Fendt A.1.42 – Tractor / General System: Y018 - Auxiliary control valve (Spool Valve 4) supply voltage too low

The supply voltage to the spool valve is too low (Supply voltage < 8 volts). As a safety measure, the valve automatically moves into the neutral position and locks out actuation.

• 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
• Fendt 700 Vario (COM III) / Favorit 700
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III) / Favorit 900 (e.g., 916, 920, 924, 926, 930)

1. 1

   Check the supply voltage directly at the Y018 valve connector (Connector X329) to see if it is dropping below 8 volts

2. 2

   Inspect the wiring harness leading to Valve 4 for chafing, breaks, or severe corrosion that could cause a voltage drop

3. 3

   Verify the fuses supplying the CAN bus and valve control boards (e.g., fuses F040, F041)

4. 4

   Ensure the valve is properly registered on the CAN bus, as failing valve electronics may report low voltage internally even if the harness supplies the correct voltage

1. 1

   Relieve Pressure

   Ensure the tractor is turned off and relieve all hydraulic pressure from the system before working on the valve block.

2. 2

   Access the Valve Block

   Locate the auxiliary control valve block (often located on top of the rear axle housing; access may require removing the right step, right auxiliary tank, or floor panels depending on the model).

3. 3

   Electrical Repair

   If the diagnostic checks revealed a wiring fault, repair the broken wire or replace the corroded X329 connector.

4. 4

   Valve Replacement

   If the harness supplies >12V but the fault persists, the internal electronics of the Y018 valve are defective. Disconnect the hydraulic lines and electrical connector, unbolt Valve 4 from the central control block, and install the replacement valve.

5. 5

   EOL Programming

   Note that auxiliary control valves are programmed for their specific position (Position 4 / Green) in the End-of-Line (EOL) program. A new valve may require calibration or registration via the FENDIAS diagnostic tool to be recognized by the valve bus.