Fendt 9.1.D0 – Enhanced Control Unit (ECU A002): S021 - 'Lift' (or 'Raise') front power lift external pushbutton — Key fault.

An electrical or mechanical fault with the external button used to raise the front power lift. The system detects a 'Key fault' (button stuck closed, shorted, or broken signal line), causing the front power lift to become non-operational via external 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
• Farmer 400 series
• Favorit 700 series
• Favorit 900 series
• 300 Vario series
• 400 Vario series
• 500 Vario series
• 700 Vario series
• 800 Vario series
• 900 Vario series
• 916
• 920
• 924
• 926
• 930
• 933
• 936
• 939

1. 1

   Inspect the S021 external 'Raise' pushbutton for physical damage, packed dirt, or debris that might be holding the button down.

2. 2

   Trace the wiring harness from the S021 switch back to the main harness. Look for breaks, chafing, or corrosion at the connector.

3. 3

   Disconnect the switch and test it with a multimeter. Check for continuity when the button is pressed and an open circuit when released. If the switch shows continuity without being pressed, it is stuck closed and must be replaced.

4. 4

   Verify the signal lines on the 'Spool valves 2' circuit diagram to ensure the ECU is receiving the correct voltage.

1. 1

   Turn off the tractor, engage the parking brake, and disconnect the battery to ensure electrical safety.

2. 2

   Locate the S021 external 'Raise' pushbutton on the front power lift housing.

3. 3

   Reach behind the mounting panel and disconnect the electrical connector from the switch.

4. 4

   Clean the harness connector and inspect for moisture or corrosion. Apply dielectric grease to prevent future corrosion.

5. 5

   If the switch failed the diagnostic continuity test, unclip or unscrew the retaining collar holding the switch to the mounting panel and remove the faulty switch.

6. 6

   Install the new S021 pushbutton switch into the mounting hole and secure it.

7. 7

   Reconnect the wiring harness to the new switch.

8. 8

   Reconnect the battery and turn on the tractor ignition.

9. 9

   Clear the stored fault codes from the tractor's terminal.

10. 10

    Test the front power lift operation using the external 'Raise' button to confirm the repair is successful.