Fendt 05.1.98 – Hydraulics ECU: S025 - Switch, LS pump pressure monitor

Triggered when the Load Sensing (LS) hydraulic pump pressure (PR) drops below 8 bar (116 PSI) while the engine speed exceeds 1000 rpm. As a safety measure, the tractor's hydraulic valves and EPC are immediately locked to prevent damage.

• 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 (311, 312)
• 400 Vario (411, 412, 415)
• 500 Vario
• 700 Vario (711, 712, 714, 716, 724)
• 800 Vario (815, 817, 818, 820)
• 900 Vario (916, 920, 922, 924, 926, 927, 930, 933, 936, 939)

1. 1

   Verify engine speed: Ensure you are testing the tractor with the engine running above 1000 rpm, as the digital input for this monitor is ignored at idle.

2. 2

   Check voltage at switch (S025): Locate separation point X235 (Earth pin 46). If pressure is > 8 bar, voltage should read 3.7–6.1 VDC. If pressure is < 8 bar, voltage drops to approximately 1.8 VDC (or 0–2.4 VDC depending on generation).

3. 3

   Perform a manual pressure test: Connect a manual hydraulic pressure gauge to the LS pump test port (PR) and run the engine above 1000 rpm. If pressure is > 8 bar but the fault is active, the switch or wiring is faulty. If pressure is < 8 bar, the LS pump is failing or there is an internal leak.

1. 1

   Locate the Component

   The S025 switch is typically located on the right side of the tractor, at the top of the central control valve block. Unscrew and detach the right entry cover panels to access it.

2. 2

   Inspect Wiring

   Check the wiring harness leading to the S025 switch (specifically connector X235) for chafing, corrosion, or a short circuit to earth. Repair any damaged wires.

3. 3

   Replace the Switch

   If mechanical pressure is good: Clean the area around the central control block to prevent dirt from entering the hydraulic system. Disconnect the electrical harness from the S025 switch, unthread the faulty pressure switch from the valve block, thread in the new OEM pressure switch (do not overtighten), and reconnect the wiring harness.

4. 4

   Hydraulic Pump Repair

   If mechanical pressure is bad (manual gauge confirmed low pressure): The LS pump must be removed and rebuilt or replaced according to the specific mechanical procedures for your Vario model.

5. 5

   Clear Codes and Test

   Clear the stored 05.1.98 fault code from the tractor's memory. Start the tractor, bring the RPMs above 1000, and verify that the hydraulic valves unlock and operate normally.