Fendt 04.1.B3 – A002 / A050: Fault in EPROM programming (rapid reversing ramp parameters)

The memory chip (EPROM) inside the control unit has lost or corrupted the specific calibration data that dictates how aggressively the tractor behaves during rapid directional changes (shuttle shifting).

• 309 Vario COM III
• 310 Vario COM III
• 311 Vario COM III
• 312 Vario COM III
• Fendt 300 Vario (including COM III)
• Fendt 400 Vario / Farmer 400
• Fendt 700 Vario / Favorit 700
• Fendt 800 Vario
• Fendt 900 Vario / Favorit 900 (including COM III)

1. 1

   Verify tractor operation: Confirm that the tractor can still drive and perform rapid reversing. The system should default to standard values. If the tractor cannot drive, there may be a broader CAN bus or power supply issue.

2. 2

   Check power supply: Voltage drops or spikes can cause EPROM memory corruption. Check the power supply to the CAN bus and the ECU on fuse board A013 (specifically fuses F040 and F041).

3. 3

   Attempt to clear the code: Use the tractor's onboard diagnostic terminal to clear the fault memory. Restart the tractor to see if the code returns immediately. If it does, the EPROM data is permanently corrupted and requires reprogramming.

1. 1

   Connect diagnostic interface

   Connect the AGCO 2x4 CANUSB diagnostic interface and launch the FENDIAS diagnostic software.

2. 2

   Establish ECU communication

   Establish communication with the A002 (Enhanced Control) or A050 (Basic Control Unit) ECU.

3. 3

   Perform EOL programming

   Perform an EOL (End-Of-Line) programming routine to re-flash the EPROM with the correct rapid reversing ramp parameters for that specific chassis.

4. 4

   Clear fault codes

   Clear the fault codes from the ECU memory.

5. 5

   Test drive

   Test drive the tractor and perform a rapid reverse maneuver to ensure the custom parameters are retained and the code does not return.

6. 6

   Repair or replace ECU

   If the EOL programming fails or the ECU refuses to hold the memory, the internal EPROM chip is physically damaged. The ECU must be removed and either sent to an agricultural electronics repair specialist or replaced entirely.