Fendt 4.1.21 – Transmission Control Unit: S045 Reverse operation sensor signal fault

The control unit is receiving an implausible signal, no signal, or an out-of-range voltage from the reverse operation sensor. As a result, reverse mode operation and accelerator pedal mode are no longer possible.

• 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
• Favorit 900
• Fendt 300 Vario
• 400 Vario
• 700 Vario
• 800 Vario
• 900 Vario

1. 1

   Locate the S045 reverse operation sensor/switch and inspect the sensor housing for physical damage.

2. 2

   Inspect the wiring harness leading from the S045 sensor to the Transmission Control Unit for chafed wires, breaks, or corrosion.

3. 3

   Disconnect the sensor and check the pins for moisture, bent pins, or corrosion.

4. 4

   Using a multimeter, verify that the sensor is receiving the correct reference voltage and ground. Test the switch's output signal while manually toggling the reverse operating controls to see if the signal changes state.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent short circuits.

2. 2

   Access the Sensor

   Locate the S045 reverse operation sensor (typically located near the reverse drive control linkage or joystick assembly, depending on the specific Vario cab configuration).

3. 3

   Disconnect

   Unplug the electrical connector from the S045 sensor.

4. 4

   Remove

   Unbolt or unthread the defective S045 sensor from its mounting bracket.

5. 5

   Install

   Mount the new reverse operation sensor and secure it.

6. 6

   Reconnect

   Plug in the electrical connector, ensuring it clicks into place and is free of debris.

7. 7

   Test

   Reconnect the battery, power on the tractor, and use the FENDIAS diagnostic tool (or onboard terminal) to clear the 4.1.21 fault code. Test the reverse mode and accelerator pedal operation to confirm the fix.