The J1939 data lines consist of an expandable data bus allowing the addition of accessory control modules. The J1939 data lines are the primary data bus. Data is prioritized and then transmitted across the J1939 data lines to the appropriate control module.

Conditions for diagnostic trouble code (DTC):
1) CAN communication does not work

Observable symptoms
1) An electronic control unit (ECU) lacking communication with other ECUs can cause a number of symptoms

Probable cause
1) Internal fault in electronic control unit (ECU)
2) Connector
3) Data link

Detailed information
1) Faults on the datalink can be localised by combining this diagnostic trouble code (DTC) with other DTCs