Fendt 09.1.44 – A039 - MFA / A100 - MFA: A039 - MFA, multifunction armrest. Stop button, front power lift.

This code indicates a signal fault or electrical fault with the 'Stop' button for the front power lift, located on the multifunction armrest. The system detects that the button is faulty (e.g., stuck, shorted, or sending an implausible signal). The tractor's ECU will render the front power lift stop button 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 300 Vario (COM III)
• Fendt 400 Vario (COM III)
• Fendt 700 Vario (COM III & SCR)
• Fendt 800 Vario (COM III & SCR)
• Fendt 900 Vario (COM III & SCR)
• Fendt 922
• Fendt 924
• Fendt 927
• Fendt 930
• Fendt 933
• Fendt 936

1. 1

   Inspect the front power lift stop button on the multifunction armrest for physical damage, sticking, or debris lodged around the button housing.

2. 2

   Check for signs of moisture, spilled drinks, or cleaning chemicals on the armrest.

3. 3

   Turn the tractor off completely, wait a few moments, and perform a cold start to see if the fault clears.

4. 4

   Use the FENDIAS diagnostic system or the tractor's onboard Varioterminal to monitor the live state of the A039/A100 MFA inputs and verify if the stop button is reading as constantly 'Active' (shorted/stuck) or 'Open' (disconnected).

5. 5

   Test the A039 MFA using a 160-pin adapter box to ensure the armrest is communicating properly with the A050 basic control unit via the CAN bus.

1. 1

   Disconnect Power

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

2. 2

   Disassemble the Armrest

   Carefully remove the top cover of the multifunction armrest to access the internal button clusters and printed circuit boards (PCBs).

3. 3

   Clean the Contacts

   If the button is sticking due to dirt or sticky residue, use a plastic-safe electronic contact cleaner to clean the button mechanism and the underlying microswitch on the PCB.

4. 4

   Test the Microswitch

   Use a multimeter to test the continuity of the front power lift stop button's microswitch. If the switch is internally shorted or fails to close when pressed, the switch or the cluster board must be replaced.

5. 5

   Replace the Component

   Depending on the exact armrest version, you may be able to replace the individual button membrane/switch cluster. In many cases, the entire MFA control board must be replaced if the PCB is damaged.

6. 6

   Reassemble and Calibrate

   Reassemble the armrest, reconnect the battery, and perform a cold start. Clear any stored inactive codes using the Varioterminal or FENDIAS.