Fendt 05.1.99 – A050 - ECU, basic control unit or A002 - ECU, enhanced control unit: S026 - Switch, steering pump flow controller

The flow monitor is reporting a steering pump (or auxiliary/constant displacement pump) failure. The system monitors the hydraulic oil flow volume from the steering pump once the engine exceeds 1000 RPM. If the voltage signal from the S026 switch does not exceed 1.1 V (or 1.7 V), the system registers that the minimum flow volume has not been reached.

• 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 Series
• 400 Vario Series (411, 412)
• 700 Vario Series (711, 712, 714, 716)
• 800 Vario Series (815, 817, 818)
• 900 Vario Series (916, 920, 922, 924, 926, 927, 930, 933, 936)

1. 1

   Ensure the engine is at idle (800 rpm) and the hydraulic oil temperature is between 40-50°C. Do not actuate the steering during the test.

2. 2

   Increase engine speed to >1000 rpm. Measure the voltage at the S026 switch. The voltage must be > 1.1 V (or > 1.7 V on some COM III models).

3. 3

   Turn the engine off. The voltage must drop to < 1.1 V.

4. 4

   Check the signal at separation point X236. If flow volume is OK, the switch should be OPEN, reading approximately 6.1 VDC (or 5.1 VDC). If flow volume is too low, the switch should be CLOSED, reading 0 VDC.

5. 5

   Inspect the signal line for a short-circuit to earth, which will cause a constant 0 V reading.

1. 1

   Park the tractor on a level surface, engage the handbrake, and turn off the engine.

   Ensure the tractor is safely parked before beginning repairs.

2. 2

   Release any residual hydraulic pressure.

   Use the trailer brake button if applicable to release pressure.

3. 3

   Locate the S026 switch.

   It is positioned on the right side of the tractor, at the central valve block / control valves.

4. 4

   Remove the right-side protective panel/cover.

   This provides access to the central valve block.

5. 5

   Disconnect the electrical connector at separation point X236.

   Disconnect the wiring from the faulty switch.

6. 6

   Unscrew the faulty S026 steering pump flow controller switch from the hydraulic block.

   Have a rag ready to catch minor oil seepage.

7. 7

   Install the new switch and tighten it to the manufacturer's specification.

   Ensure the new switch is securely installed.

8. 8

   Reconnect the X236 electrical connector.

   Restore the electrical connection to the new switch.

9. 9

   Reinstall the right-side cover.

   Replace the protective panel over the central valve block.

10. 10

    Start the tractor, warm the hydraulic oil to 40-50°C, and run the engine above 1000 rpm to verify the fault code clears.

    A key reset/restart is required to clear this specific fault code from the active memory.