Fendt 08.1.46 – A039 - MFA, multifunction armrest: Faulty button, signal fault (Control button, SAH rear power lift)

Indicates a 'Faulty button, signal fault' specifically related to the Control button, SAH rear power lift. When this signal fault is detected, the system's safety protocol renders the 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
• Fendt 400 Vario
• Fendt 700 Vario
• Fendt 800 Vario
• Fendt 900 Vario
• Fendt 916
• Fendt 920
• Fendt 922
• Fendt 924
• Fendt 926
• Fendt 927
• Fendt 930
• Fendt 933
• Fendt 936

1. 1

   Perform a cold start reset by turning the ignition OFF, waiting briefly, and turning it back ON to see if the fault clears or is a hard failure.

2. 2

   Verify if the rear power lift can still be operated externally via the fender buttons to isolate the issue to the armrest button/wiring.

3. 3

   Inspect the wiring harness and connectors between the A039 multifunction armrest and the A050 basic control unit for pinched wires, corrosion, or loose pins.

4. 4

   Test the A039 armrest using a 160-pin adapter box to verify the electrical resistance and signal output of the specific button.

1. 1

   Disconnect Power

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

2. 2

   Access the Armrest Internals

   Carefully remove the covers of the Grammer seat console/multifunction armrest to access the internal button matrix and wiring.

3. 3

   Test/Replace the Switch

   If the wiring harness tests fine with the 160-pin adapter but the button signal is still faulty, the physical switch has failed internally.

4. 4

   Component Replacement

   Depending on the exact armrest revision, you may be able to solder/plug in a replacement push button switch. If the button is integrated into a sealed printed circuit board (PCB) within the armrest, the entire A039 multifunction armrest control module must be replaced.

5. 5

   Reassembly and Calibration

   Reassemble the armrest. If the entire A039 module was replaced, an EOL (End of Line) programming/calibration via the Fendt terminal may be required to pair the new armrest with the A050 basic control unit.

6. 6

   Clear Codes

   Perform a cold start and clear the stored fault codes from the tractor's memory.