Fendt 0A.1.D0 – A039 (or A100) Multifunction Armrest (MFA) module: A039 (or A100) - MFA, multifunction armrest: Button, hydraulic circuit 3

The system has detected an implausible signal from the button that controls hydraulic circuit 3 (often caused by a stuck button, internal microswitch failure, or a short/break in the signal line), rendering it 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 900 Vario series
• 919
• 922
• 925
• 928
• 931
• 934
• Fendt 300 Vario series (COM III)
• Fendt 400 Vario series
• Fendt 700 Vario series
• Fendt 800 Vario series

1. 1

   Perform a Cold Start: Turn the tractor completely off, let the systems power down, and restart the machine to see if it was a temporary glitch.

2. 2

   Physical Inspection: Inspect the hydraulic circuit 3 button on the multifunction armrest for sticky residue, dirt, or physical damage causing it to stick.

3. 3

   Wiring and Signal Line Check: Lift the armrest console and inspect the wiring harness connecting the MFA to the main cab harness for pinched wires, chafing, or loose connector pins.

4. 4

   Multimeter Testing: Back-probe the switch connector to test the button's electrical continuity and verify the switch properly opens and closes the circuit.

1. 1

   Disconnect Power

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

2. 2

   Access the MFA Internals

   Remove the retaining screws on the underside or perimeter of the multifunction armrest to carefully lift the top cover/keypad area.

3. 3

   Isolate the Switch

   Locate the specific switch assembly for hydraulic circuit 3.

4. 4

   Replace the Component

   If the button is a modular, replaceable microswitch: Unplug its connector, unclip it from the housing, and snap the new switch into place. If the button is integrated into a printed circuit board (PCB) or the main joystick assembly: The entire MFA sub-assembly or circuit board will need to be replaced.

5. 5

   Reassemble

   Reconnect all wiring harnesses, ensuring they are routed correctly so they do not get pinched when the armrest is closed. Secure the armrest cover with its screws.

6. 6

   Test and Clear

   Reconnect the battery. Turn the key on and perform a cold start. Test hydraulic circuit 3 to ensure functionality has returned and the 0A.1.D0 code has cleared.