Fendt 4.1.A0 – Transmission Control Unit (A009 Actuator Unit): Actuation fault in transmission control module

This code indicates that the transmission actuator unit is failing to control the specified transmission ratio value exactly, or there is a mechanical/electrical fault preventing the actuator from moving the transmission adjustment shaft properly. When this code is active, the tractor will typically default to auxiliary/emergency operation 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
• 300 Vario (COM III, S4, SCR)
• 400 Vario / Farmer 400
• 500 Vario (S4, SCR)
• 700 Vario / Favorit 700
• 800 Vario
• 900 Vario / Favorit 900 (COM III, S4, etc.)
• 1000 Vario series

1. 1

   Mechanical Verification (Emergency Mode): Check the ease of movement of the adjustment device using the emergency control system. If the mechanical adjustment is stiff or binding, the issue may be internal to the transmission rather than the electronic actuator.

2. 2

   Inspect the Linkage: Check the physical connection between the A009 actuator unit and the transmission actuator shaft. Ensure it is secure and not stripped or loose.

3. 3

   Electrical/CAN Bus Checks: Check the transmission bus terminating resistors located on the A013 circuit board and the A009 actuator unit. Ensure the wiring harness supplying the A009 unit is intact and free of corrosion.

4. 4

   Check for Smooth Adjustment: Using the Variotronic terminal or FENDIAS diagnostic tool, monitor the IDEAL (target value) vs. VE (feedback from the incremental encoder) vs. REAL (actual transmission adjustment) values to see where the discrepancy occurs.

1. 1

   Access the Actuator

   The A009 actuator unit is located on the right side of the tractor, mounted directly on the transmission housing. To gain access, safely support the tractor, remove the right rear wheel, and remove the side access panel.

2. 2

   Removal

   Disconnect the electrical harness from the A009 unit. Unbolt the actuator unit from the transmission housing and carefully slide it off the actuator shaft.

3. 3

   Installation

   Install the new A009 actuator unit onto the actuator shaft, ensuring the splines/connection seat correctly. Torque the mounting bolts to OEM specifications and reconnect the electrical harness.

4. 4

   Calibration

   After replacing the A009 unit, you must use the FENDIAS diagnostic tool or the tractor's onboard terminal to clear the fault codes and perform a transmission calibration procedure (teaching the new actuator the neutral, forward, and reverse reference points).