2
Diagnostics, Troubleshooting and Testing
27
WABCO
Maintenance Manual MM-1306 (Revised 08-18)
Table D: Display Harness Connector Pins
Radar and Display Circuit Testing
The following radar and display harness check should be performed
when various DTCs occur. Refer to the Troubleshooting Guide and
the Diagnostic Trouble Code Table for further information.
Power and Ground Checks
앫
Verify vehicle batteries, charging system and fuses are in good
working condition.
앫
Load test battery and ignition circuits to ground at the ECU
harness using a 2-4 amp sealed lamp and verify lamp does not
flicker and it is on steady.
앫
Take measurements at the radar and display harness pins.
Measurements should read as follows:
J1939 Serial Communications Testing
Electrical Checks
앫
Verify J1939 High and Low have correct voltage readings, Key
ON, while datalink communications are active.
앫
For resistance measurements, the vehicle battery must be
disconnected and the ignition must be OFF.
Measurements should read as follows:
Component Message Fault
Troubleshooting
Refer to the Diagnostic Trouble Code Table for further information.
The following are the troubleshooting sections and sub-sections
referenced in the last column of the Diagnostic Trouble Code Table.
Message Timeout
Occasionally the CMS will generate Message Timeout DTCs due to
data not being received from the ECUs connected on the SAE J1939
network. This can occur if the cruise control, engine, transmission,
ABS, engine retarder or driveline retarder ECUs have been
re-flashed with new software that is incorrect, was not downloaded
correctly or has the incorrect parameter set. This information may
reside in the vehicle OEM ECU database. It is also possible that
various ECUs are not operating correctly on the SAE J1939 network
or DTCs have occurred during diagnostic procedures. Perform the
following procedure if a Message Timeout DTC is present:
NOTE:
Certain diagnostic software programs, other than
TOOLBOX™ Software, can generate Timeout DTCs. Verify code is
Active on the display without any diagnostic software connected to
the vehicle.
1.
Determine if the software or parameter set from the
appropriate ECU has recently been modified. Install the correct
software and parameter set if required.
2.
Verify that the SAE J1939 network is functioning correctly. Use
the Radar Harness Electrical Checks procedure to repair any
SAE J1939 network issues.
3.
After any ECU servicing has been completed, cycle the ignition
OFF for one minute and then back ON for one minute with the
engine idling to clear the system DTC. Verify that the DTC has
been cleared.
Pin
Circuit
1
No Connection
2
No Connection
3
No Connection
4
Ignition
5
Ground
6
J1939 Low
7
J1939 High
8
No Connection
Location
Measurement
Supply Voltage, Battery to
chassis Ground
9.0-16.0V for 12V system
Supply Voltage, Ignition to
chassis Ground
9.0-16.0V for 12V system
Ground pin to chassis ground
Less than 1 ohm resistance
Location
Measurement
Across J1939 High and Low
Approximately 60 ohms
J1939 Low voltage
0.1V-2.4V
J1939 High voltage
2.5V-5.0V
J1939 High or J1939 Low to
Ground or Power Supply
No continuity
