Fendt 9.1.55 – ECU, enhanced control (A002): Spool valve fault – Overvoltage (> 45 volts)

The system detects an abnormally high voltage spike (over 45V) at the Y019 auxiliary control valve. As a safety measure, the valve automatically moves into the neutral position and locks out.

• 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) / Farmer 400 (e.g., 409, 410, 411, 412)
• Fendt 700 Vario (COM III) / Favorit 700 (e.g., 711, 712, 714, 716)
• Fendt 800 Vario (COM III) (e.g., 815, 817, 818)
• Fendt 900 Vario (COM I, II, III) / Favorit 900 (e.g., 916, 920, 924, 926, 930)

1. 1

   System Voltage Check: Test the tractor's charging system and alternator regulator. A failing alternator regulator can send massive voltage spikes through the electrical system.

2. 2

   Wiring Harness Inspection: Inspect the wiring harness leading to the Y019 valve (often located on the right side of the transmission/central control block) for chafed wires that could be shorting to a higher voltage source.

3. 3

   CAN Bus & Power Supply Check: Verify the power supply for the CAN bus on printed circuit board A013. Check fuses F040, F041, and F047 to ensure they are intact and not bypassed with incorrect ratings.

4. 4

   Connector Inspection: Disconnect the Y019 valve (Connector X330) and check for corrosion, water ingress, or damaged pins that could cause electrical shorts.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent further electrical damage.

2. 2

   Resolve Voltage Issues

   If the alternator was found to be overcharging during diagnostics, replace the alternator/voltage regulator before proceeding, or the new valve will be damaged.

3. 3

   Repair Wiring

   Repair any chafed or shorted wires in the harness leading to the Y019 valve.

4. 4

   Replace the Valve

   If the tractor's voltage is normal (12V/24V) and the wiring is intact, the internal circuit board of the Y019 valve has likely failed. Relieve all hydraulic pressure, disconnect connector X330, unbolt the spool valve head/assembly, and install the new auxiliary control valve with new O-rings.

5. 5

   Calibration

   After replacing an electric spool valve, the new valve must be calibrated/taught to the tractor's ECU using the FENDIAS diagnostic software or the tractor's EOL (End of Line) programming terminal.