Fendt 9.3.17 – Front EPC (Electronic Power Control / Front Power Lift) control module: Battery — Supply voltage > 18 volt.

The system is detecting an overvoltage condition where the electrical supply voltage has exceeded 18 volts. The system terminates operation and triggers a 'Control locked' state to protect the electronics from overvoltage damage.

• 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 Vario
• Favorit 700 Vario
• Favorit 900 Vario
• 300 Vario series
• 400 Vario series
• 700 Vario series
• 800 Vario series
• 900 Vario series
• 927 Vario
• 933 Vario
• 936 Vario
• 939 Vario

1. 1

   Use a multimeter at the battery terminals while the engine is running. A healthy 12V system should read between 13.8V and 14.4V. If it reads above 18V, the alternator is overcharging.

2. 2

   If the voltage is too high, check the alternator's internal voltage regulator, which has likely failed and is no longer capping output voltage.

3. 3

   Check the 'Ub 30' circuit (Circuit 30 / constant battery power) feeding the Front EPC control module for shorts to a higher voltage source.

4. 4

   Verify that the tractor was not recently jump-started incorrectly using a 24V system, which would immediately trigger this >18V code.

5. 5

   Check the tractor's terminal to see if other ECUs are also reporting overvoltage codes. If multiple modules report it, the issue is definitively the main charging system.

1. 1

   Disconnect Power

   Immediately turn off the tractor and disconnect the battery to prevent the >18V supply from frying the Front EPC ECU or other sensitive control modules.

2. 2

   Replace the Voltage Regulator / Alternator

   If the alternator was outputting >18V during the diagnostic check, remove the alternator. Depending on the exact model, either replace the bolt-on voltage regulator on the back of the alternator or replace the entire alternator assembly.

3. 3

   Inspect and Reconnect

   Inspect the wiring harness leading to the Front EPC for any melted insulation caused by the overvoltage. Reconnect the battery.

4. 4

   Verify Charging Voltage

   Start the tractor and verify with a multimeter that the charging voltage is now stable at around 14.1V.

5. 5

   Clear Fault Codes

   Access the tractor's terminal/dashboard. Navigate to the fault memory menu and clear the stored 9.3.17 code individually, as canceling a fault message from the display does not remove it from the ECU's memory.

6. 6

   Test Operation

   Test the Front Power Lift (Front EPC) to ensure the 'Control locked' state has been lifted and normal hydraulic operation has resumed.