Fendt 4.1.67 – Transmission Control Unit (TCU): K051 Relay Contacts Stuck Closed

The relay test was unsuccessful because the K051 relay contacts (Pins 3 and 5) are physically stuck or welded closed, which disables the active parking/hold function.

• 409 Vario
• 410 Vario
• 411 Vario
• 412 Vario
• 711 Vario
• 712 Vario
• 714 Vario
• 715 Vario
• 716 Vario
• 717 Vario
• 718 Vario
• 916 Vario
• 920 Vario
• 924 Vario
• 926 Vario
• 930 Vario
• Farmer 400
• Favorit 700 and Favorit 900
• Fendt 300 Vario (COM III)
• Fendt 400 Vario (COM III) (e.g., 411, 412, 413, 414, 415)
• Fendt 700 Vario (COM III) (e.g., 712, 724)
• Fendt 800 Vario (COM III) (e.g., 820)
• Fendt 900 Vario (COM III) (e.g., 916, 920, 924, 926, 930)

1. 1

   Locate the K051 relay at the right rear in the cab, behind the cover panel.

2. 2

   Remove the K051 relay and use a multimeter to test for continuity between pins 3 and 5. Continuity while unpowered confirms the internal contacts are stuck closed.

3. 3

   Inspect the wiring and signal lines associated with the 'Engine brake and active parking function' circuit for any shorts that may have caused the relay to overload and weld shut.

4. 4

   Verify that the active hold function solenoid valve (Y053) is functioning properly and not shorted, as it operates on the same circuit.

1. 1

   Secure the tractor

   Turn off the tractor and ensure it is safely secured (manually engage the parking brake or chock the wheels since the active hold function is disabled).

2. 2

   Access relay panel

   Access the relay panel located at the right rear of the cab by removing the cover.

3. 3

   Remove faulty relay

   Identify and remove the faulty K051 relay.

4. 4

   Install new relay

   Install a new, equivalent 12V / 30A / 5-pin relay into the K051 slot.

5. 5

   Clear fault codes

   Turn the tractor's ignition on and clear the stored fault codes using the tractor's terminal (typically by pressing and holding the confirmation key, then pressing the clear key until the display resets).

6. 6

   Test function

   Test the active parking/hold function by engaging it to ensure the tractor holds its position and the fault code does not return.