Fendt 06.1.B5 – A039 - MFA (Multifunction Armrest): A039 - MFA, multifunction armrest. Button, speed selector N, REAR PTO. Communication fault.

The tractor's system has detected a communication error specifically with the Neutral (N) speed selector button for the rear Power Take-Off (PTO). The main armrest controller is not receiving the expected signal from this specific button on the keypad.

• 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)
• FENDT 400 Vario (COM III)
• FENDT 700 Vario (COM III)
• FENDT 800 Vario (COM III)
• FENDT 900 Vario (COM III)
• FENDT 916 Vario (COM III)
• FENDT 920 Vario (COM III)
• FENDT 922 Vario (COM III)
• FENDT 924 Vario (COM III)
• FENDT 926 Vario (COM III)
• FENDT 927 Vario (COM III)
• FENDT 930 Vario (COM III)
• FENDT 933 Vario (COM III)
• FENDT 936 Vario (COM III)

1. 1

   Inspect the Rear PTO Neutral button on the multifunction armrest for physical damage, sticking, or liquid intrusion

2. 2

   Check the main wiring harness connector to the A039 MFA (Connector X1401) for loose pins, corrosion, or damage

3. 3

   If the armrest is opened, check the internal ribbon cables connecting the PTO button sub-module to the main MFA circuit board

4. 4

   Use a 160-pin adapter box to test the A039 MFA as specified in the Fendt Workshop Manual (Chapter 9000 Reg. E)

5. 5

   Use the FENDIAS diagnostic tool to monitor the button state and check for broader CAN bus communication errors. If multiple buttons are failing (e.g., codes 06.1.B6 for 540 speed, 06.1.B7 for 750 speed), the entire keypad module or bus connection is likely at fault.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts while working on the CAN bus components.

2. 2

   Access the MFA

   Remove the retaining screws on the A039 multifunction armrest housing to access the internal electronics.

3. 3

   Inspect/Clean

   Carefully disconnect the ribbon cable for the rear PTO speed selector keypad. Clean the contacts with electronic contact cleaner and reseat the connection.

4. 4

   Replace Component

   If the connection is secure but the fault persists, the button module has failed internally. Depending on the specific armrest revision, you will need to replace either the specific PTO keypad sub-module or the entire A039 Multifunction Armrest assembly.

5. 5

   Reassembly

   Reconnect all internal cables, secure the armrest housing, and reconnect the battery.

6. 6

   EOL Programming

   If a new A039 MFA assembly is installed, you must perform EOL (End of Line) programming using the FENDIAS diagnostic tool so the tractor's basic control unit (A050) recognizes the new hardware on the bus.