Fendt 06.1.81 – A039 - MFA (Multifunction Armrest) / A100 - MFA: A039 - MFA, multifunction armrest. Button, REAR PTO. Counter error.

The control unit has detected an abnormal signal count, debounce error, or internal electrical fault originating from the Rear PTO ON/OFF button located on the multifunction armrest. The expected digital signal pulses from the button press do not match the programmed parameters, often due to a sticking switch or internal circuit failure.

• 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 500 Vario (SCR)
• Fendt 700 Vario (COM III / SCR)
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III / S4)

1. 1

   Inspect the Rear PTO ON/OFF button on the armrest for physical damage, sticky residue, or debris that might cause it to mechanically bind.

2. 2

   Connect the FENDIAS diagnostic tool and monitor the live state of the MFA module to observe if the Rear PTO button state changes properly when pressed.

3. 3

   Check the main wiring harness and adapter box connections (e.g., X1401 connector) leading to the MFA module for loose pins, moisture, or corrosion.

4. 4

   Look for accompanying CAN bus communication faults (such as 06.1.A1 or 06.1.B0) which would indicate a broader communication failure rather than an isolated button issue.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical spikes during component handling.

2. 2

   Clean the Switch

   If the button is mechanically sticking, attempt to clean the edges of the Rear PTO button with a plastic-safe electrical contact cleaner.

3. 3

   Component Replacement

   If the button is internally shorted or the counter error persists after cleaning, the faulty switch must be replaced. Depending on the specific armrest generation, the individual button membrane/switch may not be serviced separately, requiring the replacement of the MFA keypad or the upper armrest console assembly.

4. 4

   Reassembly & Power Up

   Reconnect the MFA harness and restore battery power.

5. 5

   EOL Programming

   Use the FENDIAS service program to clear the stored 06.1.81 fault code. If a new MFA module or keypad was installed, you must perform EOL (End of Line) programming and calibration so the A050 basic control unit recognizes the new armrest module.

6. 6

   Verification

   Start the tractor and test the Rear PTO engagement from the armrest to confirm the repair.