Fendt 06.1.A1 – A039 (or A100) Multifunction Armrest (MFA) module: Communication fault - Button, REAR PTO

The control system has lost communication with or is receiving an invalid signal from the Rear PTO engagement button located on the multifunction armrest.

• 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 300 Vario (COM III / SCR)
• Fendt 400 Vario (COM III)
• Fendt 700 Vario (COM III / SCR)
• Fendt 800 Vario (COM III / SCR)
• Fendt 900 Vario (COM III / SCR - e.g., 922, 924, 927, 930, 933, 936)

1. 1

   Check the Rear PTO button on the armrest for physical damage, sticking, or liquid intrusion (spilled drinks are a common cause of MFA button failures).

2. 2

   Use the tractor's terminal or the FENDIAS diagnostic software to monitor the live input state of the Rear PTO button to see if the state changes when pressed.

3. 3

   Test the A039 module using a 160-pin adapter box. Check the internal ribbon cables and connectors between the armrest keypad and the MFA's internal circuit board for corrosion or loose connections.

4. 4

   Ensure there are no broader CAN bus communication errors (such as 06.1.B0) which would indicate a failure of the entire armrest communication driver rather than just the single button.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts.

2. 2

   Disassemble the Armrest

   Remove the retaining screws on the underside of the multifunction armrest to lift the top cover/keypad bezel.

3. 3

   Inspect the Keypad

   Carefully disconnect the ribbon cables connecting the keypad to the main A039 MFA board.

4. 4

   Clean / Replace

   Inspect the contacts for the Rear PTO button. If there is minor corrosion or debris, clean it with electronic contact cleaner. If the microswitch or membrane is electrically dead (open circuit), the keypad module must be replaced.

5. 5

   Reassembly

   Install the new keypad module, carefully seating the ribbon cables. Secure the armrest cover.

6. 6

   Clear Codes & Test

   Reconnect the battery, turn on the ignition, and use the terminal to clear the 06.1.A1 fault code. Start the tractor and test the Rear PTO engagement to verify the repair.