Fault Code Guide

Miscellaneous Faults Troubleshooting (SID 254)
MID SID FMI Problem Test Test Result Action
136 254 14 ECU Mounting Check ECU mounting. Replace
the ECU if fault persists.
Extreme banked
road (measured
acceleration not
plausible)
No correction required. This fault
is for reporting only.
Accelerometer
linearity
(measured
acceleration not
plausible)
Table 17, Miscellaneous Faults Troubleshooting (SID 254)
PLC Troubleshooting
Special tools to test PLC are currently in develop-
ment and will be available soon. It is anticipated that
these tools will have the capability to do the follow-
ing:
• Simulate a trailer ABS PLC message to the
tractor ABS ECU to turn on the trailer ABS
warning lamp. This tests the functionality of the
vehicle portion of the system.
• Detect a PLC message from the trailer ABS.
This tests the functionality of the trailer portion
of the system.
At present, the only way to test the trailer ABS warn-
ing lamp system with PLC is to connect the vehicle
to a trailer with PLC. When the ignition is turned on,
the trailer ABS lamp should come on for a few sec-
onds, then go out. This indicates that there is PLC
communications, the warning lamp works, and there
are no faults in the trailer ABS. If the trailer ABS
lamp remains on, there is a fault in the trailer ABS.
Refer to the trailer ABS manufacturer’s literature for
troubleshooting the trailer ABS system.
NOTE: It is also possible that the trailer ABS
lamp circuit is shorted to ground, causing the
lamp to stay on.
PLC Filter Testing
Testing of the PLC filter is possible. Before perform-
ing these tests make sure the ignition is OFF. Dis-
connect the 2-wire connector (green/yellow wires)
and the 2-wire connector (blue wires) from the filter.
The PLC filter is located near the trailer receptacle
on the frame rail or crossmember. Follow the single
blue wire from the PLC filter to the primary or supple-
mental receptacle. Whichever trailer receptacle the
blue wire is connected to carries the PLC signal.
NOTE: For the following steps, you will need a
digital multimeter (DMM) with capacitance mea-
suring capability.
1. At the 2-pin connector with the green and yellow
wires, use a DMM to measure the resistance
across the green and yellow wires.
• If the reading is less than 0.5 ohms, go to
the next step.
• If the reading is more than 0.5 ohms, the
tractor ABS power circuit is open in the
PLC filter. Replace the filter.
2. Determine the receptacle (primary or supplemen-
tal) that supplies power to the trailer ABS. Using
a DMM, connect one lead to pin 7 of the recep-
tacle that supplies power to the trailer ABS and
the other lead to the 2-pin connector on the PLC
filter that has the two blue wires. Measure the
resistance at both pins on the 2-pin connector.
• If the reading is less than 1.0 ohm, go to
the next step.
• If the reading is more than 1.0 ohm, there
is an open circuit either between the 7-way
trailer receptacle and the PLC filter, or in
the PLC filter itself. Repair the harness or
replace the PLC filter as necessary.
Meritor WABCO Pneumatic Antilock Braking System
(ABS)
42.00
ABS System Troubleshooting
Business Class M2 Workshop Manual, Supplement 2, June 2002 300/17