Fendt 1.2.B4 – A051 - ECU, Engine Control Unit (EDC 7): A051 - ECU, engine control unit (EDC 7) - CAN-message missing

Communication failure on the CAN bus network. The CAN bus connection between the enhanced control module (A002) or the pump control unit (A020/A021) and the engine control unit (A051) has been interrupted or is faulty. When active, the tractor experiences a loss of enhanced features (TMS may switch off), torque is limited, and the operator may only have access to the manual foot throttle, or the engine may only run at idle.

• 411 Vario COM III
• 412 Vario COM III
• 413 Vario COM III
• 414 Vario COM III
• 415 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
• 718 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• 309
• 310
• 311
• 312
• 409
• 410
• 411
• 412
• 711
• 712
• 714
• 716
• 815
• 817
• 818
• 916
• 920
• 924
• 926
• 930
• 936

1. 1

   Connect the FENDIAS or SERDIA service diagnostics program to the tractor, read the fault memory to confirm 1.2.B4 (often associated with FC:0070), and check for any secondary voltage or sensor faults.

2. 2

   Consult the tractor's circuit diagram (Sheet 36 or Sheet 22/6) and inspect the CAN bus wiring harness between the A051 (Engine ECU) and the A002 (Enhanced Control ECU) for chafing, breaks, or short circuits.

3. 3

   Disconnect the harnesses at the EDC 7 and check for pushed-back pins, corrosion, or moisture ingress.

4. 4

   Verify that the engine control unit has the correct EOL (End of Line) programming, as a corrupted data record or mismatched engine configuration can trigger CAN communication dropouts.

1. 1

   Isolate the Battery

   Turn off the ignition and disconnect the battery via the battery disconnect relay to prevent electrical spikes during repair.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a broken wire or corroded connector on the CAN bus line between A051 and A002, splice/repair the wiring using OEM-approved weather-sealed connectors, or replace the damaged harness section.

3. 3

   Reprogram the ECU

   If the wiring is perfectly intact, the fault may stem from a software corruption. Use the SERDIA tool to flash/reprogram the EOL new data record to the A051 control unit.

4. 4

   Replace the ECU

   If the EDC 7 module has suffered internal hardware failure, remove the module from its mounting bracket and install the replacement unit.

5. 5

   Clear Faults

   Reconnect the battery. Connect the SERDIA diagnostic tool and delete the error code (FC:0070) from the fault memory.

6. 6

   Test Drive

   Start the engine and verify that the tractor responds to all throttle inputs and that enhanced features (like TMS) are fully operational without defaulting to idle mode.