Fendt A.1.D6 – Basic Control Unit (ECU A050) or Enhanced Control ECU (A002): S021 - External 'Raise' pushbutton — No valve operation available

Signal fault or faulty button on the external front power lift 'Raise' switch. The system has detected an electrical anomaly (open circuit, short circuit, or physically stuck button), causing the front power lift to be electronically locked out until the next trouble-free cold start.

• 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 300 Vario (COM III)
• Fendt 400 Vario (COM III) / Farmer 400
• Fendt 500 Vario
• Fendt 700 Vario (COM III) / Favorit 700
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III) / Favorit 900

1. 1

   Inspect the external 'Raise' button (S021) to ensure it is not physically jammed with dirt, mud, or debris.

2. 2

   Perform a key reset/restart (cold start) to see if the fault clears, as the ECU locks the button out upon detecting a fault.

3. 3

   Inspect the wiring harness and electrical connector leading to the S021 switch for breaks, corrosion, or moisture ingress.

4. 4

   Test the switch with a multimeter for continuity to verify if the internal contacts have failed (e.g., stuck closed or open).

5. 5

   Check for related fault codes, such as A.1.D5 for the 'Lower' button (S022), which may indicate a shared ground or harness issue.

1. 1

   Turn off ignition

   Turn off the tractor ignition and remove the key to ensure the ECU is powered down.

2. 2

   Locate switch

   Locate the external front power lift 'Raise' switch (S021) on the front housing of the tractor.

3. 3

   Disconnect harness

   Carefully disconnect the electrical harness connector from the back of the switch.

4. 4

   Remove retaining mechanism

   Remove the retaining mechanism (usually a threaded plastic collar or retaining clips) holding the switch in its mounting panel.

5. 5

   Remove old switch

   Pull the old switch out of the panel. Clean the mounting area and inspect the harness connector for any green corrosion.

6. 6

   Install new switch

   Insert the new OEM switch into the panel and secure it with the retaining collar/clips.

7. 7

   Reconnect harness

   Reconnect the electrical harness, ensuring the weather seal clicks securely into place.

8. 8

   Perform cold start

   Turn the ignition on to perform a cold start. This allows the ECU to run its self-check and clear the A.1.D6 fault code.

9. 9

   Test operation

   Test the external raise function to confirm proper operation.