­­­Technical Bulletin
Bulletin No: TCH-11-003 Rev 001
Subject:

Initial Release Date: August 1, 2023 Revision Date: May 20, 2024

Page: 1 of 8

Bendix® 600-volt Electric Screw Module 1 (ESM1)

OVERVIEW
The Bendix® Electric Screw Module 1 (ESM1) is an electric air compressor that generates and supplies compressed air
for a commercial vehicle air brake system. The major components that constitute the ESM1 assembly are the high-voltage
electric motor (E-motor) (with an integrated inverter and CAN interface) and the oil-injected rotary screw compressor. Using
electrical energy from the batteries of the Electric Vehicle (EV), the electric motor drives the compressor using a flange
coupling connection between the two (2) sub-components to produce compressed air. See Figure 1.
The ESM1 is a high-voltage, liquid-cooled device, and requires coolant from the vehicle’s cooling circuit during operation.
The coolant runs in series – first through the motor and then through the heat exchanger on the compressor. The compressor
has a self-contained oil system and does not require oil fed from the vehicle during operation. The ESM1 is required to
be physically protected from wind and road splash using an enclosure box and/or thermal insulation for proper thermal
management of the device.

Water-cooled
Flange

Coolant
In Port

Air Inlet

High-Voltage E-motor
with Integrated Inverter

Air Filter Housing
Identification
Nameplate

Sensor Wiring
Harness

Compressed
Air Outlet

Oil-coalescing
Filter

Rubber
Coolant Hose

Coolant
Out Port

Coupling

18 Bar
Safety Valve
Lifting Eyes
Oil Level
Sensor/Switch
Rotary Screw
Compressor

Oil Level
Port

Low-Voltage
Vehicle Wiring
Connector

Oil Fill Port
Rotary Screw
Compressor
High-Voltage
Power Connector
(Amphenol)

Oil Temperature
Sensor/Switch

Figure 1 – Electric Screw Module 1 (ESM1) Components

Service of the high-voltage system on this vehicle is restricted to qualified personnel. The required qualifications
vary by region. Always observe local laws and legislative directives regarding electric vehicle service. Failure to
follow this instruction may result in serious personal injury or death.

Persons with active implants must not work on the high-voltage system. The high-voltage system generates electric
and magnetic fields. Fatal or serious physical injury can ensue from malfunctioning active implants (e.g., heart
pacemaker, insulin pumps). Failure to follow these instructions may result in serious personal injury or death.

To prevent the risk of high-voltage shock, always precisely follow all warnings and service instructions including
instructions to depower the system. The high-voltage system utilizes high-voltage cables to its components and
modules. The high-voltage cables and wiring are identified by orange harness tape or orange wire covering. All
high-voltage components are marked with high-voltage warning labels with a high-voltage symbol. Failure to follow
these instructions may result in serious personal injury or death.

Disconnect the 12 V (or 24 V) battery before servicing the direct current to alternating current (DC-AC) inverter or
alternating current (AC) power point to prevent the risk of high-voltage shock. Failure to follow this instruction may
result in serious personal injury.

Extreme heat, such as paint-drying ovens, will cause damage of the high-voltage battery. The high-voltage battery
must be removed before using paint-drying ovens longer than 45 minutes or with temperatures above 140°F (60°C).
Failure to follow this instruction may result in damaging the high-voltage battery, which could cause serious personal
injury or death in a fire or explosion.

FOR VEHICLES EQUIPPED WITH A SERVICE DISCONNECT PLUG: Never install the service disconnect plug when
a high-voltage service cover is removed. Always install the cover prior to connecting the service disconnect plug.
The cover prevents inadvertent contact with the high voltage, which is present at several points under the cover.
Failure to follow these instructions may result in serious personal injury or death.

Work on high-voltage components during live-voltage conditions requires an additional person present to ensure
safety. This person must be a qualified High-Voltage Technician equipped with a rescue hook and able to provide
first aid in case of electrical shock. Failure to follow these instructions is a violation of European legislation safety
regulations and may result in serious personal injury or death.

The Bendix® Electric Screw Module 1 (ESM1) is a high-voltage device. Beware of electric shock. Service for the ESM1 must
be performed only by qualified technicians. The ESM1 has a high-voltage motor, and the motor should not be opened or
dismantled for repair. The ESM1 has air under high pressure within the rotary screw compressor, and care must be taken when
servicing the compressor to avoid sudden air pressure loss and/or hot oil expulsion, which could result in injury or death.

IMPORTANT
The ESM1 has one (1) integral lifting eye on the compressor (18-mm diameter) and two (2) side M8 tapped holes on
the motor that allow lifting eyes to be screwed onto the device. Care should be taken to not tilt the ESM1 more than
45º during handling and installation to prevent oil spill.

MAINTENANCE
Maintenance must be performed every 1,500 operating hours (operating hours are defined as when the compressor is
running) or at least once a year.
• Change the oil (Chevron® Cetus® PAO 46 or
Castrol® Alphasyn T46 only)
•

Replace the oil-coalescing filter

•

Replace the air filter

• Visually check the compressor to track any potential
issues (leakages, shocks, etc.)

AIR AND COOLANT CONNECTIONS
See Figure 2 for the air and coolant connections for the Bendix® Electric Screw Module 1 (ESM1).
AIR INLET

AIR OUTLET

COOLING WATER IN

COOLING WATER OUT

Figure 2 – Air and Coolant Connections

ELECTRICAL CONNECTION
See Figure 3 for the low- and high-voltage connections for the Bendix® Electric Screw Module 1 (ESM1).
LOW-VOLTAGE VEHICLE WIRING CONNECTOR (TE)
TE Connectivity 1-1564520-1

HIGH-VOLTAGE POWER CONNECTOR (AMPHENOL)
Amphenol C91-665341-AFS

1

+24V

A

+600V

2

15_Wake_up

B

HVIL

3

Enable

C

-600V

4

CAN_Shield

D

HVIL

5

GND

6

Secondary_Wake_up

7

CAN H

8

CAN L

9

+24V for Heater

10

GND for Heater

11

Plugged

12

Plugged

Figure 3 – Low- and High-Voltage Connections

SHIELD

DIAGNOSTIC TROUBLE CODES (DTCS)
Use Bendix® ACom® PRO™ Diagnostic Software to read any potential Diagnostic Trouble Codes (DTCs) on the Bendix®
Electric Screw Module 1 (ESM1), and take the appropriate next steps. Refer to Table 1.

DTC CODE
(DEC)

257

258

259

260

DM1 AMBER
WARNING
LAMP

No

No

No

No

DM1 RED
WARNING
LAMP

Yes

No

No

Yes

Table 1 – Diagnostic Trouble Codes (DTCs)

NAME

DESCRIPTION

eCompressor
(ESM1) fault:
Traction voltage
critically low, motor
stopped

DC traction high-voltage
supply malfunction: Voltage
lower than 420 V for 5
seconds, and the ESM1 is
requested to run.

eCompressor
(ESM1) fault:
Traction voltage low,
reduced speed

DC traction high-voltage
supply malfunction: Voltage
lower than 500 V for 5
seconds, and the ESM1 speed
is below 81% of requested
speed for 5 seconds.

eCompressor
(ESM1) fault:
Allowable current
limit reached

eCompressor
(ESM1) fault:
Traction voltage
critically high, motor
stopped

DTC ACTION

•

The voltage being supplied to the ESM1
is outside of the nominal range of 500800 VDC. Contact the OEM for further
troubleshooting on the ESM1 highvoltage power supply.

•

If the voltage is found to be within the
nominal range of 500-800 VDC, and the
DTC persists, replace the ESM1 motor.

•

The voltage being supplied to the ESM1
is outside of the nominal range of 500800 VDC. Contact the OEM for further
troubleshooting on the ESM1 highvoltage power supply.

•

If the voltage is found to be within the
nominal range of 500-800 VDC, and the
DTC persists, replace the ESM1 motor.

•

Check the compressor air discharge
line for potential blocks due to ice or
other reasons, and clear any blockage if
present. Ensure there is free air flow to
the air dryer.

•

If no blockage is found, check the oil
level in the compressor through the side
level port. CAUTION: Unscrewing the
oil plug may result in air pressure loss
or hot oil spurting. Ensure there is no
air pressure within the compressor by
unscrewing for a half turn and letting the
system de-pressurize before unscrewing
completely. Refill if oil is needed.

•

If the previous steps do not resolve the
Diagnostic Trouble Code (DTC), contact
the OEM to verify that the allowable
current limit for the unit is > 15A, as
controlled by the vehicle controller.

•

If the problem persists, the issue could
be a damaged motor or a damaged
compressor; replace the damaged
component.

•

The voltage being supplied to the ESM1
is outside of the nominal range of 500800 VDC. Contact the OEM for further
troubleshooting on the ESM1 highvoltage power supply.

•

If the voltage is found to be within the
nominal range of 500-800 VDC, and the
DTC persists, replace the ESM1 motor.

Motor allowable current limit
reached in high-voltage line.

DC traction high-voltage
supply malfunction: Greater
than 800V for 0.5 seconds,
and the ESM1 is requested
to run.

DTC CODE
(DEC)

261

DM1 AMBER
WARNING
LAMP

No

DM1 RED
WARNING
LAMP

Yes

NAME

eCompressor
(ESM1) fault: Motor
overload

DESCRIPTION

DTC ACTION

•

Check the compressor air discharge
line for potential blocks due to ice or
other reasons, and clear any blockage if
present. Ensure there is free air flow to
the air dryer.

•

If no blockage is found, check the oil
level in the compressor through the side
level port. CAUTION: Unscrewing the
oil plug may result in air pressure loss
or hot oil spurting. Ensure there is no
air pressure within the compressor by
unscrewing for a half turn and letting the
system de-pressurize before unscrewing
completely. Refill if oil is needed.

•

If the previous steps do not resolve the
Diagnostic Trouble Code (DTC), the
issue could be a damaged motor or
a damaged compressor; replace the
damaged component.

Motor overload, failed to
achieve >1400 RPM for 15
seconds continuously.

262

No

Yes

eCompressor
(ESM1) fault: Motor
internal fault

Motor internal fault - Power
stage error.

•

Replace the ESM1 motor.

263

No

Yes

eCompressor
(ESM1) fault: Motor
internal fault

Motor internal fault - No
connection with power unit.

•

Replace the ESM1 motor.

•

Turn off the device and allow the ESM1
to cool down for approximately 60
minutes.

•

Ensure that there is proper coolant
supply to the ESM1. Coolant must be
50-50 ethylene glycol-water mixture at
nominal temperature of 40ºC (104ºF)
(should not go below 30ºC [86ºF] or
above 65ºC [149ºF]), with flow rate
of 10 l/min. Contact the OEM if the
coolant flow or temperature is not within
specification.

•

Check the sensor wiring harness