Fendt A.1.92 – A057 - ECU, steering controller (Auto-Guide): Short circuit in the pilot pressure solenoid valve earth (ground)

The system has detected that the electrical supply line to the Y099 solenoid valve is shorted to ground.

• 411 Vario COM III
• 412 Vario COM III
• 413 Vario COM III
• 414 Vario COM III
• 415 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
• 718 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• FENDT 300 Vario (COM III)
• FENDT 400 Vario (COM III)
• FENDT 700 Vario (COM III)
• FENDT 800 Vario (COM III)
• FENDT 900 Vario (COM III)
• FENDT 900 Vario S4 (VarioGuide)

1. 1

   Consult Wiring Diagram Sheet 39 for the Auto-Guide steering valve block circuit

2. 2

   Visually inspect the electrical supply line leading to the Y099 pilot pressure solenoid valve for chafed insulation, pinched wires, or exposed copper shorting to the chassis (earth)

3. 3

   Disconnect the Y099 solenoid and check the connector pins for corrosion, moisture, or damage that could bridge the circuit to ground

4. 4

   Use a multimeter to test the resistance of the Y099 solenoid coil to check if the coil is internally shorted to its own casing

1. 1

   Isolate the Circuit

   Turn off the tractor and ensure the electrical system is powered down.

2. 2

   Access the Valve Block

   Locate the Auto-Guide steering valve block (Component Y087), which houses the Y099 pilot pressure solenoid valve. On some models (like the 900 Vario), this is accessed by removing the right rear wheel and panel.

3. 3

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a short to ground in the harness, repair the damaged wire using appropriate weather-sealed splices, or replace the affected harness section.

4. 4

   Replace Solenoid (If Applicable)

   If the wiring is intact but the solenoid coil is internally shorted, remove the retaining nut/clip on the Y099 solenoid, slide the old coil off the valve stem, and install the replacement.

5. 5

   Clear Fault Codes

   Power the tractor back on and use the terminal display to confirm, call up, and delete the stored A.1.92 fault code from the A057 ECU memory.

6. 6

   Test Operation

   Engage the Auto-Guide system to ensure the pilot pressure valve activates correctly without triggering a new fault.