Fendt 04.1.06 – A050 - Basic Control Unit ECU / A051 - EDC Engine Control Unit (EDC 7): B055 - Sensor, foot throttle (Signal fault / Sensor faulty)

The B055 foot throttle sensor signal is too high, too low, or missing for longer than 2000 ms. It can also be caused by a failure in the 8.5V power supply to the sensor. The tractor will enter an emergency operating mode, the Tractor Management System (TMS) will be switched off until the next cold start, and engine speed can only be controlled via the hand throttle.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• 200 V/F/P Vario series
• 300 Vario (COM III)
• 400 Vario (COM III)
• 700 Vario (COM III, SCR, S4)
• 800 Vario (COM III, SCR, S4)
• 900 Vario (COM III, SCR, S4)

1. 1

   Check the Power Supply: Verify the 8.5V supply to the sensor from the A013 module. Specifically, check Fuse 19, which protects this circuit.

2. 2

   Inspect Wiring and Connectors: Check the wiring harness between the B055 sensor and the A050/A051 ECUs for cable breaks, chafing, or short circuits.

3. 3

   Test Sensor Output: Using a multimeter and a Y-harness breakout cable (Fendt tool X899.980.246.208 or X899.980.259.102), measure the voltage signals from the sensor pins while depressing the pedal to see if the potentiometers have dead spots.

4. 4

   Check Mechanical Linkage: Ensure the pedal mechanism is not physically jammed, preventing full rotation of the sensor shaft.

1. 1

   Power Down

   Turn off the tractor ignition and disconnect the battery ground to prevent electrical spikes.

2. 2

   Access the Sensor

   Locate the B055 rotary position sensor mounted on the side of the foot throttle pedal assembly in the cab.

3. 3

   Remove the Faulty Sensor

   Disconnect the multi-pin electrical connector. Remove the mounting screws securing the sensor to the pedal shaft and slide the sensor off.

4. 4

   Install the New Sensor

   Slide the new sensor onto the pedal shaft, ensuring the internal tangs align correctly with the shaft's rotation path. Secure the mounting screws and reconnect the wiring harness.

5. 5

   Calibrate the Sensor

   A newly installed B055 sensor must be calibrated to the ECUs so they can learn the new idle and full-throttle voltage limits. This is typically done using the FENDIAS diagnostic software or the tractor's onboard terminal using Calibration Code 4005 (Transmission Load Limit Control) or Calibration Code 4010 (Hand throttle and throttle pedal speed range).

6. 6

   Clear Codes

   Use SERDIA or FENDIAS to clear the stored 04.1.06 fault code from the EDC and transmission control modules.

7. 7

   Test Operation

   Restart the tractor and verify that TMS can be engaged and that the foot pedal smoothly controls engine RPM without triggering emergency mode.