Fendt 9.1.C5 – A004 - ECU, control panel: A004 - ECU, control panel; "Lower" quick lift switch - Key fault / Faulty button

The electronic control system has detected an invalid signal, short, or stuck state specifically from the button used to lower the front power lift. As a direct consequence, the front power lift cannot be lowered properly using the in-cab controls.

• 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
• 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
• Fendt Farmer 400 Vario
• Fendt Favorit 700 and 900 Vario
• Fendt 300, 400, 700, 800, and 900 Vario series (including COM III generations)

1. 1

   Inspect the 'Lower' quick lift switch on the A004 control panel for physical damage, sticking, or debris holding the button down

2. 2

   Attempt to lower the front power lift using the external pushbuttons (S022) on the tractor body to isolate the issue to the in-cab switch

3. 3

   Check the tractor's terminal for accompanying CAN bus fault codes (such as 9.1.C6 or 9.1.C0) which may indicate a broader communication failure

4. 4

   Use the FENDIAS diagnostic tool to monitor live data and verify if the ECU is reading the switch as permanently closed (stuck) or open (dead)

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical damage to the A004 control panel.

2. 2

   Access the Console

   Carefully disassemble the A004 control console / multifunction armrest housing to access the internal switch matrix.

3. 3

   Clean and Test

   Clean the switch contacts with electronic contact cleaner. Test the switch continuity with a multimeter.

4. 4

   Component Replacement vs. Console Repair

   If the switch is modular and tests faulty, replace the individual 16V lift/lower switch. Note: If the switch is soldered to the main PCB and cannot be easily desoldered, send the A004 unit to a specialized agricultural electronics repair center (such as Ilgenfritz Mechatronics) for board-level repair.

5. 5

   Reassembly

   Reinstall the switch/console and ensure all wiring harnesses are securely seated.

6. 6

   Clear Codes

   Reconnect the battery, turn on the ignition, and clear the stored 9.1.C5 fault code via the tractor's terminal or FENDIAS software.

7. 7

   Operational Test

   Test the front power lift lowering function to confirm the repair.