Fendt 4.1.A4 – Transmission Control Unit: A009 - Actuator unit. Fault or logical error in EST signal

The transmission control unit is receiving an invalid, missing, or illogical signal from the EST track (the incremental position sensor) of the A009 transmission actuator unit. When the ignition is switched on, the actuator unit searches for a reference point (the neutral point between forward and reverse). If the signal is faulty, the tractor will default to auxiliary/emergency operation mode.

• 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
• Farmer 400 series
• Favorit 700 series
• Favorit 900 series
• Fendt 300 Vario series
• Fendt 400 Vario series
• Fendt 500 Vario series
• Fendt 700 Vario series
• Fendt 800 Vario series
• Fendt 900 Vario series
• Fendt 1000 Vario series
• 312
• 512
• 724
• 828
• 930
• 936
• 1050

1. 1

   Perform a key reset by turning the ignition OFF, waiting a few seconds, and turning it back ON to clear potential calibration exit faults

2. 2

   Engage the emergency operation mode manually using the socket wrench to verify the transmission control runs smoothly without binding (slip clutch should require less than 5 Nm of torque)

3. 3

   Inspect the wiring harness, CAN bus connections, and terminating resistors between the Transmission ECU and the A009 Actuator Unit for breaks, corrosion, or short circuits

4. 4

   Consult the transmission control system circuit diagram to test the EST track signal pins directly at the A009 connector

1. 1

   Park the tractor on a level surface, apply the handbrake, and turn the ignition OFF.

2. 2

   Locate the A009 Actuator Unit on the transmission control housing.

3. 3

   Disconnect the electrical harness connected to the actuator unit.

4. 4

   Unbolt and remove the faulty A009 actuator unit from the transmission housing.

5. 5

   Install the new A009 actuator unit and torque the mounting bolts to OEM specifications.

6. 6

   Reconnect the electrical harness.

7. 7

   Connect the FENDIAS diagnostic tool and perform an EOL (End of Line) programming/calibration.

   This allows the new actuator to learn its reference points (precise neutral point between forward and reverse travel).