Volvo All Engines (2004 Emissions) Fault Code: SID 231 FMI 2 CAN1 J1939 Communication Link A

Fault Condition: Code SID 231 will set when the Vehicle Electronic Control Unit (VECU) is unable to send and/or receive information across the J1939 data line. If either the Vehicle Electronic Control Unit (VECU) or the Engine
Management System (EMS) Module loses communication on the J1939 data line, code SID 231 will set and the Electronic Malfunction Lamp (EML) will turn on. The fault will become inactive if communication resumes. If communication is lost on both the J1587 and J1939 data lines the engine will NOT run.

Possible repairs:

Turn the ignition key OFF first.

1) Disconnect the Vehicle Electronic Control Unit (VECU) connectors A, B and C. Check for continuity between Vehicle Electronic Control Unit (VECU) connector C pin 4 and all other pins (except Vehicle Electronic Control Unit (VECU) connector C pin 5) on connectors A, B and C. Then check for continuity between Vehicle Electronic Control Unit (VECU) connector C pin 5 and all other pins (except Vehicle Electronic Control Unit (VECU) connector C pin 4) on connectors A, B and C. If continuity exists, repair or replace the damaged data line harness or connectors. If continuity does not exist, replace the Vehicle Electronic Control Unit (VECU).
2) Disconnect the Vehicle Electronic Control Unit (VECU) connector C. Check for continuity between Vehicle Electronic Control Unit (VECU) connector C pin 5 and pin D of the Data Link Connector (DLC). Then check for continuity between Vehicle Electronic Control Unit (VECU) connector C pin 4 and pin C of the Data Link Connector (DLC). If the continuity exists, replace the Vehicle Electronic Control Unit (VECU). If the continuity does not exists, locate and repair the open in the data line and retest the system.
3) Disconnect the CAN-BUS Termination Resistor connector. Check for continuity between pins 1 and 2 of the CAN-BUS Termination Resistor. If the resistance is NOT between 115–125 Ohms, replace the CAN-BUS Termination
Resistor.
4) Disconnect the Vehicle Electronic Control Unit (VECU) connector C. Check the resistance between the Vehicle Electronic Control Unit (VECU) connector C pins 4 and 5 on the VECU side. If continuity is between 115–125 Ohms, locate and repair an open in the data line. If continuity is NOT between 115–125 Ohms, check the Vehicle Electronic Control Unit (VECU) harness and all connections for loose, corroded or damaged terminals and repair or replace as necessary. If no loose, corroded or damaged terminals are found, replace the Vehicle Electronic Control Unit (VECU).