Fendt 4.1.23 – Transmission Control Unit (TCU): A003, A034 - Joystick 'cruise control ON' — Signal fault

The system has detected a signal failure, implausible signal, or out-of-range signal from the 'Cruise Control ON' button (A003) located on the Vario drive joystick (A034). When active, cruise control will be unavailable, but the tractor can continue to be driven in emergency/auxiliary mode.

• 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
• Farmer 400 Vario
• Favorit 700 Vario
• Favorit 900 Vario
• Fendt 300, 400, 700, 800, and 900 Vario series (including COM III generation models)

1. 1

   Use the FENDIAS diagnostic software or the tractor's onboard terminal A008 (Variotronic Ti) to monitor the live signal of the joystick buttons. Check if the ECU registers a signal when the 'Cruise Control ON' button is pressed.

2. 2

   Check the wiring harness and connectors between the joystick (A034) and the side console/transmission control unit. Look for wire disruptions, short circuits, or loose pins.

3. 3

   Verify the voltage supply to the joystick. The joystick typically relies on an 8.5V supply. Check the A013 fuse board (specifically fuses related to the joystick CAN bus, such as F047) to ensure the circuit is receiving proper power.

4. 4

   Isolate the component: If other joystick functions (like rapid reverse or auxiliary valves) are also failing, the issue is likely a CAN bus communication failure or a completely failed joystick circuit board. If only the cruise control button fails, the physical switch/button on the joystick is likely defective.

1. 1

   Power Down

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

2. 2

   Access the Joystick

   Carefully remove the side console trim to access the base and wiring of the Vario joystick (A034).

3. 3

   Component Replacement

   If only the button is broken: On some models, the individual joystick switch plate or the color-coded buttons can be replaced without discarding the whole joystick. If the internal circuit is faulty: Disconnect the joystick's main electrical connector and remove the entire joystick assembly from the armrest. Install the new OEM joystick.

4. 4

   Reassembly

   Reconnect the wiring harness and secure the joystick and console trim.

5. 5

   EOL Programming

   Reconnect the battery and turn on the ignition. If the entire joystick (A034) was replaced, you must run a new EOL (End of Line) programming/calibration using the FENDIAS tool so the ECU recognizes the new joystick.

6. 6

   Testing

   Clear the stored fault codes and perform a test drive to verify that the cruise control function engages properly.