Fendt A.1.DD – EHR (Electronic Hitch Control) / Enhanced Control ECU: S021, S022 - External button 'raise' / 'lower' — Button double operation (button possibly stuck)

The system is detecting a continuous, simultaneous, or conflicting electrical signal from the external front power lift control buttons (S021 for 'raise' and S022 for 'lower'). The system assumes the button is physically stuck, jammed, or internally shorted, which locks out the valves and prevents the front power lift from being lowered properly.

• 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
• 900 Vario Series (916, 920, 924, 926, 930, 933)
• 700 Vario Series
• 400 Vario Series
• 800 Vario Series
• 300 Vario Series

1. 1

   Inspect the external front power lift buttons (S021 and S022) for physical damage, packed mud, ice, or debris that might be physically holding the button down.

2. 2

   Disconnect the switch and use a multimeter to test for continuity. Verify that the switch circuit is open when unpressed and closed only when pressed.

3. 3

   Inspect the wiring harness and connectors leading from the external buttons to the EHR control module for chafed wires that might be shorting to ground or to each other.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Clean the Area

   Thoroughly clean the housing around the external front power lift switches. Sometimes, simply clearing out packed dirt or agricultural debris will unstick the button and resolve the fault.

3. 3

   Remove the Faulty Switch

   If the switch is internally failed, access the rear of the switch housing. Disconnect the 2-pin electrical connector from the back of the switch.

4. 4

   Dismount

   Squeeze the retaining tabs or remove the mounting screws (depending on the exact model year) to pop the faulty switch out of its mounting bracket.

5. 5

   Install the New Switch

   Push the new OEM replacement switch into the housing until it clicks into place. Apply a small amount of dielectric grease to the electrical contacts to prevent future moisture corrosion, then plug in the wiring harness.

6. 6

   Clear Codes and Test

   Reconnect the battery and start the tractor. Use the Fendt Vario terminal to navigate to the fault display menu and clear the stored A.1.DD fault code. Test the front power lift using both the in-cab controls and the newly installed external buttons to ensure full functionality is restored.