Volvo All Engines (2010 Emissions) Fault Code: SPN 2029 FMI 9 PID: PSID 201 Invalid or Missing Data from Vehicle ECU

The system uses the J1939 data links to control functions and communicates between the vehicle electronic control unit (ECU), the engine control module (ECM), the instrument cluster module and accessory systems, depending on vehicle model and option content.
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) Message missing on J1939 from the following electronic control unit (ECU): Vehicle Control Unit (VECU)

Observable symptoms
1) An electronic control unit (ECU) lacking communication with other ECUs can cause a number of symptoms
2) The engine brake does not function
3) Cruise control does not function
4) The power take-off (PTO) does not function

Probable cause
1) The electronic control unit (ECU) has a software fault or the wrong software version
2) Control unit has no supply voltage
3) Connector
4) Data link

Detailed information
1) Faults on the datalink can be localised by combining this diagnostic trouble code (DTC) with other DTCs
2) It is not probable that the data link is the problem if the diagnostic code (DTC) occurs alone as data link related DTC
3) Faulty software or software version can result in the message being absent from the datalink
4) Guided Diagnostics will automatically detect combination of data link DTCs and refer to another fault tracing procedure
5) If there are no diagnostic trouble codes (DTCs) set by the electronic control unit (ECU) from which data is missing, the cause may be power failure to that ECU