Fendt 1.1.03 – A050 (EST/EXT) Basic Control Unit / A051 / A127 (EDC/EMR) Engine Control Unit: Plausibility error with the B055 - Sensor, foot throttle

The signal sent to the basic control unit does not match the signal sent to the engine control unit. The system detects that the values between the two redundant circuits (Pin 3 to Pin 6) do not correspond, or the signal is too high, too low, or missing for longer than 2000 ms. The tractor will enter a restricted operating mode (emergency mode) and the Tractor Management System (TMS) will be switched off.

• 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 I, COM II, COM III)
• Fendt 400 Vario (COM I, COM II, COM III)
• Fendt 700 Vario (COM I, COM II, COM III, SCR)
• Fendt 800 Vario (COM I, COM II, COM III, S4)
• Fendt 900 Vario (COM I, COM II, COM III, S4)
• Fendt Favorit 900

1. 1

   Visual Inspection: Check the foot throttle pedal assembly for physical damage, packed dirt, or debris that might prevent the pedal from returning to its resting position or achieving full travel.

2. 2

   Wiring & Harness Check: Inspect the wiring harness between the B055 sensor, the A050 Basic Control Unit, and the Engine Control Unit. Look for chafing, cable breaks, or short circuits.

3. 3

   Voltage & Ground Verification: Verify the 5.0 VDC supply (typically on Pins 2 and 5) and check the grounds (Pins 1 and 4).

4. 4

   Signal Testing: Monitor the signal outputs (Pins 3 and 6) while slowly depressing the pedal. The voltage should change smoothly without any dropouts or spikes.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent electrical spikes during repair.

2. 2

   Remove the Sensor

   Access the foot throttle pedal assembly in the cab. Disconnect the 6-pin electrical connector from the B055 sensor. Unbolt and remove the faulty rotary position sensor from the pedal shaft.

3. 3

   Install the New Sensor

   Mount the replacement B055 sensor to the pedal assembly, ensuring the shaft aligns correctly with the potentiometer drive. Secure the mounting bolts and reconnect the 6-pin harness.

4. 4

   Calibration / EOL Programming

   Using the FENDIAS diagnostic tool, navigate to TRANSMISSION, AUTOMATIC MAXIMUM OUTPUT CONTROL and run Calibration code '4005'. End-of-Line (EOL) reprogramming may be necessary if the A050 basic control unit threw an internal EEPROM error due to the fault.

5. 5

   Clear Codes

   Clear the stored EDC/Transmission faults (FC: 1.1.03) using FENDIAS or SERDIA.

6. 6

   Test Drive

   Restart the tractor and verify that the TMS system is functional and the foot throttle responds smoothly without triggering emergency mode.