Fendt 08.1.48 – A039 Multifunction Armrest (MFA): A039 - MFA, multifunction armrest. Button, rear power lift.

Communication fault between the rear power lift button on the multifunction armrest and the tractor's control system.

• 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)
• Fendt 900 Vario (COM III / SCR)

1. 1

   Perform a cold start reset by turning the ignition OFF, waiting for the system to power down completely, and turning it back ON.

2. 2

   Test the rear power lift using the external buttons on the rear fenders to rule out mechanical or hydraulic failures.

3. 3

   Inspect the wiring harness and multi-pin connectors linking the A039 Multifunction Armrest to the basic control unit (EXT) for loose pins, corrosion, or chafing.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts while working on the armrest.

2. 2

   Access the MFA

   Carefully disassemble the A039 Multifunction Armrest housing to access the internal control board and button switches.

3. 3

   Test the Switch

   Use a multimeter to test the continuity of the rear power lift button when pressed.

4. 4

   Replace the Component

   If the button fails the continuity test, replace the individual push-button switch. If the button tests fine but the communication fault persists, the internal bus of the MFA control panel may be defective. In this case, the armrest control module will need to be sent out for repair or replaced entirely.

5. 5

   Reassembly and Calibration

   Reassemble the armrest and reconnect the battery.

6. 6

   Clear Codes and Test

   Perform a cold start. If the entire A039 MFA module was replaced, EOL (End of Line) programming may be required via the FENDIAS diagnostic tool to pair the new armrest with the tractor's basic control unit.