Fendt 4.1.77 – A002 ECU: Joystick Acceleration Ramp Switch Faulty

This fault indicates a failure in the A034 drive switch (joystick) specifically related to the acceleration rate selection (ramps I through IV). It points to a communication or hardware issue on the Enhanced Control Bus (CAN-Bus) between the A002 ECU and the joystick. When active, the system defaults to a restricted operating mode where only acceleration rate III is available.

• 409 Vario
• 410 Vario
• 411 Vario
• 412 Vario
• 711 Vario
• 712 Vario
• 714 Vario
• 715 Vario
• 716 Vario
• 717 Vario
• 718 Vario
• 916 Vario
• 920 Vario
• 924 Vario
• 926 Vario
• 930 Vario
• Fendt 300 Vario (COM III)
• Fendt 400 Vario / Farmer 400
• Fendt 700 Vario / Favorit 700
• Fendt 800 Vario
• Fendt 900 Vario / Favorit 900

1. 1

   Connect the FENDIAS diagnostic program to read the active fault and monitor the live inputs from the A034 drive switch.

2. 2

   Check the CAN-Bus connection between the A002 ECU and the A034 Joystick for damaged wires, loose connector pins, or corrosion.

3. 3

   Inspect the acceleration ramp buttons on the joystick for physical damage, sticking, or dirt ingress.

1. 1

2. 2

   Disconnect power

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

3. 3

   Access the joystick

   Carefully remove the armrest trim to access the A034 joystick wiring harness and mounting hardware.

4. 4

   Inspect and repair wiring

   If diagnostics reveal a wiring fault on the Enhanced Control Bus, repair the damaged section of the harness or replace the connector pins.

5. 5

   Repair or replace joystick components

   If internal electronics or switches are dead, replace the specific switch plate/buttons, send the unit to a specialized repair service, or replace the entire A034 joystick assembly.

6. 6

   Reassemble components

   Install the repaired or new joystick and reconnect the wiring harness.

7. 7

   Perform EOL programming

   If a new joystick is installed, run a new EOL (End of Line) programming/initialization for the A034 joystick using the FENDIAS diagnostic tool to pair it with the tractor's ECU.

8. 8

   Clear codes and test

   Clear the fault codes and test the tractor to ensure all acceleration ramps (I-IV) are functioning correctly.