Fendt A.1.50 – Transmission Control Unit / Basic Control Unit (A050): S053 - Switch, driver seat

The system detects a signal fault from the seat switch, specifically noting that the seat is not "loaded" (unoccupied) when steering or travel is activated.

• 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)
• Fendt 700 Vario (COM III)
• Fendt 800 Vario (COM III and S4)
• Fendt 900 Vario (COM III and S4)

1. 1

   Ensure the driver is firmly sitting on the seat for more than 3 seconds, as the system requires a continuous load signal

2. 2

   Test the S053 seat switch resistance and voltage with a multimeter (Unoccupied: ~510 ohms / 3.7-6.1 VDC; Occupied: ~121 ohms / 1.8 VDC)

3. 3

   Inspect the wiring harness under the seat for pinched wires, disconnected plugs, or shorts to the sensor system earth

4. 4

   Use the FENDIAS diagnostic program or the tractor's terminal (A008) to monitor the live status of the S053 switch

1. 1

   Power Down

   Turn off the tractor and remove the key to ensure the transmission and basic control units are powered down.

2. 2

   Access the Switch

   Locate the S053 driver seat switch, which is typically mounted within the bottom cushion assembly or suspension base of the driver's seat.

3. 3

   Disconnect

   Unplug the electrical connector leading to the seat switch.

4. 4

   Remove and Replace

   If the switch failed the multimeter diagnostic checks (e.g., showing an open circuit when loaded), unclip or unbolt the faulty switch from the seat frame and install the new switch.

5. 5

   Reconnect

   Plug the electrical connector back into the new switch. Ensure the wiring is routed safely away from the seat's suspension scissor mechanism to prevent future pinching.

6. 6

   Test

   Turn the tractor on, sit in the seat, and attempt to select a direction of travel in accelerator pedal mode to verify the system recognizes the operator.

7. 7

   Clear Codes

   Call up the stored fault codes on the tractor terminal and delete the A.1.50 fault message from the memory.