bendix
SMART ATC system allows higher wheel slip when the accelerator pedal is applied
above a preset level. In addition, the wheel slip allowed by the Bendix SMART ATC
system is decreased when driving through a curve for improved stability.

7

Understanding the Bendix®
Electronic Stability Program (ESP®) System
What is the Bendix® Electronic Stability Program (ESP®) System?
The Bendix ESP system is an optional feature for vehicles equipped with a Bendix®
Antilock Braking System (ABS) that reduces the risk of rollovers, jackknifing and other
loss-of-control situations. The Bendix ESP system features include roll stability control
and yaw control. NOTE: This feature is optional for all non-FMVSS-136-compliant
vehicles. See Page 4 for more details.

Roll Stability Control
What Is Roll Stability Control (RSC)?
Roll Stability Control (RSC) is a feature on the Bendix ESP full stability systemequipped vehicles that reduces the risk of rollovers.
How Does RSC Improve Vehicle Roll Stability?
RSC counteracts the tendency of a vehicle, or vehicle combination, to tip over while
changing direction (typically, while turning). The lateral forces during a turn can
push a truck or tractor-trailer horizontally and, if the friction between the tires and
the road is sufficient, the vehicle may begin to tip and potentially could roll over.
To reduce the risk of rollover, RSC detects potential rollover conditions and slows
the vehicle both by reducing engine throttle (and hence, engine torque) and by
applying the tractor and trailer service brakes as needed at the appropriate wheels.

During an RSC intervention, the vehicle automatically decelerates. The system
can slow the vehicle with or without you applying the brake pedal, and even
when you are applying the throttle.

8

During a Roll Stability Control (RSC) intervention, you can always use your service
brake pedal to increase the braking pressure that will be applied. However, if you
were to apply less braking pressure than needed – or even if you release the brake
pedal entirely during an intervention – the system will continue to apply the necessary
amount of braking pressure automatically to the appropriate wheels to mitigate a
potential rollover.
Driving Scenario: A vehicle enters a curve too
fast, on high-friction pavement, resulting in high
lateral (side) forces acting at the vehicles center of
gravity (CG). The high friction between the wheels
and the pavement create a “hinge” effect allowing
the forces at theA
CG to push the vehicle over.

RSC Intervention: The roll stability control
automatically reduces engine torque and applies
the service brakes (based on the projected rollover
risk) to reduce the vehicle speed, thereby reducing
the tendency to roll over.

AA

A
B

B

B

C

C
C

A: Tractor/Trailer

B: Transit Bus

9

C: School Bus

C

Yaw Control
What Is Yaw Control?
Yaw control is a feature on vehicles equipped with the Bendix® Electronic Stability
Program (ESP®) system that reduces the risk of jackknifing and other loss-of-control
situations. If a vehicle’s tires start to slide during a turn, yaw control counteracts the
tendency of that vehicle to spin (or “yaw”), thereby reducing the risk of a jackknife
or other loss-of-control situations. Many factors – including road conditions, load
distribution, and driving behavior – can contribute to the development of a spin.
Spins occur where either: (a) the rear wheels begin to lose their grip on the
road – which could lead to a jackknife when towing a trailer; or, (b) the front wheels
begin to lose their grip, reducing a vehicle’s ability to respond to the driver’s steering
inputs.
Yaw control continually monitors the direction in which you are steering the vehicle as
well as the vehicle’s response to those steering inputs. If the system detects that the
vehicle is beginning to spin, yaw control reduces the engine throttle, uses selective
braking at the four (4) corners of the vehicle – and may also use trailer braking – to
help you keep the vehicle under control.

During a yaw control intervention, the vehicle automatically decelerates. Yaw
control can slow the vehicle with or without you applying the brake, and even
when you are applying the throttle.
Driving Scenario: Excessive speed exceeds the
threshold, creating a situation where a vehicle is
likely to spin and jackknife.

A

A

B

C

Yaw Control Intervention: The yaw control
feature reduces engine throttle and selectively
applies brakes to reduce the tendency to jackknife.

B

B

A

AB
C

B

A

B

C

C

C
A: Tractor/Trailer

B: Transit Bus
10

C: School Bus

Important Safety Information About the Bendix®
Electronic Stability Program (ESP®) System
The Bendix® Electronic Stability Program (ESP®) system may reduce your
speed automatically. The Bendix ESP system can make your vehicle decelerate
automatically. The Bendix ESP system can slow the vehicle with or without you
applying the brake, and even when you are applying the throttle.
To minimize unexpected deceleration and reduce the risk of a collision:
• Avoid aggressive driving maneuvers – such as sharp turns or abrupt lane
changes at high speeds – which might trigger the stability system.
• Always operate your vehicle safely, drive defensively, anticipate obstacles
and pay attention to road, weather, and traffic conditions. Bendix® Antilock
Braking System (ABS), Automatic Traction Control (ATC), and ESP systems are
no substitute for prudent, careful driving.
Limitations of the Stability System
The Bendix ESP system’s effectiveness may be greatly reduced if:
• Your load shifts due to improper retention, accident damage or the
inherently mobile nature of some loads (i.e. hanging meat, live animals, or
partially laden tankers);
• Your vehicle or load has an unusually high or offset Center of Gravity (CG);
• Your brakes are not properly adjusted or maintained; or
• One side of your vehicle drops off the pavement at an angle that is too great
to be counteracted by a reduction in speed.
To Maximize the Effectiveness of a Bendix ESP System:
• Make sure that the weight of your load is evenly distributed – front to back
and side to side – and is properly secured at all times.
• Exercise extreme caution at all times while driving. Avoid sharp turns, sudden
steering inputs, or abrupt lane changes at high speeds, particularly if:
• you haul loads that could shift;
• your vehicle or load has a high – or offset – CG when loaded; or
• you are towing double or triple trailers.

11

Chassis Modifications
The Bendix® Electronic Stability Program (ESP®) system is specifically calibrated
and validated only for your vehicle’s original configuration. If the vehicle’s chassis
components are altered (for example, a wheel base extension or reduction; tag axle
addition or removal; a major body change such as conversion of a tractor into a truck;
or an axle, suspension, or steering system component modification), the ESP Electronic
Control Unit (ECU) must be updated to reflect these changes. Contact your OEM prior
to making any modifications to your vehicle.

If you modify your vehicle and do not update the ESP ECU, the ESP system may fail
to function as intended. Serious vehicle braking and performance issues could
result, including unnecessary ESP system interventions, exceeding regulated
stopping distance, and/or system faults leading to loss of system functions.
These types of failures can lead to loss-of-control of the vehicle and/or collisions
causing property damage, serious injuries, or death.
Steering Angle Sensor Recalibration
Whenever maintenance or repair work is performed – to the steering mechanism,
linkage, steering gear, adjustment of the wheel track, or if the steering angle sensor is
replaced – a recalibration of the steering angle sensor must be performed.

If the steering angle sensor is not recalibrated, the yaw control system will not
function properly, which could result in loss of control of your vehicle.

When replacing a steering wheel, use only a vehicle manufacturer approved
steering wheel and be sure that the steering angle sensor is not damaged during
installation. Recalibrate the steering angle sensor.

If replacement tires are used that are a different diameter from the OEM-specified
tire size, the new tire must be programmed into the Bendix® Antilock Braking
System (ABS) controller using Bendix® ACom® PRO™ Diagnostic Software.

The location and orientation of the yaw rate sensor must not be altered. When
servicing, an identical component must be used in the same orientation (using
OEM brackets and torque requirements). During installation, follow the OEM
leveling guidelines.
12

Understanding the Bendix® Antilock
Braking System (ABS) Indicator Lamps
(Non-FMVSS-136-compliant Vehicles)

Bendix® Antilock Braking System (ABS) Indicator Lamp
An amber ABS indicator lamp is typically located on the dashboard.
• At each vehicle ignition your ABS indicator lamp should illuminate as a bulb
check for approximately three (3) seconds and then turn off. If the lamp
does not illuminate at ignition, you should have the vehicle serviced by
a qualified mechanic as soon as possible. NOTE: Without a functioning
indicator lamp, you may not be able to determine the ABS status without
using an external diagnostic tool.
• If the indicator lamp remains on for more than three (3) seconds after
ignition, or if it illuminates while you are driving, the ABS system may not
be fully functional or may be completely disabled. If the ABS is completely
disabled or not functioning properly, your vehicle will still have normal
service braking and it still can be driven, although without the benefits
of ABS. Have the vehicle serviced by a qualified mechanic as soon as
possible to restore full ABS functionality.
• The ABS indicator lamp is also used to indicate the optional off-road ABS
mode. The lamp will flash continually when the vehicle is operating in the
off-road mode. NOTE: When the ABS off-road mode is engaged, stability
functions are disabled at speeds below 25 mph (40.2 kph). The Automatic
Traction Control (ATC)/Bendix® Electronic Stability Program (ESP®) indicator
lamp will illuminate to indicate that the stability systems are disabled.) See
Page 4 of this manual for additional sources of information about the ABS offroad operating mode.

13

Trailer Bendix® Antilock Braking System (ABS) Indicator Lamp
The trailer ABS indicator lamp is also dash-mounted.
• All trailers built since March 2001 are able to communicate with the towing
vehicle and operate the trailer ABS indicator lamp on the towing vehicle’s
dash. The trailer ABS indicator lamp functions just like the tractor ABS
indicator lamp. It is illuminated for three (3) seconds after each vehicle
ignition, then extinguished – unless a problem develops with the trailer
ABS during operation.
• All new trailers built since March 1, 2009, are equipped with an amber ABS
indicator lamp located near the rear of the trailer on the driver’s side. The
operation of the lamp varies depending on how the ABS system is powered:
a. For full-time-powered ABS (usually obtaining power over the
blue line of the J560 connector): The trailer ABS indicator lamp
will function just like the tractor ABS indicator lamp, listed above.
b. For brake-light-only powered ABS: Each time the brakes are
applied, the indicator lamp will illuminate for approximately three
(3) seconds and then turn off. If the indicator lamp remains on
during braking, the trailer’s ABS may not be operating. The trailer