Fendt A.1.72 – A057 - ECU, Steering Controller (Auto-Guide) or A050 - Basic Control Unit ECU (EXT) - VarioGuide: Y099 - Solenoid valve, pilot pressure (Autoguide)

A break in the electrical supply line (open circuit) to the pilot pressure solenoid valve.

• 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
• Fendt 400 Vario
• Fendt 700 Vario
• Fendt 800 Vario
• Fendt 900 Vario

1. 1

   Check the electrical supply line to the Y099 pilot pressure solenoid valve for a break, chafing, or loose connections (refer to Wiring Diagram Sheet 39)

2. 2

   Use a multimeter to check for continuity between the Steering Controller ECU and the Y099 valve connector

3. 3

   Use the Auto-Guide COM III diagnostic tool box and Y099 adapter cable to safely test the circuit without damaging harness pins

1. 1

   Access the Valve

   Locate the Y099 pilot pressure switch-off solenoid valve on the steering valve block (often located on the right side of the transmission, requiring the removal of the right rear wheel and panel for access on some models).

2. 2

   Inspect and Repair Wiring

   If the diagnostic checks reveal a broken wire or damaged connector pin on the harness side, repair the wiring break or replace the damaged connector terminal.

3. 3

   Test the Solenoid

   If the wiring harness is intact and has good continuity back to the ECU, test the Y099 solenoid valve itself for an internal open circuit (infinite resistance).

4. 4

   Replace the Valve

   If the solenoid coil is internally broken, remove the retaining nut, slide off the old Y099 solenoid coil, and install the replacement.

5. 5

   Calibrate

   After repairing the wiring or replacing the valve, clear the fault codes from the system log. You may need to restart and successfully complete the steering valve calibration process.