Fendt 01.1.7C – A039 (or A100) - MFA (Multifunction Armrest): A039 - MFA, multifunction armrest TMS button

An electrical fault specifically with the TMS (Tractor Management System) button, which causes the TMS to be automatically switched off by the 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 900 Vario (COM III and SCR models)
• Fendt 700 Vario (COM III and SCR models)
• Fendt 300 Vario series
• Fendt 400 Vario series
• Fendt 800 Vario series

1. 1

   Turn the ignition off and back on to see if the system resets from a temporary communication glitch.

2. 2

   Check the wiring harness leading to the armrest, specifically looking for a broken wire located just an inch or two below the main plug.

3. 3

   Use the terminal to scroll through active faults to see if multiple buttons are failing (e.g., cruise control buttons MIN/MAX logging 01.1.9A or 01.1.9B), which would indicate a CAN bus communication failure or a completely dead armrest board rather than a single faulty TMS button.

1. 1

   Clear and Verify

   Attempt to clear the fault code via the terminal. Note that cancelling a fault code only removes it from the display; each stored fault code must be cleared individually, and it will return on the next startup if the hard fault remains.

2. 2

   Harness Repair

   Access the armrest wiring harness. If a broken wire is found near the connector plug, splice and repair the connection.

3. 3

   Component Testing

   If the wiring is intact, test the continuity of the TMS button itself. If the button has failed mechanically or electrically, it must be replaced.

4. 4

   Board Repair/Replacement

   If the button is fine but the armrest control board is defective, the board must be removed. Send the armrest control panel to specialized agricultural electronics repairers to test and repair the internal circuitry.

5. 5

   Calibration

   If a new or second-hand armrest board is installed, use Fendt/AGCO diagnostic software to program the new board and calibrate the remote levers and hitch controls.