Fendt 08.1.F3 – A050 - ECU, basic control unit: Y077 - EHR cut-off valve, rear: Overvoltage, safe (where U > 18 V)

The system has detected that the voltage supplied to the rear Electronic Hitch Control (EHR) cut-off valve has exceeded the safe operating threshold of 18 volts. As a safety measure, the valve automatically moves to the neutral position and locks, disabling the rear power lift.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt 300 Vario (COM III)
• Fendt 400 Vario (COM III)
• Fendt 700 Vario (COM III & SCR models)
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III & SCR models)

1. 1

   Measure system voltage at the battery with the engine running (should be 13.5V to 14.5V; readings above 18V indicate an overcharging alternator)

2. 2

   Inspect the wiring harness between the A050 ECU and the Y077 valve for chafed wires that might be shorting the circuit to a higher voltage source

3. 3

   Disconnect the Y077 valve and check the pins for corrosion, water ingress, or bridging

4. 4

   Use a diagnostic tool (FENDIAS or TEXA Navigator) to monitor live voltage data reported by the A050 ECU to identify if the overvoltage is constant or an intermittent spike

1. 1

   Secure the Machine

   Park the tractor on a level surface, lower any attached rear implements to the ground (since the lift is locked out), and turn off the ignition.

2. 2

   Address the Charging System

   If your diagnostic checks revealed an alternator outputting >18V, replace the alternator or the internal voltage regulator.

3. 3

   Repair Wiring

   If the alternator is fine but a short to power was found in the harness leading to the rear EHR valve, splice and repair the damaged section of the wiring harness using weather-sealed connectors.

4. 4

   Replace the Valve

   If the wiring and charging system are perfectly healthy, the Y077 valve's internal solenoid/circuit board may have failed and is misreporting its status. Replace the Y077 EHR cut-off valve.

5. 5

   Clear Codes and Calibrate

   Reconnect all components. Turn the ignition on and use the tractor's terminal or an external diagnostic tool to clear the 08.1.F3 fault code.

6. 6

   Test Operation

   Start the tractor and test the rear power lift functionality to ensure the valve operates smoothly and does not lock into neutral.