80 teeth

512 to 801

90 teeth

456 to 711

100 teeth

410 to 640

120 teeth

356 to 502

(in revolutions per mile)

Table 4 – Tone Ring Size to Tire-Rolling Radius

14. DTC DETECTION
The iTABS module contains self-testing diagnostic circuitry
that monitors the ABS components and wiring. When the
iTABS module senses an erroneous system condition, it
activates the external trailer-mounted ABS indicator lamp,
disables all or part of the affected ABS functions, and it
stores the DTC in memory, so that the information is retained
even when the power is removed. The iTABS module also
uses PLC communications to send the system status to the
towing vehicle.
For some DTCs, the iTABS module will automatically reset
(“self-heal”) the active DTC when the error is corrected.
However, repeated occurrences of a given DTC can cause
the code to “latch” – that is, be retained as active – even if
the condition is only intermittent. Once the code is latched,
a manual reset will be necessary. Technicians can use these
latched codes to assist them in troubleshooting intermittent
errors. After the problem is repaired, the DTC can be reset
using blink code diagnostics or with a diagnostic tool. After
a certain number of power cycles to the iTABS module, an
inactive DTC will clear itself automatically from the fault
memory. For more information about this feature, contact
your local Bendix representative.

10

ECU DTCS

VOLTAGE DTCS
The operating voltage range is 9.0-16.0 VDC. If the voltage
is detected as being out of range, the ABS system braking
features will be disabled, and the system will revert to normal
braking. When the correct voltage level is restored, full ABS
is typically available again.

16. BLINK CODE DIAGNOSTICS

DISPLAY ACTIVE DTCS

The iTABS module provides diagnostic functions through
blink code diagnostics. This means that the technician – even
without diagnostic tools – can read a series of ABS indicator
lamp blinks to diagnose the DTCs being generated.

To display active DTCs, apply ignition power and depress
and release the brake pedal three (3) times within 15
seconds (allowing one [1] second between each application).
Following this activation, there will be a five (5) second delay
followed by a blink code display sequence of all active DTCs.

With no towing vehicle attached, the technician may enter
the blink code diagnostics mode by providing constant power
to the ignition circuit and then select the desired mode by
toggling the brake light power input the specific number of
times shown in Table 5.
With a parked towing vehicle attached, apply ignition power,
and after the power-up sequence is complete, enter the
diagnostics mode by depressing and releasing the brake
pedal the specific number of times shown in Table 5 for the
desired mode.

Cycles

Active DTC Retrieval

3

Inactive DTC Retrieval (DTC History)

4

Clear Active DTCs

5

Odometer Mileage Display

7

Table 5 – Blink Code Information
Depending on the blink code mode activated, the iTABS
module will blink the trailer-mounted ABS indicator lamp to
display active DTCs, inactive DTCs, and odometer mileage.
Blink code diagnostics can also be used to clear active DTCs.
Wait until after the modulator chuff test before activating the
brake light power. Alternatively, wait five (5) seconds.
NOTE: If certain DTCs are active, typically where modulator
DTCs have occurred, the chuff test may not run.
Following a single display of all available messages, the ABS
indicator lamp will remain on for five (5) seconds and then
return to normal operating mode. Blink code diagnostics can
only be activated following a power-up, where wheel speeds
have not been detected. If the vehicle moves during the blink
code diagnostics mode, the iTABS module will cancel the
blink code diagnostics and return to normal operating mode.
Blink code diagnostics must be activated within the first 15
seconds of ignition power being applied.
If brake light power is continuously applied for more than five
(5) seconds, blink code diagnostics will be disabled until the
next time the ignition power is cycled.

11

To display inactive DTCs – those that are not currently set,
but have occurred and are stored in the ECU’s memory –
apply ignition power and depress and release the brake pedal
four (4) times within 15 seconds. Following this activation,
there will be a five (5) second delay followed by a blink code
display sequence of all inactive DTCs stored.
RESET ACTIVE DTCS

Cycles of the Brake Light Power Input
Required to Enter Desired Mode
Mode

DISPLAY INACTIVE DTCS

To reset active DTCs, apply ignition power and depress and
release the brake pedal five (5) times within 15 seconds.
Following activation, there will be a five (5) second delay
followed by:
a. If no DTCs remain, a blink code message of 1-1,
(System Fully Operational - No DTCs Detected) and
the ABS indicator lamp will cease to be illuminated; or
b. If there are remaining active DTCs, a sequence of blink
codes will display all of the remaining active DTCs, and
the ABS indicator lamp will stay on.
Resetting active DTCs with blink code diagnostics does
not clear information from the DTC history. Both blink code
diagnostics and diagnostic tools can retrieve inactive DTCs,
but only diagnostic tools can clear this information.
DISPLAY ODOMETER MILEAGE
To display the trailer odometer mileage, apply ignition power
and depress and release the brake pedal seven (7) times
within 15 seconds. Following activation, there will be a five
(5) second delay followed by a blink code display of the
odometer information (x1000).
Example: 152,431 miles will be displayed as 152 (x1000) or
one (1) blink (pause); five (5) blinks (pause); two (2) blinks.
Zeros (0s) will be displayed by the Antilock Braking System
(ABS) indicator lamp strobing twice.
Odometer mileage cannot be altered with blink code
diagnostics. Complete odometer information can be retrieved
using a diagnostic tool.

17. AUXILIARY FEATURES

TIRE INFLATION SYSTEM (TIS) SENSING

REAR AXLE SUSPENSION DUMP

The iTABS module is capable of monitoring the state of
the Tire Inflation System (TIS) flow switch and it can be
configured to automatically broadcast the status of this switch
over the PLC. Contact your trailer OEM for system schematics.

Some spread-axle trailers are equipped with a rear-axle
suspension air bag dump feature to assist with cornering at
low speeds. The iTABS module may be configured to use this
feature. When this feature is used below a pre-determined
threshold vehicle speed, the ECU will partially exhaust
the rear-axle air suspension bags, and then reinflate them
when the vehicle speed rises above the threshold. For more
information about this feature, contact your local Bendix
representative.
LOW-PRESSURE WARNING EMERGENCY (LPWE)
The iTABS module can be configured for Low-Pressure
Warning Emergency (LPWE). By monitoring the status of an
external pressure switch installed in the emergency line or
delivery line of the spring brake valve, the iTABS module will
alert the driver of a low-pressure condition by illuminating the
trailer ABS warning lamp. When the vehicle is moving and
the pressure in the emergency line is below approximately
65 psi, which is the minimum pressure to release the spring
brakes, the ABS warning light will illuminate. The speed
threshold at which the alert activates is configurable. The
fault will clear once the pressure in the emergency line is
above approximately 65 psi. Contact your trailer OEM for
system schematics.
NOTE: Your trailer may be equipped with a Bendix PLC relay,
which has the ability to indicate when there is a low-pressure
condition on the emergency line, using information received
from the iTABS module. For LPWE troubleshooting, refer to
Section G in Appendix 1.

NOTE: Your trailer may be equipped with a Bendix PLC
relay, which has the ability to indicate when the TIS is active,
using information received from the iTABS module. For TIS
troubleshooting, refer to Section F in Appendix 1.
PAD WEAR-SENSING
The iTABS module is capable of monitoring the state of the
Bendix disc brake pad wear sensors installed on the air disc
brakes, and it will activate a DTC whenever it detects that
at least one (1) of the pads has reached the wear limit. The
iTABS module can broadcast this DTC over the PLC. Contact
your trailer OEM for system schematics.
NOTE: Your trailer may be equipped with a Bendix PLC
relay, which has the ability to indicate when the pad wearsensing DTC is active using information received from the
iTABS module. For PW troubleshooting, refer to Section H
in Appendix 1
.

18. DIAGNOSTIC TROUBLE CODES (DTCs)
Go to B2Bendix.com > Services & Support > Diagnostic
Trouble Code Search. Review the preliminary steps prior to
referencing the DTCs on B2Bendix.com.

IMPORTANT
FOR ALL REPAIR STEPS, FIRST COMPLETE THE
FOLLOWING:
1. Generate an ACom Diagnostic Software report.
2. Clear DTCs.
3. Continue with repair information for each
scenario.
NOTE: After completing all repair steps, drive the vehicle
to ensure the repairs were sufficient.

12

19. TROUBLESHOOTING
USING PC-BASED DIAGNOSTICS
Troubleshooting and DTC clearing, as well as beginning a
reconfiguration, may also be carried out using a PC-based
diagnostic tool such as ACom Diagnostic Software.

ADDITIONAL SUPPORT
Go to B2Bendix.com for downloads of literature and ACom
Diagnostic Software.
Refer to Appendix I in this document for the troubleshooting
flowcharts.
BENDIX TECH TEAM

ABS DIAGNOSTIC TOOLS
ACom Diagnostic Software is an RP-1210-compliant PCbased diagnostic software program that provides the highest
level of diagnostic support for the iTABS module. With ACom
Diagnostic Software, maintenance personnel can:
•

Obtain DTC information (both active and inactive)

•

Retrieve event history

•

For technical support, contact the Bendix Tech Team
by email at techteam@bendix.com or by phone at
1-800-AIR-BRAKE (1-800-247-2725), Monday through
Thursday, 8:00 a.m. to 6:00 p.m. and Friday, 8:00 a.m. to
5:00 p.m. ET. To better serve you, please record the following
information before contacting the Bendix Tech Team:
•

Bendix product model number, part number, and
configuration

Clear inactive DTCs and event history

•

Vehicle make and model

•

Verify Electronic Control Unit (ECU) configuration

•

Vehicle configuration (number of axles, tire size, etc.)

•

Perform system and component tests

•

System performance symptoms: When do they occur?

•

Read/write customer information in the scratch pad

•

•

Save and print information

What DTCs have been identified using LEDs, blink
codes, or diagnostic tools

•

Receive troubleshooting assistance

•

What troubleshooting/measurements have been
performed

•

A copy of the ACom Diagnostic Report

When diagnosing the iTABS module using a PC and ACom
Diagnostic Software, the computer’s USB port can be
connected to the vehicle’s diagnostic connector through an
RP-1210-compliant communication device.
For more information on ACom Diagnostic Software
or RP-1210-compliant tools, contact Bendix at
1-800-AIR-BRAKE (1-800-247-2725) and follow the prompts
for ACom technical support.

13

20. REPAIR
S ERVICING THE iTABS MODULE

Special considerations need to be taken to ensure the
iTABS module has been properly installed on the trailer.
These include:
•

Location and orientation of the module

•

Correct plumbing of the module

•

Correct location of the WSS

•

Configuration of the ECU for ABS system parameters

•

Installation test to verify proper installation of the ABS
system

REMOVING THE iTABS MODULE
1. Open the end cover by sliding the locking tab to the
left. If the module is to be reinstalled, retain the cover.
2. Disconnect the 7-pin ECU connector, any additional
harnesses or shorting caps used on the auxiliary
sensors, and the 4-pin WSS connectors. Ensure the old
connectors are marked appropriately for reinstallation.
3. Mark for reinstallation and then remove all air hoses
connected to the iTABS module.
4. Remove the iTABS module from the vehicle by
removing the mounting fasteners or by rotating the
entire assembly counterclockwise from the tank mount.
There is a built-in hex port that can be accessed once
the end cover has been removed.

SERVICING THE CONTROL PORT FILTER
It is the responsibility of the end-user to ensure the iTABS
module has been installed correctly and tested as per the
Bendix recommended installation guidelines and system
drawings. Incorrect installation of the iTABS module can
result in impaired ABS system functions, which could
lead to loss-of-control of the vehicle, potential collisions,
property damage, serious injuries, and/or death.
Prior to servicing the iTABS module, always perform the
following steps:
1. F
ollow all industry safe maintenance practices including
those within this document.
2. W
hen possible, before removing the module, use ACom
Diagnostic Software to save the configuration to the
desktop. After the iTABS module has been replaced, the
technician can restore the previous configuration settings.
3. Turn the power off.
4. Drain the air pressure from all reservoirs.
5. R
emove as much contamination as possible prior to
disconnecting electrical connections and air hoses.
6. N
ote the iTABS module’s mounting position on the
vehicle.

The iTABS module has an inline filter in the control port
and the supply port (see Figure 1). Inspect and clean
these filters (if any contamination is found) every four
(4) months, 34,000 miles, or 1,200 operating hours. For
severe applications, this inspection interval may be
reduced. If the filter is found to be damaged, install a
replacement. The filter should also be inspected as part
of any troubleshooting where the service brakes are slow
to apply and other possible causes have been ruled out.

INSTALLING THE iTABS MODULE

All service replacement parts for the iTABS module are
configured specifically by part number. Before removing
the module, use ACom Diagnostic Software to save
the configuration to the desktop. The technician can
use ACom Diagnostic Software to restore the previous
configuration settings.
Always ensure the correct service replacement ECU is
being installed for the original iTABS module. To verify
proper installation, perform the installation test using
ACom Diagnostic Software.
Inspect the original mounting hardware. If replacement
hardware is needed, use the appropriate grade 18 bolts, nuts,
and lock washers as per the original installation. Alternatively,
a schedule 80 (heavy-gauge steel) ¾-in. nipple for the tankmount unit can be used. Inspect the location selected for
installation and clean as necessary.

14

NOTE: Inspect all components, including the replacement
iTABS module, for any external damage, such as cracked
valve ports, electronic housings, etc. Any components
found to be damaged should not be installed on the
vehicle and must be replaced.

5°

Vertical
orientation (roll
angle) must
be within five
degrees (5°) of
vertical

5°

1. T
he iTABS module must be installed with the following
considerations (See Figures 12 through 14):
• With the exhaust port facing sideways
and unobstructed with significant free space
(> 1 in. [2.5 cm]). This orientation makes it so the
brake delivery ports always face downward.
• Within ± 100 in. (2.5 m) of the center of the axle(s)
for proper balanced brake application
Orientation

Offset
Road (Left)

Curb (Right)

0°

+

-

180°

-

+

Table 6 – Module Offset Sign
Yaw angle should be ± 10° as measured from the center line
of the trailer
• Pitch angle should be ± 10° as measured from a flat
horizontal plane

Figure 12 – Installation on Trailer (Vertical)
10°

Longitudinal
orientation
(pitch angle)
must be within
10° of vertical

10°

Driving
Direction

• Roll angle should be within ± five degrees (± 5°) as
measured from a flat horizontal plane
• Tank-mount Modules: Install the nipple fitting into
the modulator valve supply port. Rotate the entire
assembly into the tank port until secure. Overtorquing of the tank nipple could cause damage to
the valve body.

Figure 13 – Installation on Trailer (Longitudinal)
from
midpoint between
axles
±100
40"in.(1(2.5
m) m)
from
mid-point
betweenthe
the
axles

• Frame-mount Modules: Torque bolts to 221 in.-lb
(25 N•m). Torque nuts to 354 in.-lb (40 N•m).
2. R
econnect all air hoses and plugs to the module.
Depending on the installation, additional plugs may be
necessary. Thread sealant products that contain Teflon
may be used, however use of PTFE tape is not approved
and will void the ABS valve warranty as there is a potential
for tape material entering the valve and affecting the
valve’s operation. Ensure no thread sealant enters the
valve. All air hoses and fittings should be checked for
leaks prior to returning the vehicle to service.
3. R
econnect the ECU power, auxiliary (if present), and
WSS electrical connectors to the ECU. Apply a small
amount of non-conductive electrical grease to each
connector pin before reconnecting.
• Refer to the large label inside the connector cover for
wheel speed designation, “SR” or “SL.” See Figure 1.
4. L
eakage and operational tests must be performed before
returning the vehicle to service.

15

10°
10°

in. (5
(5 cm)
±2 2"
cm)
from center
from
center
of trailer
of trailer

The iTABS module must be located no more than 100 in.
(2.5 m) from the midpoint between the axles, and within