Fendt 08.1.4B – A039 / A100 Multifunction Armrest (MFA): Button, auto rear power lift (Rear power lift auto button)

The system has detected a 'Faulty button (output via Teach-in)' or a 'Switch actuation/timeout time' error. This typically means the button for the automatic rear power lift on the multifunction armrest is sending an invalid signal, is electrically shorted/open, or is physically stuck in the depressed position causing a timeout, which disables the automatic mode.

• 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 200 V/F/P Vario
• FENDT 300 Vario (COM III)
• FENDT 400 Vario (COM III)
• FENDT 700 Vario (COM III)
• FENDT 700 SCR series
• FENDT 800 Vario (COM III)
• FENDT 800 SCR series
• FENDT 900 Vario (COM III)
• FENDT 900 SCR series
• 916
• 920
• 922
• 924
• 927
• 930
• 933
• 936

1. 1

   Inspect the auto rear power lift button on the multifunction armrest for dirt, debris, or sticky residue causing it to physically stick.

2. 2

   Press and release the button several times with the tractor off to see if the tactile click returns and the switch un-sticks.

3. 3

   Connect the FENDIAS diagnostic tool to monitor live data of the A039/A100 module and check if the button state reads as permanently 'Active' or 'Invalid'.

4. 4

   Test the A039 MFA using the Fendt 160-pin adapter box to verify if the switch is outputting the correct voltage/resistance when actuated.

5. 5

   Verify the wiring harness and connectors between the A039 MFA and the A050 Basic Control Unit for any signs of chafing or poor pin tension.

1. 1

   Clean the Keypad

   If the button is physically sticking, use a plastic safe electronic contact cleaner (like CRC QD Contact Cleaner) around the edges of the button. Work the button repeatedly to free up the mechanism.

2. 2

   Clear Codes

   Turn the tractor on and use the Varioterminal or FENDIAS to clear the 08.1.4B fault code. Test the rear power lift auto function.

3. 3

   Disassemble the Armrest

   Power down the tractor and disconnect the battery. Remove the retaining screws on the underside of the multifunction armrest to access the internal membrane/switch board.

4. 4

   Replace the Component

   If the switch has failed internally on the PCB, the keypad membrane or the entire A039 MFA top module must be replaced.

5. 5

   Reassembly and EOL Programming

   Install the new armrest module or keypad. Reconnect the battery. Note: If the entire A039 MFA module is replaced, End of Line (EOL) programming via FENDIAS is required to introduce the new module to the tractor's CAN bus system.

6. 6

   Calibration

   Perform a Teach-in calibration for the rear power lift controls to ensure the new button inputs are recognized by the A050 ECU.