Fendt 4.1.2F – A002 (Enhanced Control ECU) or A050 (Basic Control Unit): A034 - Driving switch, CAN bus: 'v- transmission adjustment' (joystick to rear) - Signal fault.

Signal failure or data transfer error on the CAN bus originating from the A034 driving switch (the main multifunction joystick) when it is pulled backward (the 'v-' command for decelerating or reversing transmission adjustment). The tractor will typically restrict normal operation, but continuation in emergency mode is possible.

• 411 Vario COM III
• 412 Vario COM III
• 413 Vario COM III
• 414 Vario COM III
• 415 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
• 718 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• Fendt 300 Vario (COM III)
• Fendt 400 Vario (COM III) (Models 409, 410, 411, 412)
• Fendt 700 Vario (COM III) (Models 711, 712, 714, 716)
• Fendt 800 Vario (COM III) (Models 815, 817, 818)
• Fendt 900 Vario (COM III) (Models 916, 920, 924, 926, 930)

1. 1

   Check the 8.5V power supply to the joystick and inspect fuses on circuit board A013 (specifically F040, F041, F047, and Fuse 16)

2. 2

   Consult wiring diagram Sheet 29 (or Sheet 22/6 depending on the model) and inspect the wiring harness between the A034 joystick and the A002 ECU for chafing, pinched wires, or loose connector pins

3. 3

   Connect the FENDIAS diagnostic tool to read A034 joystick data, checking for a signal from the 'v-' axis, CAN bus error counter overflows, or EOL checksum errors

1. 1

   Secure the Tractor

   Park the tractor on a level surface, engage the parking brake, and turn off the ignition.

2. 2

   Verify Power

   Access circuit board A013 and test the aforementioned fuses. Replace any blown fuses and test the joystick operation again.

3. 3

   Test the Connection

   Remove the armrest covers to access the base of the A034 joystick. Disconnect the joystick connector and check for corrosion or bent pins. Clean with contact cleaner and reconnect.

4. 4

   Replace the Joystick

   If the wiring and voltages are correct but the 'v-' signal is still failing (or if the joystick physically fails to register the backward pull), remove the mounting screws for the joystick assembly, disconnect the CAN harness, and install the new A034 joystick.

5. 5

   EOL Programming / Calibration

   Use the FENDIAS diagnostic program to run a new EOL (End of Line) programming sequence to teach-in the new A034 driving switch to the A002 ECU.

6. 6

   Clear Codes

   Clear the fault memory and test drive the tractor to ensure the 'v-' transmission adjustment works smoothly without throwing the 4.1.2F code.