Fendt 05.1.B1 – Basic Control Unit (A050): S026 - Switch, steering pump flow controller

The system monitors the voltage (u) of the switch. When the engine is OFF, the voltage must be < 1.1 V (typically 0 VDC, indicating the switch is open because there is no oil flow). If the system detects a voltage higher than 1.1 V while the engine is off, it assumes the switch is stuck closed, shorted to voltage, or faulty, and logs this code.

• 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 (COM III)
• Fendt 400 Vario (COM III)
• Fendt 500 Vario (S4 Series)
• Fendt 700 Vario (COM III, S4 Series)
• Fendt 800 Vario (COM III, S4 Series)
• Fendt 900 Vario (COM III, S4 Series)
• Fendt 1000 Vario

1. 1

   Perform Engine OFF Voltage Test: With the engine off, probe the signal wire at the switch. The voltage must be < 1.1 V (ideally 0 VDC).

2. 2

   Perform Engine RUNNING Voltage Test: Start the engine and raise the RPM above 1000. The voltage should jump to > 1.7 V (approx. 6.1 VDC). If it reads 0 VDC while running, the switch is stuck open or flow is genuinely too low.

3. 3

   Inspect Harness & Connector: Inspect separation point X236 (the connector for the S026 switch) for corrosion, backed-out pins, or a short-to-power in the wiring harness.

1. 1

   Locate the Component

   The S026 steering pump flow controller switch is located on the right side of the tractor, at the central valve block / control valves.

2. 2

   Access the Valve Block

   Unbolt and detach the right-side cover/panel to gain access to the central valve block.

3. 3

   Disconnect the Switch

   Locate separation point X236 on the S026 switch and disconnect the wiring harness.

4. 4

   Replace the Switch

   If the wiring tested fine but the switch failed the plausibility check (stuck closed), unthread the faulty S026 switch from the valve block and install the replacement.

5. 5

   Reassembly

   Reconnect the X236 connector, reinstall the right-side panel, and clear the fault codes via the diagnostic interface.

6. 6

   Verification

   Cycle the key and ensure the code does not return when the engine is off.