Fendt 08.1.16 – A024 - ECU, EPC B: ECU, EPC B – Ub_Stab / sensor supply

There is a fault with the stabilized voltage supply (Ub_Stab) going from the ECU to the sensors on the rear power lift circuit. This usually indicates a short circuit, an open circuit, or a failed sensor pulling the reference voltage down, resulting in 'Control locked' where the electrohydraulic lifting gear control is disabled.

• 309 Vario COM III
• 310 Vario COM III
• 311 Vario COM III
• 312 Vario COM III
• Fendt 300 Vario COM III (Models 309, 310, 311, 312)
• Fendt 400 Vario COM III (Models 411, 412, 413, 414, 415)
• Fendt 700 Vario COM III (e.g., 712)
• Fendt 800 Vario COM III
• Fendt 900 Vario COM III

1. 1

   Measure the stabilized voltage output directly from the A024 ECU to the rear hitch sensors.

2. 2

   Unplug the sensors on this circuit one by one (B030, B031, B032, A035) to see if the voltage returns to normal, isolating a potentially shorted sensor.

3. 3

   Inspect the wiring harness between the A024 ECU (Connector X850) and the sensors for chafing, pinched wires, or corrosion that could cause a short to ground.

4. 4

   Check power and ground to the ECU to ensure the A024 module is receiving proper battery voltage and has a clean ground connection.

1. 1

   Access the ECU and Harness

   Locate the A024 EPC B ECU and the rear power lift sensor harness.

2. 2

   Test and Repair Wiring

   If a short to ground is found in the harness during the diagnostic phase, repair the damaged wire and clear the fault code.

3. 3

   Replace Faulty Sensor

   If unplugging a specific sensor (e.g., the B030 position sensor or a draft pin) restores the stabilized voltage, replace that sensor.

4. 4

   Replace the ECU (if necessary)

   If the wiring is intact, no sensors are shorted, and the ECU is still failing to output the stabilized sensor voltage, the A024 ECU has an internal failure and must be replaced.

5. 5

   Calibration

   If the A024 ECU or any of the sensors (B030, A035) are replaced, you must perform an EOL (End of Line) programming and calibration procedure using the FENDIAS diagnostic tool. You will need to run the Rear EPC calibration code 8001 (for the setpoint potentiometer) and 8002 (for the position sensor) to restore functionality.