power lines, resulting in a high
voltage drop across the lines.
Measure the voltage under load by
placing a load such as a type 1157
brake light bulb between the ignition
power pin and ground pin of the
ECU connector, while the lamp is in
place.
With ignition power to the trailer,
measure the voltage between the
Ignition Power (pin 2) and Ground
(pin 3) of the ECU connector.

With
ignition
power to the
trailer, measure the
voltage between the ignition
power pin (pin 2) and the ground
pin (pin 3) of the ECU connector.
YES

Apply the service brakes. Repeat the voltage
measurement between the brake lamp power pin (pin 1)
and the ground pin (pin 3) of the ECU connector.
Are the measured ignition and brake
lamp power voltages equal to the
vehicle (supply) voltage with
1 volt tolerance?

Apply the service brakes. Repeat
the voltage measurement with
brake lamp power to the trailer,
between the brake lamp power
(pin 1) and the Ground (pin 3) of the
ECU connector.
Verify the voltage drop
measurements are no less than 1.0
VDC from the vehicle voltage at
both the ignition and brake power
inputs.

With a volt/ohm meter, check
the power and ground wiring. Look
for corroded or damaged wires or
connectors.
If repairs are made, rerun the
power-up sequence. Go to
Section A.
If proper loaded and unloaded
voltage is measured at the ECU
connector, and no corrosion or
damage is found on the wiring,
connectors, or ECU, contact the
Bendix Tech Team.

22

NO
Look for corroded or damaged wire or
connectors. Check the power supply.
If repairs are made, rerun the power-up
sequence. Go to Section A.

Measure the loaded
voltage across a type
1157 brake light bulb.
Looking into the iTABS wire harness ECU
connector measure:
Pin 2 (ignition power) to Pin 3 (ground) and
Pin 1 (brake light power) to Pin 3 (ground).

SECTION E: TROUBLESHOOTING THE WS-24 WSS

Turn off the power to the module and disconnect the WSS connector.
For additional troubleshooting steps, refer to SD-13-4860, Bendix ® WS-24™ Antilock WSS, on B2Bendix.com.

If dynamic WSS DTCs are present:

If Static WSS DTCs are present:

Rotate the affected wheel and verify a minimum of 0.25 VAC
sensor output at 0.5 RPS across the WSS pins. A properly
positioned sensor can output more than 2.0 VAC at 1 RPS.

Using a volt/ohm meter to measure the
connector pins of the sensor with a DTC,
verify 950-1950 ohms across the sensor
connector pins.

Verify/inspect the following:
•

Speed sensors properly contact the tone ring

•

The condition and retention force of the sensor sleeve

•

Proper sensor lead condition, routing and clamping sleeve

•

Condition of tone ring mounting and teeth

•

Proper number of tone ring teeth per sensed wheel

•

Proper adjustment of wheel bearings

•

Condition of foundation brakes

•

Check for corroded/damaged wiring or connectors between
the ECU and the WSS

Make repairs as needed (replace wiring and/or ABS
components).
Reset active DTCs by using any of the following methods:

Verify/inspect the following:
•

No continuity from sensor connector
pins to ground

•

Vbat not measured at either sensor
connector pins

•

Verify there is no continuity between
the sensor leads and other sensors

•

Sensor/ECU wiring and connectors
are not damaged or corroded

•

Proper sensor wire routing and
clamping

Make repairs as needed (replace wiring
and/or ABS components).

•

Blink Code Diagnostics, Section 16

Reset active DTCs by using any of the
following methods:

•

Troubleshooting, Section 19

•

Blink Code Diagnostics, Section 16

•

Troubleshooting, Section 19

(If you do not reset manually, typically these will reset automatically
after a power cycle and the vehicle has been driven for a period
of time.)
Finally, rerun the power-up sequence. Go to Section A.

Then check for Dynamic WSS DTCs
(see left column)
Finally, rerun the power-up sequence.
Go to Section A.

SL WSS and
Tristate 1
Input

SR WSS and
Tristate 1
Input

1

1

X2

X3

4

4

Looking into the iTABS Connectors
23

SECTION F: TROUBLESHOOTING THE TIS
SCENARIO 1: TIS IS ACTIVE BUT PLC MESSAGE STATUS IS INACTIVE
The following troubleshooting steps are designed to identify issues with the messaging and performance of the iTABS ECU.
Additional functionality for the PLC relay unit should also be considered and confirmed as part of these troubleshooting steps.
Tire Inflation System (TIS)
Flow Switch

iTABS X Standard Power Auxiliary
Harness K216785

Tire Inflation System Harness

BREAK LAMP VOLTAGE
IGNITION VOLTAGE
GROUND
GROUND
ABS INDICATOR LAMP (AUX 1/O 7)
AUX I/O 1

2-PIN AMP/TE CONNECTIVITY
CONNECTOR 282104

SAE J1939 (H)

™

SAE J1939 (L)

TIS Diagram

Using ACom Diagnostic Software,
look at the data monitor window
for the tire pressure supply switch
status (PID 42).

(F1)
Is the tire
pressure supply switch
status (PID 42) available on the monitor
window?

NO

Go into the ACom AUX I/O configuration.
Change the AUX I/O 1 to INPUT, select
iTIS, and select NO for inverted mode.
Click WRITE and verify the status in the
PLC message. If the status is still incorrect,
contact the Bendix Tech Team.

YES
(F2)
Is the
2-pin amp connector
of the iTABS power auxiliary
harness connected to the TIS harness
(point 2 in the TIS diagram)?

NO
Verify the connectors are fully seated.
Check for corrosion or damaged wires in
the harness.

Go to (F3) - next page

24

YES

Complete

SECTION F: TROUBLESHOOTING THE TIS (CONTINUED)
SCENARIO 1: TIS IS ACTIVE BUT PLC MESSAGE STATUS IS INACTIVE
Continued from previous page
(F3)
Using
ACom Diagnostic
Software, go to the AUX tab and check
under auxiliary function parameters. Is
the TIS INVERTED MODE
option set to
NO?

NO

Change the option to NO, write
the configuration change, and verify
if the status of the PLC message is
correct.

YES
(F4)
Measure
the continuity across the
terminals on the flow switch inside the TIS
box (point 1 in the TIS diagram).
Is there continuity?

NO

The flow switch does not
appear to be working. Contact the
TIS manufacturer for
troubleshooting steps.

YES
(F5)
Measure the
continuity across the pins
of the TIS harness (point 2 in the TIS
diagram). Is there continuity
when the TIS is
active?

NO

Troubleshoot the TIS harness
for damage.

YES
(F6)
Measure the
continuity across pins 3 and 5 of
the iTABS harness (point 3 in the
TIS diagram). Is there
continuity?

YES
Power cycle the ECU.

Go to (F7) - next page
25

NO

Troubleshoot the iTABS
harness for damage and replace if
necessary.

SECTION F: TROUBLESHOOTING THE TIS (CONTINUED)
SCENARIO 1: TIS IS ACTIVE BUT PLC MESSAGE STATUS IS INACTIVE
Continued from previous page

(F7)
Is the status on the
PLC message incorrect after
power cycle?

NO

Complete.

YES

•
•
•
•

Go into ACom Diagnostic Software AUX I/O configuration.
Set the AUX I/O 1 from INPUT to N/A and click WRITE.
Change the AUX I/O 1 back to INPUT and select iTIS in the Function Name.
Click WRITE and verify the status in the PLC message. If the status is still
incorrect, contact the Bendix Tech team.

SECTION F: TROUBLESHOOTING THE TIS
SCENARIO 2: TIS IS INACTIVE BUT PLC MESSAGE STATUS IS ACTIVE

Using ACom Diagnostic Software,
look at the data monitor window
for the tire pressure supply switch
status (PID 42).

(F8)
Is the tire
pressure supply switch
status (PID 42) available on the
monitor window?

NO

Go into the ACom AUX I/O configuration.
Change the AUX I/O 1 to INPUT, select
iTIS, and select NO for inverted mode.
Click WRITE and verify the status in the
PLC message. If the status is still incorrect,
contact the Bendix Tech Team.

YES
(F9)
Using
ACom Diagnostic
Software, go to the AUX tab and
check under auxiliary function parameters.
Is the TIS INVERTED MODE
option set to NO?
YES

26

Go to (F10) - next page

NO

Change the option to NO, write
the configuration change, and verify
if the status of the PLC message is
correct.

SECTION F: TROUBLESHOOTING THE TIS (CONTINUED)
SCENARIO 2: TIS IS INACTIVE BUT PLC MESSAGE STATUS IS ACTIVE
Continued from previous page

(F10)
Measure the
continuity across the terminals on
the flow switch inside the TIS box (point
1 in the TIS diagram). Is
there continuity?

YES

The flow switch on the
TIS is closed. Contact the TIS
manufacturer to troubleshoot the
TIS switch.

NO
Power cycle the ECU.

(F11)
Is the status on the
PLC message incorrect after
power cycle?

NO

Complete.

YES
•
•
•
•

Go into ACom Diagnostic Software AUX I/O configuration.
Set the AUX I/O 1 from INPUT to N/A and click WRITE.
Change the AUX I/O 1 back to INPUT and select iTIS in the Function Name.
Click WRITE and verify the status in the PLC message. If the status is still
incorrect, contact the Bendix Tech team.

If using a normally closed pressure switch, reverse the logic of the steps above.

27

SECTION F: TROUBLESHOOTING THE TIS (CONTINUED)
SCENARIO 3: PLC MESSAGE IS NOT BROADCASTING
Using ACom Diagnostic Software,
look at the data monitor window for
available messages.

(F12)
Do any
messages from the
trailer appear (i.e., MID 10
or MID 11)?

NO

(F13)
Is the
power light on and
is the data light blinking on the
diagnostic adapter?

NO

Verify the
ignition power
to the trailer
and diagnostic
connection.

YES

(F14)
Using ACom
Diagnostic Software, go to the
AUX tab. Is it configured as INPUT FOR
iTIS (on the AUX I/O that the
harness is connected
to)?

NO

Under TYPE, select INPUT. Under
FUNCTION, select iTIS. Click WRITE and
verify the PLC status is broadcasting.

YES
Power cycle the ECU.

(F15)
Is the status on
the PLC message incorrect after
power cycle?

NO

Complete.

YES

•
•
•
•

28

Go into ACom Diagnostic Software AUX I/O configuration.
Set the AUX I/O 1 from INPUT to N/A and click WRITE.
Change the AUX I/O 1 back to INPUT and select iTIS in the Function Name.
Click WRITE and verify the status in the PLC message. If the status is still incorrect,
contact the Bendix Tech team.

SECTION G: TROUBLESHOOTING LPWE FEATURE
SCENARIO 1: LOW PRESSURE CONDITION PRESENT (BELOW 65 PSI WITH NORMALLY
OPEN PRESSURE SWITCH), BUT PLC MESSAGE STATUS IS INACTIVE

TRISTATE
INPUT OR AUX
I/O 1

The following troubleshooting steps are designed to identify issues with the messaging and performance of the iTABS ECU.
Additional functionality for the PLC relay unit should also be considered and confirmed as part of these troubleshooting steps.

LPWE Diagram

Using ACom Diagnostic Software,
look at the data monitor window
switches tab for the parking brake
switch status (PID 70).

(G1)
Is the PID
70 park brake switch status
available on the monitor
window?

NO