Fendt 4.1.88 – Transmission ECU: Plausibility error at the ON / OFF key of the accelerator pedal mode

The system is receiving an invalid, illogical, or missing signal from the specific button on the joystick that engages the accelerator pedal drive mode. The key stops functioning, and the tractor can no longer be operated in accelerator pedal mode (only manual/joystick adjustment 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
• 411 Vario
• 412 Vario
• 413 Vario
• 414 Vario
• 415 Vario
• 711 Vario
• 712 Vario
• 714 Vario
• 716 Vario
• 718 Vario
• 724 Vario
• 815 Vario
• 817 Vario
• 818 Vario
• 820 Vario
• 916 Vario
• 920 Vario
• 924 Vario
• 926 Vario
• 930 Vario

1. 1

   Check the ON/OFF button on the joystick for physical damage, sticking, or debris preventing it from making a clean contact

2. 2

   Verify the power supply for the CAN bus in circuit board A013. Specifically, check fuse F047 (Joystick CAN bus power supply)

3. 3

   Connect the FENDIAS diagnostic program to check the live data of the A034 drive switch to see if the button press is registering at all

4. 4

   Inspect the wiring harness and CAN bus connections between the A034 Joystick and the Transmission control unit for continuity, shorts, or corrosion

1. 1

   Clear the Code

   Attempt to clear the fault message via the terminal. Each stored fault message must be cleared individually (press and hold the key, then press the button). If the code immediately returns, hardware repair is required.

2. 2

   Button Replacement

   If the button itself is physically broken but the internal board is fine, carefully pop out the old button and snap in a replacement ABS plastic button (often sold in aftermarket Red/Green sets).

3. 3

   Joystick Repair/Replacement

   If the button is mechanically sound but fails plausibility checks, the joystick's internal CAN circuit board is likely defective. Remove the drive lever and send it to an agricultural electronics specialist for a CAN circuit board repair, or replace the entire A034 Joystick / Switch Plate assembly.

4. 4

   Reprogramming

   If the entire joystick or the ECU is replaced, run a new EOL (End of Line) programming procedure using the FENDIAS tool to pair the new hardware with the tractor's CAN bus network.