Fendt 04.1.26 – A039 / A100 (MFA - Multifunction Armrest): Accelerator pedal mode button signal fault

The system detects that the Accelerator pedal mode button is faulty or sending an incorrect signal, causing the throttle pedal mode to become inoperable.

• 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 and SCR)
• Fendt 800 Vario (COM III and SCR)
• Fendt 900 Vario (COM III, S4, and SCR models like 916, 920, 922, 924, 927, 930, 933, 936)

1. 1

   Visually inspect the connection between the armrest control panel and the main armrest controller for damaged wires, loose connections, or bent pins in the harness.

2. 2

   Open the armrest controller housing, disconnect the connector for the joystick/button panel, and test the continuity of the accelerator pedal mode button when pressed and released.

3. 3

   Turn the tractor key switch to the ACC position and verify that the armrest controller is receiving the correct reference voltage (typically 8V or 12V).

4. 4

   Run the armrest controller calibration procedure to see if the communication error can be resolved without parts replacement.

1. 1

   Disconnect Power

   Turn off the tractor ignition and disconnect the battery ground to prevent electrical shorts.

2. 2

   Access the MFA

   Carefully remove the cover panels on the multifunction armrest to expose the internal wiring and the base of the joystick/button modules.

3. 3

   Inspect and Clean

   Disconnect the main harness connectors (e.g., J2 connector). Clean the contacts with electrical contact cleaner and reconnect them to rule out a simple poor connection.

4. 4

   Replace the Faulty Component

   If the continuity test proves the accelerator pedal mode button is dead, replace the joystick assembly or the specific button plate (depending on the exact modularity of your tractor's armrest).

5. 5

   Reassemble and Calibrate

   Install the new joystick or armrest module. Reconnect the battery, turn on the ignition, and use the tractor's terminal to clear the stored 04.1.26 fault code.

6. 6

   Test Operation

   Engage the accelerator pedal mode to verify that the throttle pedal is now operable and the fault does not return.