Troubleshooting guide

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Trailer ABS Operation Continued
•
Axle Control Mode uses a single ABS modulator
to control both sides of a given axle or axles
• Side control uses ABS modulators to control each
side of a vehicle separately. The modulator may
control one or more wheels
• Fail Safe Mode reverts the system to non-ABS
braking in the event of a system malfunction
Note: The ABS indicator lamp (mandated by govern-
ment regulations) is illuminated whenever there is an
active diagnostic trouble code. This lamp will remain
illuminated (whenever the power is on) until the
condition is cleared. The lamp may also be used to
display diagnostic blink codes when troubleshooting.
Trailer ABS Features
The latest releases of trailer ABS feature:
• Auxiliary Design Language (ADL) which allows
customized trailer features to communicate via the
ABS ECU with the tractor. Potential examples
are: weight, lift axle position, tire temperature and
inflation status, slider pin position, refrigeration
temperature, load presence, and proximity/
reverse alarm.
• Auto-configuration at power-up.
• Customer-defined data storage
• Odometer functionality, including total, trip and
service interval tracking
Troubleshooting Truck, Tractor
and Trailer ABS
Bendix ECU controllers contain self-testing diagnostic
circuitry that continuously checks for the normal
operation of internal components and circuitry, as well
as external ABS components and wiring. See the Service
Data Sheet for the ABS controller for full
troubleshooting information.
Diagnostic Trouble Codes: General
When an erroneous system condition is detected, the
ECU controllers:
1. Illuminates the appropriate indicator lamp(s) and
disengages part or all of the ABS and ATC functions.
2. Places the appropriate trouble code information in
the ECU memory.
3. Communicates the appropriate trouble code
information over the serial communications
diagnostic link as required.
Depending on the ECU, the diagnostic trouble codes
may be retrieved using “blink codes” (using the dash
or trailer ABS indicator lamp), by attaching to the
vehicle diagnostic connector (see above) a hand-held
diagnostic tool such as the Bendix Remote Diagnostic
Unit (RDU
™
), or a PC-based diagnostic tool such as
the Bendix
®
ACom
™
Diagnostics program, or by reading
the LEDs on the front of the ECU (such as on the
EC-30
™
controller).
Located on
Dash Panel
Located Under
Dash Panel
Or
Typical Vehicle Diagnostic Connector Locations
POWER LINE WITHOUT PLC SIGNAL
POWER LINE WITH PLC SIGNAL
Controllers with PLC
Since March 1, 2001, all towing vehicles must have an
in-cab trailer ABS Indicator Lamp. Trailers transmit
the status of the trailer ABS over the power line to
the tractor using a Power Line Carrier (PLC) signal
(see right panel). Typically the signal is broadcast by
the trailer ABS ECU. The application of PLC technology
for the heavy vehicle industry is known as
“PLC4Trucks.”
Trailer ABS Operation and Features, PLC, Troubleshooting