Fendt 05.1.95 – A039 - MFA (Multifunction Armrest): A039 - MFA, multifunction armrest: Button, auto mode stop - Faulty button, Signal fault.

The system has detected an electrical signal error, short, or stuck state specifically originating from the 'auto mode stop' button located on the tractor's 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)
• Fendt 400 Vario (COM III)
• 409
• 410
• 411
• 412
• Fendt 700 Vario (COM III)
• 711
• 712
• 714
• 716
• Fendt 800 Vario (COM III)
• 815
• 817
• 818
• Fendt 900 Vario (COM III)
• 916
• 920
• 922
• 924
• 926
• 927
• 930
• 933
• 936

1. 1

   Inspect the 'auto mode stop' button on the multifunction armrest for physical damage, sticking, or accumulated dirt/debris that might be holding the button down.

2. 2

   Connect the FENDIAS diagnostic tool (or use the tractor's onboard diagnostic terminal) to monitor the live state of the A039 MFA buttons. Check if the 'auto mode stop' button is permanently registering as 'pressed' or if the signal drops out entirely.

3. 3

   Check the main wiring harness and connectors linking the A039 MFA to the tractor's CAN bus system (e.g., using a 160-pin adapter box as noted in the workshop manual) to rule out a pinched wire in the seat suspension mechanism causing a short.

1. 1

   Power Down

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

2. 2

   Access the Armrest

   Carefully remove the plastic housing/covers on the A039 multifunction armrest to access the internal circuit boards and button matrix.

3. 3

   Clean and Inspect

   Clean the contact area behind the 'auto mode stop' button using electrical contact cleaner. Often, agricultural dust or spilled liquids cause the button to stick or short.

4. 4

   Component Replacement

   If the button switch is physically broken or the internal microswitch has failed, it must be replaced. Because Fendt typically integrates these buttons into a single printed circuit board (PCB) or keypad matrix, you may need to replace the specific MFA keypad module or the entire armrest top console if individual microswitches cannot be desoldered and replaced.

5. 5

   Reassembly and Calibration

   Reassemble the armrest, reconnect the battery, and turn the ignition on.

6. 6

   Clear Codes

   Use the FENDIAS tool or the tractor's terminal to clear the 05.1.95 fault code and test the auto mode stop function to ensure the signal fault has been resolved.