Fendt 0A.1.D1 – A039 - MFA / A100 - MFA: A039 (or A100) - MFA, multifunction armrest. Button, hydraulic circuit 4.

The system has detected a 'Signal fault' or a 'Faulty button' specifically related to the hydraulic circuit 4 control button located on the Vario joystick. The system locks out the affected valve for safety, making the button and associated hydraulic circuit completely inoperable until the next trouble-free cold start.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt 200 Vario (V/F/P)
• Fendt 300 Vario (COM III / S4)
• Fendt 400 Vario (COM III)
• Fendt 500 Vario (S4)
• Fendt 700 Vario (COM III / SCR / Gen6)
• Fendt 800 Vario (COM III / SCR)
• Fendt 900 Vario (COM III / SCR)

1. 1

   Check the hydraulic circuit 4 button on the joystick for physical damage, sticking, or debris lodged in the housing.

2. 2

   Perform a cold start reset by turning the tractor off completely, waiting for systems to power down, and restarting to see if the code clears.

3. 3

   Use the FENDIAS service diagnostics program or the onboard terminal to read switch states in the MFA diagnostic menu, verifying if the ECU receives a constant 'pressed' signal or no signal.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts while working on the armrest.

2. 2

   Clean the Switch

   If the button is physically sticking, use a plastic-safe electrical contact cleaner around the edges of the button to dislodge dirt or sticky residue.

3. 3

   Cap Replacement

   If the physical plastic button cap is broken but the internal switch still clicks, carefully pry off the broken cap and snap a replacement cap into place.

4. 4

   Joystick Disassembly & Repair

   If the internal microswitch has failed (no click, or constant short), the joystick handle must be disassembled. Send the joystick to a specialized agricultural electronics repair service for board-level microswitch replacement, or replace the entire joystick assembly.

5. 5

   Reassembly and Calibration

   Reinstall the joystick/armrest components and reconnect the battery.

6. 6

   Clear Codes

   Perform a cold start. Confirm that the 0A.1.D1 fault code has moved from 'Active' to 'Stored' and clear the fault log. Test hydraulic circuit 4 for proper operation.