Fendt 4.1.A6 – Transmission Control Unit (TCU) / A009 Actuator Unit: Transmission control unit — Reference point signal fault during operation.

The A009 transmission control unit (actuator unit) has lost its reference point (zero position) or received an incorrect/implausible signal from the incremental encoder during operation. The system cannot accurately verify the actual transmission adjustment (REAL position) against the target value (IDEAL position). The tractor will default to auxiliary/emergency operation mode, locking the transmission at a maximum speed of approximately 30 km/h.

• 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 series
• Favorit 700 and 900 series
• 300, 400, 700, 800, and 900 Vario series (including COM III and SCR generations)

1. 1

   Use the emergency control system to manually check the ease of movement of the transmission adjustment device to rule out a mechanical bind.

2. 2

   Inspect the physical connection between the A009 actuator unit and the transmission actuator shaft for looseness.

3. 3

   Check the B014 accumulator shaft sensor (incremental encoder) which provides feedback for the actual transmission adjustment.

4. 4

   Check the CAN-bus wiring to the transmission control unit and verify the power supply on the A013 circuit board (specifically check microfuses F040 and F041).

1. 1

   Depressurize the System

   Ensure the tractor is off. If the clutch pedal, handbrake, or neutral switch is operated, the high-pressure circuit is depressurized by means of the two high-pressure-relief valves.

2. 2

   Access the Actuator

   Locate the A009 actuator unit on the transmission control housing.

3. 3

   Remove the Actuator Shaft

   Carefully dismantle the control housing and remove the actuator shaft to free the A009 unit.

4. 4

   Replace the Component

   Install the new A009 actuator unit (and/or the B014 sensor if the encoder track is faulty).

5. 5

   Reassembly

   Refit the actuator shaft, connecting rod, and control housing. Top up the transmission oil (STOU 10W-40) if any was lost during the procedure.

6. 6

   Calibration / Teach-In

   Connect the FENDIAS diagnostic tool. You must perform an EOL (End of Line) programming or Teach-In procedure to calibrate the new actuator unit so the ECU can learn the new reference/zero points for forward and reverse.