Fendt 05.1.66 – Enhanced Control ECU: Charge Suspension Valve Actuation Fault

Fault code 05.1.66 translates to 'Y012 - Valve, charge suspension: Actuation fault'. This indicates an electrical control fault (such as a short, open circuit, or 12V supply issue) with the Y012 solenoid valve, which is responsible for the front axle suspension charging and hydraulic oil pre-heating. When this fault is triggered, the system defaults to a safety mode, and the suspension moves to the 'Lock' status.

• 309 Vario COM III
• 310 Vario COM III
• 311 Vario COM III
• 312 Vario COM III
• Fendt 300 Vario (COM III)
• Fendt 400 Vario (COM III)
• Fendt 500 Vario (S4)
• Fendt 700 Vario (COM III, S4)
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III, S4)

1. 1

   Locate the Valve: The Y012 valve is typically located at the right entrance step, on top of the central control block (ZSB) in bore 2011. You will need to remove the footplate and metal cover to access it.

2. 2

   Electrical Testing: Check the wiring harness and the electrical connector at separation point X323 (the designated connection for Y012). Look for corrosion, broken wires, or a poor ground.

3. 3

   Actuation Test: Verify if the valve is receiving a 12V signal from the Enhanced Control ECU when the suspension is commanded to charge.

1. 1

2. 2

   Relieve hydraulic pressure

   DANGER: The front axle suspension pressure lines between the central control block (ZSB) and the suspension cylinder, as well as the encased ASP and ZSP pressure accumulators, remain under high pressure (up to 200 bar) even when the engine is switched off and the suspension is lowered/locked. You MUST release this pressure manually before opening the hydraulic system. The electronic "Lock suspension/lower suspension" command has no effect when the system is faulted. You must manually screw in the knurled-head screws on the Y013 (lower suspension) and Y014 (raise suspension) solenoid valves.

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5. 5

   Relieve Y012

   Relieve the rebound accumulator via the Y012 valve. As the oil temperature rises, the emptying accumulator will make a flowing sound (this may be barely audible in winter).

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8. 8

   Access the valve block

   Remove the right entrance footplate and the metal cover panel to expose the central control block.

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10. 10

11. 11

    Disconnect electrics

    Disconnect the wiring harness at separation point X323.

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13. 13

    Remove the valve

    Carefully unscrew and remove the faulty Y012 solenoid valve from bore 2011.

14. 14

    Install the new valve

    Lubricate the O-rings on the new genuine Fendt valve and install it into the control block.

15. 15

    Reassembly

    Reconnect the X323 electrical connector, back out the manual knurled-head screws on the valves to restore normal operation, and reinstall the metal cover and footplate.

16. 16

    Test

    Start the tractor, clear the fault codes, and test the front axle suspension to ensure it charges and levels correctly.