Fendt 9.1.C2 – A004 - ECU, Control Panel: A004 - ECU, control panel; Valve locking. Key fault / Faulty button.

Mechanical or electrical failure of the 'Valve locking' button located on the tractor's main operating console. The button's signal is either missing, stuck, or shorted. As a consequence, the system disables the overall locking of the hydraulic valves, and the Front Power Lift (front hitch) may experience restricted functionality.

• 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 409
• Fendt Farmer 400 Vario 410
• Fendt Farmer 400 Vario 411
• Fendt Farmer 400 Vario 412
• Fendt Farmer 400 Vario 415
• Fendt Favorit 700 Vario 711
• Fendt Favorit 700 Vario 712
• Fendt Favorit 700 Vario 714
• Fendt Favorit 700 Vario 716
• Fendt Favorit 700 Vario 718
• Fendt 800 Vario 820
• Fendt Favorit 900 Vario 916
• Fendt Favorit 900 Vario 918
• Fendt Favorit 900 Vario 920
• Fendt Favorit 900 Vario 924
• Fendt Favorit 900 Vario 926
• Fendt Favorit 900 Vario 930

1. 1

   Inspect the 'Valve locking' button on the A004 console for physical damage, sticking, dirt ingress, or a collapsed membrane that prevents the button from returning to its neutral position.

2. 2

   Switch the tractor's ignition OFF and then back ON to see if the fault resets, as temporary voltage spikes can trigger a false key fault.

3. 3

   Verify the voltage supply to the CAN bus by checking fuses F039, F040, F041, and F046 on the A013 fuse board to ensure the console is receiving proper power.

4. 4

   Use the FENDIAS diagnostic tool to monitor the digital inputs of the A004 console and check if the valve locking button is registering a permanent 'pressed' state or no state at all.

1. 1

   Disconnect battery

   Disconnect the tractor's battery to prevent electrical shorts.

2. 2

   Remove trim pieces

   Carefully remove the trim pieces surrounding the right-hand armrest to access the A004 control console mounting hardware.

3. 3

   Remove console

   Remove the retaining screws and carefully lift the A004 console out of the armrest.

4. 4

   Inspect wiring harnesses

   Disconnect the multi-pin wiring harnesses from the bottom of the unit. Inspect the harness connectors for bent pins or corrosion.

5. 5

   Repair or replace console

   Install a new or known-good OEM A004 control console, or send the defective console to a specialized agricultural electronics repair center to rebuild the internal keypad membrane, replace faulty microswitches, and repair EEPROM failures.

6. 6

   Reconnect console

   Reconnect the wiring harnesses to the repaired/new console and secure it back into the armrest.

7. 7

   Reconnect battery

   Reconnect the battery and turn on the ignition.

8. 8

   Clear fault code and test

   Connect the FENDIAS diagnostic tool, clear the 9.1.C2 fault code, and test the valve locking button to ensure full hydraulic functionality has returned.