Fendt 0A.1.D4 – Hydraulics ECU: S021 - Switch (external), raise front power lift; S022 - Switch (external), lower front power lift

The system detects an implausible signal, such as both the raise and lower buttons being pressed simultaneously, or a button being continuously depressed (stuck closed). As a safety consequence, the system forces the front power lift hydraulic valve into neutral, disabling the external operation of the front hitch.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• 300 Vario (COM III)
• 400 Vario (COM III) (e.g., 411, 412, 413, 414, 415)
• 700 Vario (COM III & SCR) (e.g., 712, 714, 716, 718, 720, 722, 724)
• 800 Vario (COM III) (e.g., 818, 820)
• 900 Vario (COM III, SCR, S4) (e.g., 922, 924, 927, 930, 933, 936, 939)

1. 1

   Physical Inspection: Inspect the external front power lift buttons (S021 for raise, S022 for lower) located at the front of the tractor to check if a button is physically jammed by dirt, mud, or ice.

2. 2

   Wiring and Connector Check: Inspect the wiring harness and connectors leading to the switches for corrosion, moisture ingress, or chafing that could cause a short to ground.

3. 3

   Voltage Testing: Using a multimeter, test the digital input voltage at the switch connector with the ignition ON (Not actuated: 3.7 VDC, Actuated: 1.8 VDC). If the voltage reads 1.8 VDC without the button being pressed, the switch is internally shorted/stuck and must be replaced.

1. 1

   Preparation

   Turn off the tractor ignition, remove the key, and disconnect the battery to prevent accidental short circuits.

2. 2

   Access the Switches

   Locate the S021 and S022 external push buttons on the front power lift housing/bracket.

3. 3

   Clean the Area

   Thoroughly clean the area around the switches to prevent dirt from falling into the electrical connectors during removal.

4. 4

   Disconnect Wiring

   Unplug the electrical connector from the back of the faulty switch.

5. 5

   Remove the Switch

   Depress the retaining clips or remove the mounting nut holding the switch in the bracket, and push the switch out of its mounting hole.

6. 6

   Install the New Switch

   Insert the replacement switch into the bracket until it clicks securely into place.

7. 7

   Reconnect

   Plug the electrical connector into the new switch, ensuring the weather seal is seated properly.

8. 8

   Test

   Reconnect the battery, turn on the ignition, and clear the stored fault codes via the tractor terminal. Test the external raise and lower functions to confirm the repair.