Fendt 05.1.9B – A050 - ECU, Basic Control Unit: S025 - Switch, LS pump pressure monitor

This fault code indicates a plausibility error or a direct failure of the Load Sensing (LS) pump pressure monitoring switch (S025). If the signal is interrupted while the engine is running, or if the switch fails to open/close at the correct pressure thresholds, this code is triggered. As a safety measure, the hydraulic spool valves are locked.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt 300 Vario
• Fendt 400 Vario
• Fendt 500 Vario (including S4 series)
• Fendt 700 Vario (COM III, SCR, S4)
• Fendt 800 Vario (COM III, SCR, S4)
• Fendt 900 Vario (COM III, SCR, S4)
• Fendt 1000 Vario

1. 1

   Perform Engine OFF Test: With the ignition ON but the engine OFF, check the voltage at the S025 switch. The switch must be closed, and the signal should read approximately 1.7 VDC.

2. 2

   Perform Engine RUNNING Test: Run the engine above 1000 rpm. If the LS pump is operating correctly (minimum 8 bar), the signal should read between 3.7 VDC and 6.1 VDC. If the pressure is below 8 bar, the signal will drop to 1.8 VDC.

3. 3

   Inspect the wiring harness and the X235 separation point (connector) for the S025 switch. Look for an open circuit, short to ground, or damaged pins between the switch and the A050 ECU (specifically checking Earth pin 46 and the signal wire).

1. 1

   Locate the S025 Switch

   On 500/700/800/900 Vario S4 models: The switch is located on the right side of the tractor, at the top of the central control valve block. You will need to detach the protective cover to access it. On 400 Vario models: It is located at the right entry; remove the hatch cover at the top of the steering column to access the central block.

2. 2

   Depressurize the System

   Ensure the tractor is turned off, the implement is lowered, and residual hydraulic pressure is relieved before loosening any hydraulic fittings.

3. 3

   Disconnect the Switch

   Unplug the X235 electrical connector from the S025 pressure switch.

4. 4

   Remove the Faulty Switch

   Using a wrench, carefully unscrew the S025 pressure switch from the hydraulic block. Have a rag ready to catch minor oil drips.

5. 5

   Install the New Switch

   Thread the new OEM pressure switch into the port and tighten to the manufacturer's specified torque.

6. 6

   Reconnect and Reassemble

   Plug the X235 electrical connector back in and reinstall any covers or hatch panels.

7. 7

   Clear Codes and Test

   Turn on the ignition, clear the 05.1.9B fault code via the terminal, and start the tractor. Rev the engine above 1000 rpm and operate the hydraulic spool valves to ensure the code does not return and the valves are no longer locked.