Fendt 4.1.28 – Transmission Control Unit (TCU): Transmission control unit, F/R (Forward/Reverse) incremental encoder — Signal fault

The system has detected a signal failure or faulty path signal from the incremental encoder located within the transmission actuator unit. The tractor will lose standard transmission control, but continuation in emergency mode is possible.

• 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
• 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)
• 309
• 310
• 311
• 312
• Fendt Farmer 400
• Fendt 400 Vario (COM III)
• 409
• 410
• 411
• 412
• Fendt Favorit 700
• Fendt 700 Vario (COM III)
• 711
• 712
• 714
• 716
• 717
• Fendt 800 Vario (COM III)
• 815
• 817
• 818
• Fendt Favorit 900
• Fendt 900 Vario (COM III)
• 916
• 920
• 924
• 926
• 930
• 933
• 936
• 939

1. 1

   Access 'Diagnostics Menu 1' on the Variotronic terminal and compare IDEAL, VE, and REAL values to confirm if the VE signal is missing or erratic

2. 2

   Inspect the wiring harness connecting to the A009 actuator unit for chafed wires, corrosion, or loose connections

3. 3

   Verify the CAN bus terminating resistors at the A013 circuit board and A009 actuator unit to rule out network communication errors

4. 4

   Check the ease of movement of the adjustment device using the emergency control system to ensure the actuator isn't mechanically jammed

1. 1

   Engage Emergency Mode

   If the tractor is in the field, use the emergency transmission control mode to safely move the tractor to the workshop.

2. 2

   Access the Actuator

   Locate the A009 actuator unit on the Vario transmission housing.

3. 3

   Disconnect Power

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

4. 4

   Remove the A009 Unit

   Disconnect the electrical harness from the A009 actuator unit. Unbolt and carefully remove the actuator unit from the transmission.

5. 5

   Replace the Component

   Depending on parts availability, replace the entire A009 actuator unit (which houses the incremental encoder, 12V DC electric motor, 192:1 planetary gear, and slip clutch).

6. 6

   Reinstallation & Calibration

   Install the new actuator unit and reconnect the harness.

7. 7

   Initialization

   Turn the ignition ON. The A009 actuator unit must automatically locate its initial reference point (zero position). Do not start the engine or move the joystick until this initialization is complete.

8. 8

   Clear Codes

   Use the terminal to clear the 4.1.28 fault code from the memory and test drive to verify the 'VE' and 'REAL' values match.