4

Trailer Axle #4, Left Wheel, Wear Sensor Shorted to Ground or Open Circuit

B

22761

3

Trailer Axle #4, Right Wheel, Wear Sensor Shorted to Voltage

A

22761

4

Trailer Axle #4, Right Wheel, Wear Sensor Shorted to Ground or Open Circuit

B

DTC NAME

Wear Sensor

DTC DESCRIPTION

Table 5 – Diagnostic Trouble Codes (DTCs)

8

GO TO
SERVICE
ACTION
CODE
LISTED IN
TABLE 6

NOTE: Unless otherwise specified, diagnostics should be
done with the vehicle ignition on and with the engine not
running.

Trailer Axle #1 Right,
Curbside Brake

Trailer Axle #2 Right,
Curbside Brake

Trailer Axle #3 Right,
Curbside Brake

Trailer Axle #4 Right,
Curbside Brake

Trailer Axle #1 Left,
Roadside Brake

Trailer Axle #2 Left,
Roadside Brake

Trailer Axle #3 Left,
Roadside Brake

Trailer Axle #4 Left,
Roadside Brake

FRONT

iSense™ Pro ECU

Continuous Sensor
Harness Connector

PIN

DESCRIPTION

COLOR*

A

Signal

Black

B

Sensor Power

Yellow

C

Sensor Ground

Brown

*Color applies to sensor harnesses supplied by
Bendix or Knorr-Bremse

Torque Spec: 1.0 - 1.1 N•m

Figure 6 – Bendix® iSense™ Pro Trailer Wear-Sensing Electronic Control Unit (ECU) Layout

9

SERVICE ACTION CODE TABLE
Refer to Table 6. To clear active Diagnostic Trouble Codes (DTCs) (as situations are remedied), simply clear (or “self‑heal”)
by removing and re‑applying ignition power. Alternately, DTCs may be cleared by using a PC‑based diagnostic tool.

Service
Action
Code

Troubleshooting Measure
1. Locate the Faulted Wheel-end Brake.
Disconnect the Continuous Sensor
Harness Connector, and with a Digital
Multi-Meter (DMM), measure the DC
voltage between Pin A and Pin B
within the Continuous Sensor Harness
Connector.

Measured Voltage
• 0-4.5V – Signal line not shorted to power source.
Proceed to Step 5.
• 4.5-5.5V – Signal line shorted to sensor power.
Proceed to Step 2.
• > 5.5V – Signal line shorted to vehicle power.
Proceed to Step 5.

2. Locate the Faulted Wheel-end Brake.
Using a DMM in Continuity Check
Mode, check the continuity between
Pin A and Pin B within the Continuous
Sensor Harness Connector.

Continuity Measurement Results
• Continuity is Present: Short between sensor line and
sensor power confirmed.
o If secondary connectors are present between the
Electronic Control Unit (ECU) Connector and the
Continuous Sensor Harness Connector, proceed to
Step 3.
o If secondary connectors are not present between the
ECU Connector and the Continuous Sensor Harness
Connector, proceed to Step 4.
• Continuity is Not Present: Short not present between
sensor line and sensor power.
o Possible intermittent short. Check the entire run of
the harness between the ECU Connector and the
Continuous Sensor Harness Connector connected
to the Faulted Wheel-end Brake. If damaged wire
insulation is not found, proceed with replacing the
ECU with a known good ECU. If the problem persists,
further diagnostics are needed to locate the short. If
the problem ceases, then proceed with replacing the
ECU through warranty or aftermarket.

3. Locate the Faulted Wheel-end Brake
and follow the Continuous Sensor
Harness Connector to any OE-specific
connectors between the brake and
the ECU Connector. Using a DMM
in Continuity Check Mode, check the
continuity between the Sensor Power
and Sensor Signal Pins at each OEspecific connector.

Continuity Measurement Results
• Continuity is Present: Short circuit confirmed in supply line.
Supply line must be replaced.
• Continuity is Not Present: Short not present in supply line.
Proceed to Step 4.

A

Table 6 – Service Action Codes

10

Action

Service
Action
Code

A

Troubleshooting Measure

Action

4. Locate the Bendix® iSense™ Pro
Electronic Control Unit (ECU) and
disconnect the ECU Connector.
Using a Digital Multi-Meter (DMM) in
Continuity Check Mode and referring
to Figure 3 and Table 2, check the
continuity between the Sensor Power
Out Pin corresponding to the axle
on which the Faulted Wheel End
resides and the Sensor Signal Pin
corresponding to the Faulted Wheel
End within the ECU Connector.

Continuity Measurement Results
• Continuity is Present: Short circuit confirmed in vehicle
harness. Short must be found and repaired.
• Continuity is Not Present: Short not present between
sensor line and sensor power.
o Possible intermittent short. Check the entire run of
the harness between the ECU Connector and the
Continuous Sensor Harness Connector connected
to the Faulted Wheel-end Brake. If damaged wire
insulation is not found, proceed with replacing the
ECU with a known good ECU. If the problem persists,
further diagnostics are needed to locate the short. If
the problem ceases, then proceed with replacing the
ECU through warranty or aftermarket.

5. Locate the iSense Pro ECU and
disconnect the ECU Connector. Using
a DMM in Continuity Check Mode,
check the continuity between Pin 1 and
the Sensor Signal Pin corresponding to
the Faulted Wheel End within the ECU
Connector.

Continuity Measurement Results
• Continuity is Present: Short circuit confirmed in vehicle
harness. Short must be found and repaired.
• Continuity is Not Present: Short not present between
sensor line and sensor power.
o Possible intermittent short. Check the entire run of
the harness between the ECU Connector and the
Continuous Sensor Harness Connector connected
to the Faulted Wheel-end Brake. If damaged wire
insulation is not found, proceed with replacing the
ECU with a known good ECU. If the problem persists,
further diagnostics are needed to locate the short. If
the problem ceases, then proceed with replacing the
ECU through warranty or aftermarket.

6. Locate the Faulted Wheel-end Brake.
Using a DMM in Continuity Check
Mode, check the continuity between
Pin C within the Continuous Sensor
Harness Connector and a chassis
ground.

Continuity Measurement Results
• Continuity is Present: Ground circuit working properly.
Check the entire run of the harness between the ECU
Connector and the Continuous Sensor Harness Connector
connected to the Faulted Wheel-end Brake. If damaged
wire insulation is not found, proceed with replacing the ECU
with a known good ECU. If the problem persists, further
diagnostics are needed to locate the short. If the problem
ceases, then proceed with replacing the ECU through
warranty or aftermarket.
• Continuity is Not Present: Sensor ground circuit is open.
Open circuit must be found and repaired.

Table 6 – Service Action Codes

11

Service
Action
Code

B

Troubleshooting Measure
1. Locate the Faulted Wheel-end Brake.
Disconnect the Continuous Sensor
Harness Connector and with a Digital
Multi-Meter (DMM) in Continuity Check
Mode, check the continuity between
Pin B and Pin C within the Continuous
Sensor Harness Connector.

Continuity Measurement Results
• Continuity is Present: Short between sensor line and
sensor ground confirmed.
o If secondary connectors are present between the
Electronic Control Unit (ECU) Connector and the
Continuous Sensor Harness Connector, proceed to
Step 2.
o If secondary connectors are not present between the
ECU Connector and the Continuous Sensor Harness
Connector, proceed to Step 3.
• Continuity is Not Present: Short not present between
sensor line and sensor ground.
• Possible intermittent short. Check the entire run of the
harness between the ECU Connector and the Continuous
Sensor Harness Connector connected to the Faulted
Wheel-end Brake. If damaged wire insulation is not found,
proceed with replacing the ECU with a known good ECU.
If the problem persists, further diagnostics are needed to
locate the short. If the problem ceases, then proceed with
replacing the ECU through warranty or aftermarket.

2. Locate the Faulted Wheel-end Brake
and follow the Continuous Sensor
Harness Connector to any OE-specific
connectors between the brake and the
ECU Connector. At each OE-specific
connector with the DMM in Continuity
Check Mode, check the continuity
between the Sensor Power and Sensor
Signal Pins.

Continuity Measurement Results
• Continuity is Present: Short circuit confirmed in supply line.
Supply line must be replaced.
• Continuity is Not Present: Short not present in supply line.
Proceed to Step 3.

3. Locate the Bendix® iSense™ Pro ECU
and disconnect the ECU Connector.
Using a DMM in Continuity Check
Mode and referring to Figure 3 and
Table 2, check the continuity between ​
the Sensor Ground Pin corresponding
to the axle on which the Faulted Wheel
End resides​and ​the Sensor Signal Pin
corresponding to the Faulted Wheel
End​within the ECU Connector.

Continuity Measurement Results
• Continuity is Present: Short circuit confirmed in vehicle
harness. Short must be found and repaired.
• Continuity is Not Present: Short not present between
sensor line and sensor power. Proceed to Step 4.

Table 6 – Service Action Codes

12

Action

Service
Action
Code

Troubleshooting Measure

Action

4. Locate the Faulted Wheel-end Brake
Continuity Measurement Results
and disconnect the Continuous Sensor • Continuity is Present: Open circuit not present in sensor
Harness Connector. Locate the
signal line. Proceed to Step 5.
Bendix® iSense™ Pro Electronic Control • Continuity is Not Present: Open circuit present in sensor
Unit (ECU) and disconnect the ECU
signal line.
Connector. Using a Digital Multi-Meter
o Check the entire run of the harness between the
(DMM) in Continuity Check Mode and
ECU Connector and the Continuous Sensor Harness
referring to Figure 3 and Table 2, check
Connector connected to the Faulted Wheel-end Brake.
the continuity between the Sensor
If damaged wiring is not found, proceed with replacing
Signal Pin corresponding to the Faulted
the ECU with a known good ECU. If the problem
Wheel End within the ECU Connector
persists, further diagnostics is needed to locate
and Pin A within the Continuous Sensor
the short. If the problem ceases, then proceed with
Harness Connector.
replacing the ECU through warranty or aftermarket.

B

5. Locate the Faulted Wheel-end Brake
and disconnect the Continuous
Sensor Harness Connector. Locate
the Sense Pro ECU and disconnect
the ECU Connector. Using a DMM in
Continuity Check Mode and referring
to Figure 3 and Table 2, check the
continuity between the Sensor Ground
Pin corresponding to the axle on
which the Faulted Wheel End resides
within the ECU Connector and Pin B
within the Continuous Sensor Harness
Connector.

Continuity Measurement Results
• Continuity is Present: Open circuit not present in sensor
power line. Proceed to Step 6.
• Continuity is Not Present: Open circuit present in sensor
power line.
o Check the entire run of the harness between the
ECU Connector and the Continuous Sensor Harness
Connector connected to the Faulted Wheel-end Brake.
If damaged wiring is not found, proceed with replacing
the ECU with a known good ECU. If the problem
persists, further diagnostics is needed to locate
the short. If the problem ceases, then proceed with
replacing the ECU through warranty or aftermarket.

6. Locate the iSense Pro ECU and
disconnect the ECU Connector. Using
a DMM in Continuity Check Mode
and referring to Figure 3 and Table
2, check the continuity between ​the
Sensor Ground Pin corresponding to
the axle on which the Faulted Wheel
End resides​and ​the Sensor Signal Pin
corresponding to the Faulted Wheel
End​within the ECU Connector.

Continuity Measurement Results
• Continuity is Present: Short circuit in vehicle harness
confirmed. Short must be found and repaired.
• Continuity is Not Present: Short not present between
sensor ground and sensor signal.
o Possible intermittent short. Check the entire run of
the harness between the ECU Connector and the
Continuous Sensor Harness Connector connected
to the Faulted Wheel-end Brake. Additionally, check
the entire run of the harness between the ECU
Connector and where it is connected on the vehicle
harness. If damaged wire insulation is not found,
proceed with replacing the ECU with a known good
ECU. If the problem persists, further diagnostics are
needed to locate the short. If the problem ceases, then
proceed with replacing the ECU through warranty or
aftermarket.

Table 6 – Service Action Codes

13

TROUBLESHOOTING: ELECTRONIC
CONTROL UNIT (ECU) WIRING HARNESS
CONNECTORS
Bendix Air Disc Brake (ADB) Wear-sensing Electronic
Control Units (ECUs) are designed to interface with a
Deutsch DTV connector as referenced in Table 7. Follow
the connector manufacturer’s specifications for creating or
repairing wiring harnesses
®

IMPORTANT
All wiring harness connectors must be properly seated.
The use of secondary locks is strongly advised.

All unused ECU pins must be covered and receive
proper environmental protection.
As a matter of good practice and to ensure maximum
system robustness, always use the maximum size wire
supported by the wire harness connectors for ignition and
ground. All sensor and serial communications circuits
(J1939) must use twisted pair wiring (one to two twists
per inch). Reference the appropriate SAE document for
additional details.

All wires must be carefully routed to avoid contact with
rotating elements. Wiring must be properly secured
approximately every 6 to 12 inches using UV-stabilized,
non‑metallic hose clamps or bow‑tie cable ties to
prevent pinching, binding, or fraying.
It is recommended that wires be routed straight out of a
connector for a minimum of three (3) inches before the
wire is allowed to bend. Ignition power and ground wires
should be kept to a minimum length. If convoluted tubing
is used, its inner diameter must match the size of the wire
bundle as closely as possible.
WIRE
REQUIREMENT

Wiring harness lengths must be carefully selected
for the vehicle. Harnesses that are too long increase
the possibility of electrical interference and wiring
damage. Excess lengths of wire are not to be wound
to form coils; instead, re-route, repair, or replace the
wiring harness. Do not attempt to stretch harnesses
that are too short, as mechanical strain can result in
wire breakage.
Route sensor wiring coming out of the wheel-ends away
from moving brake components. Sensor wiring needs to
be secured to the axle to prevent excess cable length and
wiring damage.
Following the axle, the sensor wires must be attached along
the length of the service brake hoses using cable ties with
ultraviolet protection and secured every 6 to 8 inches (152
to 203 mm). Sufficient – but not excessive – cable length
must be provided to permit full suspension travel and
steering axle movement. Install wires so that they cannot
touch rotating elements such as wheels, brake discs, or
drive shafts.
Bendix does not recommend using standard tie‑wraps to
secure wiring harnesses directly to rubber air lines. This
may cause premature wiring failure from the pressure
exerted on the wiring when air pressure is applied through
the air line. Non‑metallic hose clamps or bow‑tie tie‑wraps