Fendt 4.1.82 – Transmission Control Module (A050 - ECU, basic control unit): Plausibility error between the hydrostatic unit speed sensor (drive collector shaft) and the bevel pinion speed sensor

The speed indications from the drive collector shaft rpm Hall sensor (B014) and the driving mode detection bevel pinion sensor (B015) do not match logically. The system detects that the engine/hydrostat speed and the actual travel speed (bevel pinion) are out of sync. The tractor will typically default to Auxiliary operation or Emergency mode.

• 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
• 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 / Farmer 400 (409, 410, 411, 412)
• Fendt 700 Vario / Favorit 700 (711, 712, 714, 716)
• Fendt 800 Vario (815, 817, 818, 822, 824, 826, 828 S4)
• Fendt 900 Vario / Favorit 900 (916, 920, 924, 926, 930, 933, 936, 939 COM III & S4)

1. 1

   Verify if the PTO shaft is currently driving the engine (a trailing or running on condition), as this specific mechanical feedback can sometimes trigger this plausibility error falsely.

2. 2

   Check the transmission control fuses (specifically A013 fuse 13 or fuse 16, depending on your exact model/year) to ensure the sensors are receiving their required 8.5V power supply.

3. 3

   Inspect the B016 travel range detection sensor (potentiometer range change) for signal failures, as a fault here can cause this code.

4. 4

   Inspect the wiring harnesses and connectors for sensors B014 (hydrostatic collecting shaft) and B015 (bevel pinion) for corrosion, breaks, or loose pins.

1. 1

   Power Down & Secure

   Park the tractor on a level surface, apply the handbrake, and turn off the ignition.

2. 2

   Locate the Sensors

   Locate the B014 (collecting shaft) and B015 (bevel pinion) sensors on the Vario transmission housing.

3. 3

   Test Sensor Output

   Using a multimeter or oscilloscope, back-probe the sensor connectors. Verify that the 8.5V reference voltage is present. Check the signal wire while rotating the assembly to ensure the Hall-effect sensors are generating a clean, square-wave speed signal.

4. 4

   Replace Faulty Sensor

   If B014 or B015 fails to produce a logical speed signal (or if B016 fails to read the correct range position), disconnect the wiring harness, unbolt the faulty sensor from the transmission housing, and install the replacement part.

5. 5

   Reassemble & Calibrate

   Reconnect the wiring harnesses. Depending on the exact model and if the B016 range sensor was disturbed, you may need to perform a transmission calibration procedure using the tractor's terminal (Variotronic Ti) or FENDIAS diagnostic software.

6. 6

   Clear Codes

   Clear the fault codes from the Transmission ECU and test drive the tractor to ensure the speeds match and the tractor exits emergency mode.