SD-24-2936
Bendix® Standalone Electronic Air Control (SA-EAC) System
INTRODUCTION
The Standalone Electronic Air Control (SA-EAC) system
is a set of software functions that are integrated into a
standalone version of a Bendix® Electronic Control Unit
(ECU).
The SA-EAC system adds features supporting the Bendix®
AD-HFi® air dryer including J1939 messaging, Diagnostic
Trouble Codes (DTCs), advanced functionality, and
governor control.

DESCRIPTION
The SA-EAC system provides the basic governor operation
to maintain set air pressure levels and provides advanced
features, along with air system diagnostic and prognostic
information.
The SA-EAC system communicates on the vehicle J1939
CAN bus and receives vehicle information including primary
and secondary air pressures, engine speed, torque, and
other vehicle operational conditions. The SA-EAC system
also transmits compressor state, diagnostic, and prognostic
information, such as cartridge lifetime prediction, on the
vehicle CAN bus.

Beyond basic governor control, the SA-EAC system
has advanced features to optimize air system pressure
control and conserve energy. The SA-EAC system also
has advanced purge operations to protect the air system
against moisture.

IMPORTANT
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.

Figure 1 – SA-EAC
1

GENERAL SAFETY GUIDELINES

WARNING! PLEASE READ AND FOLLOW THESE INSTRUCTIONS
TO AVOID PERSONAL INJURY OR DEATH:

When working on or around a vehicle, the following guidelines should be observed AT ALL TIMES:
▲ Park the vehicle on a level surface, apply the ▲ Never connect or disconnect a hose or line
parking brakes, and always block the wheels.
containing pressure; it may whip and/or cause
Always wear personal protection equipment.
hazardous airborne dust and dirt particles. Wear
eye protection. Slowly open connections with
▲ Stop the engine and remove the ignition key
care, and verify that no pressure is present. Never
when working under or around the vehicle.
remove a component or plug unless you are
When working in the engine compartment,
certain all system pressure has been depleted.
the engine should be shut off and the ignition
key should be removed. Where circumstances ▲ Use only genuine Bendix ® brand replacement
require that the engine be in operation, EXTREME
parts, components, and kits. Replacement
CAUTION should be used to prevent personal
hardware, tubing, hose, fittings, wiring, etc.
injury resulting from contact with moving,
must be of equivalent size, type, and strength as
rotating, leaking, heated, or electrically charged
original equipment and be designed specifically
components.
for such applications and systems.
▲ Do not attempt to install, remove, disassemble, ▲ Components with stripped threads or damaged
or assemble a component until you have read,
parts should be replaced rather than repaired.
and thoroughly understand, the recommended
Do not attempt repairs requiring machining or
procedures. Use only the proper tools and
welding unless specifically stated and approved
observe all precautions pertaining to use of those
by the vehicle and component manufacturer.
tools.
▲ Prior to returning the vehicle to service, make
▲ If the work is being performed on the vehicle’s
certain all components and systems are restored
air brake system, or any auxiliary pressurized air
to their proper operating condition.
systems, make certain to drain the air pressure ▲ For vehicles with Automatic Traction Control
from all reservoirs before beginning ANY work
(ATC), the ATC function must be disabled (ATC
on the vehicle. If the vehicle is equipped with
indicator lamp should be ON) prior to performing
®
®
®
a Bendix AD-IS air dryer system, a Bendix
any vehicle maintenance where one or more
™
®
®
DRM dryer reservoir module, a Bendix AD-9si ,
wheels on a drive axle are lifted off the ground
AD-HF®, or AD-HFi® air dryer, be sure to drain the
and moving.
purge reservoir.
▲ The power MUST be temporarily disconnected
▲ F o l l o w i n g t h e v e h i c l e m a n u f a c t u r e r ’s
from the radar sensor whenever any tests USING
recommended procedures, deactivate the
A DYNAMOMETER are conducted on a vehicle
electrical system in a manner that safely removes
equipped with a Bendix® Wingman® system.
all electrical power from the vehicle.
▲ Never exceed manufacturer’s recommended
pressures.
▲ You should consult the vehicle manufacturer's operating and service manuals, and any related literature,
in conjunction with the Guidelines above.

2

Vehicle 12V
Ignition
Power

OE-specified
CAN bus

Connector

Pin Description

Pin 1

OUT_H1 (SOLENOID)

Pin 2

US (POWER/IGN)

Pin 3

NOT USED (GND)

Pin 4

CANL

Pin 5

OUT_L1 (SOLENOID)

Pin 6

GND

Pin 7

NOT USED (GND)

Pin 8

CANH

Figure 2 – SA-EAC System

3

SYSTEM COMPONENTS
The Bendix® Standalone Electronic Air Control (SA-EAC)
system is a set of software functions that are integrated into
the SA-EAC Electronic Control Unit (ECU). See Figure 2.
The SA-EAC is part of the vehicle air supply system, which
consists of the SA-EAC ECU, air dryer, and compressor.
The SA-EAC ECU is uniquely configured for three (3)
system components.

IMPORTANT
If any of these components are replaced, they must
be replaced with genuine OE service parts. Failure
to do so could result in damage to other air system
components.
1. SA-EAC ECU: The ECU that controls the SA-EAC
system will be referred to as the SA-EAC ECU. The
SA-EAC ECU receives air system pressure information
from the vehicle J1939 CAN bus and controls the air
compressor governor to maintain safe air pressure
levels. The SA-EAC ECU monitors the air system
pressure. The unit energizes and de-energizes the
compressor solenoid governor to unload and load
the vehicle air compressor. The SA-EAC ECU also
receives engine speed, torque, and vehicle speed
from the engine Electronic Control Module (ECM)
to provide advanced features. The SA-EAC system
sets Diagnostic Trouble Codes (DTCs) which can
be displayed via Bendix® ACom® PRO™ Diagnostic
Software to evaluate system status.
2. Air Dryer (Bendix ® AD-HFi ® SP Air Dryer and
Bendix® AD-HFi® EP Air Dryer): The air dryer removes
water and other contaminants from the air delivered
from the compressor. The SA-EAC system supports air
dryers with different purge volumes, such as the AD-HFi
SP or AD-HFi EP. The SA-EAC ECU parameters are
specified by the OE to accommodate the appropriate
purge volume. The compressor solenoid governor, part
of the air dryer, is controlled by the SA-EAC ECU to
load and unload the air compressor.
3. Air Compressor: The air compressor delivers
pressurized air to the air dryer and pressurizes the
entire air brake system.

4

SA-EAC SYSTEM DESCRIPTION WITH
BASIC GOVERNOR AND
ADVANCED FEATURES
The SA-EAC system provides basic governor control and
advanced air system control features.

BASIC GOVERNOR CONTROL
The SA-EAC system provides basic governor control that
loads and unloads the compressor as needed to maintain
a safe air system pressure level. When the air pressure
drops below the cut-in pressure threshold, the SA-EAC
system will load the compressor. When the air pressure is
greater than the cut-out pressure threshold, the SA-EAC
system will unload the compressor and purge the air dryer
desiccant to remove moisture.

ADVANCED FEATURES
The SA-EAC system provides advanced air system control
features.
•

Energy Savings: The SA-EAC system monitors the
state of the engine and may take advantage of certain
situations by engaging the compressor and charging
the system, taking advantage of otherwise wasted
energy. This feature may result in slight overcharging
of the service system, not to exceed the OE-specified
cut-out pressure.

•

Performance Enhancements: The SA-EAC system
may operate differently than a traditional pneumatic
charging system. Because the SA-EAC system
can monitor the air system and vehicle use, it may
not always load and unload the compressor at the
same pressures. Additionally, the SA-EAC system
is also capable of monitoring the health of the air
dryer cartridge using available vehicle data. If the
SA-EAC system determines that excessive water is
accumulating in the air dryer cartridge, it may unload
the compressor and initiate a purge. Refer to the
Section titled: Interrupted Charge Regeneration (ICR).
This may happen at a system pressure level lower than
expected. After the interrupted charge is complete,
the system will automatically continue to charge as
normal and will purge again when maximum pressure
is reached.

•

•

Cartridge Lifetime Prediction (CLP): CLP monitors
the vehicle usage conditions and provides an estimate
of the health and remaining life. It also provides
Diagnostic Trouble Codes (DTCs) when the estimated
life falls below certain threshold levels. Bendix® ACom®
PRO™ Diagnostic Software supports the resetting of
the CLP to "100% remaining." Resetting the CLP must
only be done after servicing and replacing the cartridge.
Diagnostics: The Bendix® Standalone Electronic Air
Control (SA-EAC) system includes several different
diagnostic features that can provide DTCs when
abnormal system usage is suspected. This may include
excessive compressor usage or excessive moisture
build-up in the desiccant cartridge or system.

TROUBLESHOOTING
The SA-EAC system normally operates in the basic
governor mode – as described above – loading at cut-in
and unloading (and regeneration) at cut-out air pressures.
If there are fault conditions and/or vehicle or solenoid
governor interface problems, normal operation and
advanced features may be disrupted. In this case, check
for the following abnormal conditions.

hen the primary or secondary air pressure is below
W
cut-in, Pin 1 to the solenoid should be low – or ground
potential voltage – to load the compressor. When the
primary or secondary air pressure is below cut-in,
the electrical potential across Pin 1 and Pin 2 to the
solenoid should be low – or ground potential voltage
– to load the compressor.
hen the primary and secondary air pressures are
W
above cut-out, the electrical potential across Pin 1
and Pin 2 to the solenoid should be high – or positive
potential voltage (nominal 12V) – to unload the
compressor. If attempting to confirm this behavior
from the SA-EAC, a load with 40 ohm resistance (e.g.
a 1157 stop lamp bulb) must be present to check
accurate behavior.
• Invalid primary or secondary pressure signal
on CAN: The primary and secondary pressure
signals are sent to the SA-EAC controller over
CAN, originating from the vehicle system pressure
sensors. During normal operation and when the
service system is above cut-in pressure, these two
(2) pressure signals should be approximately equal.
If the pressure signals differ by more than one (1) bar
(14.7 psi), the SA-EAC system can no longer trust
the signal information and may default to constant
build of air. Check the values of these signals per the
vehicle manufacturer's recommendation and replace
if necessary.

CONSTANT AIR BUILD: In certain fault conditions (e.g.
the solenoid is not working properly or the air dryer is not
properly connected), the SA-EAC fail safe operation is
to constantly load the compressor, building air pressure.
This may result in an activation of the safety valve; refer to
SD-08-12046, Bendix® AD-HF® and AD-HFi® Service Data
Sheet, on B2Bendix.com. Constant air build will occur
if there are compressor solenoid governor connection
problems or missing or invalid vehicle CAN messages or
signals.

• Check the Vehicle J1939 CAN Connection and
Baud Rate: The SA-EAC system requires vehicle
CAN messages and signal information that controls
the compressor. Check the vehicle J1939 CAN
bus connections to the SA-EAC system match the
following connections.

• Unavailable system pressure information: Refer
to the vehicle manufacturer for the CAN diagnostics
process.

The SA-EAC is factory-programmed to operate at a fixed
baud rate. Check to ensure the vehicle CAN and SA-EAC
baud rates match.

J1939 CAN

SA-EAC Pin

CAN_H

Pin 8

CAN_L

Pin 4

• Check the compressor solenoid governor: The
SA-EAC system controls the compressor with a
pneumatic solenoid. Check the connection from the
SA-EAC, molex connector, and Pin 1 and Pin 5 to the
solenoid match the following connections.
SA-EAC Pin

Solenoid Connector Pin

Pin 1

Pin 1

Pin 5

Pin 2

5

UNEXPECTED DIFFERENCE IN CUT-IN
AND CUT-OUT
The Bendix® Standalone Electronic Air Control
(SA-EAC) system has advanced features that will
temporarily adjust the normal cut-in and cut-out pressure
thresholds.
• Overrun (OVR): When there is low engine torque
demand – such as when going downhill – the OVR
feature will temporarily raise the cut-in and cut-out
pressures.
• Overtake (OVT): When there is high engine torque
demand – such as when overtaking/passing – the
OVT feature will temporarily lower the cut-in and cutout pressures.
• Interrupted Charge Regeneration (ICR): When the
air dryer cartridge moisture level begins to approach
oversaturation for a single charge cycle, the ICR
feature will temporarily unload the compressor
to initiate an air dryer purge. After this purge has
completed, the charge cycle will continue again until
cut-out pressure is achieved.
SA-EAC SYSTEM INFORMATION FOR
SERVICE SHOPS
• Loaded Mode: The SA-EAC system stays in loaded
mode, continuously building air; the safety valve will
activate at overpressure.
• Cartridge Monitoring: The SA-EAC system
continues to track air dryer cartridge health and will
report associated Diagnostic Trouble Codes (DTCs).
• Service Shop: The service shop should be aware
that if vehicle conditions put the SA-EAC system into
continuous load operation, the safety valve can be
compromised and the air dryer cartridge can become
saturated. In this case, the service person should
replace the safety valve. The service person should
also check for SA-EAC system mid- and high-level
moisture DTCs. If a high-level DTC exists, the air dryer
cartridge should be replaced. Refer to SD-08-12046,
Bendix ® AD-HF ® and AD-HFi® Service Data Sheet,
on B2Bendix.com.

6

SA-EAC SYSTEM DIAGNOSTIC SUPPORT
DTC DETECTION
The SA-EAC system contains self-testing diagnostic
circuitry that continuously checks for proper operation and
external compressor solenoid governor and wiring.

DTC DESCRIPTION AND REPAIR INFORMATION
The SA-EAC Electronic Control Unit (ECU) DTCs are
supported by Bendix® ACom® PRO™ Diagnostic Software.
Refer to Table 1. Visit B2Bendix.com for additional
information and for downloads of the ACom PRO
Diagnostic Software.
Depending on the version of ACom PRO Diagnostic
Software, it will display the SA-EAC ECU on its roll call
and other relevant screens as "Electronic Air Control
(Standalone)."
DTC STORAGE / EVENT HISTORY
SA-EAC system and ACom PRO Diagnostic Software
retain a record of DTCs. This record is commonly referred
to as "event history." When a DTC self heals or is manually
cleared, the DTC code remains in event history as an
inactive DTC.

BENDIX® STANDALONE ELECTRONIC AIR CONTROL (SA-EAC) ELECTRONIC CONTROL UNIT
(ECU) DIAGNOSTIC TROUBLE CODES (DTCS) AND SERVICE INFORMATION
The SA-EAC does not include any Bendix-specified driver feedback mechanism. Some applications may include dash
or other feedback as determined by the OE. Consult with the OE to interpret any driver feedback.

SPN

FMI

DTC/
Lookup
Code