Fendt 18.2.70 – A050 - ECU, basic control unit: Warning message when ISO is inactive

This fault indicates a communication or activation issue with the Auto-Guide automated steering system. The ISOBUS (ISO) communication to the Y087 steering valve block has dropped, timed out, or is inactive, preventing the tractor's automated steering from functioning.

• 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 700 Vario (COM III, SCR)
• Fendt 800 Vario (COM III, S4)
• Fendt 900 Vario (COM III, SCR, S4)

1. 1

   Check the CAN bus wiring and ISOBUS connectors leading to the Y087 steering valve block for corrosion, moisture, or backed-out pins

2. 2

   Verify the power supply voltage to the Y087 valve (spikes above 32V or drops below 10V can trigger related faults)

3. 3

   Ensure there is no mechanical binding on the steering actuator and that the position sensor wiring is intact

4. 4

   Check if the steering valve has lost its calibration data

1. 1

   Inspect Wiring

   Locate the Y087 steering valve block, disconnect the electrical harness, and clean the contacts with electronic cleaner.

2. 2

   Test Harness

   Use a multimeter to verify continuity on the CAN-High and CAN-Low lines between the Y087 valve connector and the A050 Basic Control Unit / ISOBUS diagnostic port. Repair any broken wires.

3. 3

   Replace Valve

   If the wiring, voltage, and CAN signals are all verified as good but the valve still fails to communicate (internal module failure), replace the Y087 steering valve block.

4. 4

   Recalibrate

   Clear the fault codes using the SERDIA / FENDIAS diagnostic software. If the valve was replaced, perform the steering valve calibration procedure (Calibration code '2403' via the tractor terminal).