Fendt 4.1.2A – Transmission Control Unit (TCU): B015 Bevel Pinion Direction Hall Sensor Signal Fault

The control unit is not receiving a plausible signal from the B015 Hall-effect sensor, which measures the rotational speed and detects the direction of rotation of the transmission's bevel pinion. The tractor will typically default to 'Only 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
• Farmer 400 Vario Series (409, 410, 411, 412)
• Favorit 700 Vario Series (711, 712, 714, 716)
• Favorit 900 Vario Series (916, 920, 924, 926, 930)
• 300 Vario COM III
• 400 Vario COM III
• 700 Vario COM III
• 800 Vario COM III
• 900 Vario COM III & S4
• 1000 Vario S4 Series

1. 1

   Check the 8.5V power supply to the B015 sensor at the A013 fuse block (inspect Fuse 2 or Fuse 7 depending on the model)

2. 2

   Inspect connectors X1330 (direction detection) and X1331 (speed signal) for corrosion, moisture, or backed-out pins

3. 3

   Inspect the wiring harness between the B015 sensor and the Transmission ECU for chafing or breaks

4. 4

   Perform a plausibility check using a diagnostic tool to verify if the B014 (collecting shaft) and B015 (bevel pinion) sensor speeds match

1. 1

   Preparation

   Park the tractor on a level surface, engage the parking brake, and turn off the engine. Disconnect the battery to prevent electrical shorts during the repair.

2. 2

   Locate the Sensor

   The B015 sensor is located on the Vario transmission housing, reading the bevel pinion gear.

3. 3

   Removal

   Disconnect the electrical connector from the B015 sensor. Remove the retaining bolt securing the sensor to the transmission housing. Carefully pull the sensor straight out of its bore. Have a rag ready, as a small amount of transmission oil may weep from the port.

4. 4

   Installation

   Lubricate the O-ring on the new sensor with clean transmission oil. Insert the new sensor into the bore and secure it with the retaining bolt. Reconnect the electrical connector, ensuring it clicks into place.

5. 5

   Testing

   Reconnect the battery. Turn the ignition on and use the Variotronic terminal (or a diagnostic tool) to clear the stored 4.1.2A fault code. Test drive the tractor to ensure the transmission shifts smoothly and the speed/direction are accurately reported.