Fendt A.1.90 – A002 - ECU, Enhanced Control: Short circuit in steering angle sensor earth

Short circuit in steering angle sensor earth (a short to ground on the sensor's ground circuit). Because the system loses the valid steering angle signal, the 4WD and differential lock automatic systems become inoperable.

• 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 (COM III) / Farmer 400
• FENDT 700 Vario (COM III) / Favorit 700
• FENDT 800 Vario (COM III) / Favorit 800
• FENDT 900 Vario (COM III) / Favorit 900
• Fendt Farmer 409
• Fendt Farmer 410
• Fendt Farmer 411
• Fendt Farmer 412
• Fendt Vario 712
• Fendt Vario 714
• Fendt Vario 716
• Fendt 500 series

1. 1

   Inspect the wiring harness leading to the B094 steering angle sensor (located on the front axle) for physical damage, rubbing, or pinched wires

2. 2

   Using a multimeter, check the sensor's earth (ground) wire for a short circuit to ground

3. 3

   Verify that the sensor is receiving the correct reference voltage from the Enhanced Control ECU

4. 4

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

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to protect the Enhanced Control ECU.

2. 2

   Access the Sensor

   Locate the B094 steering angle sensor on the front axle steering cylinder/linkage.

3. 3

   Wiring Repair

   If the diagnostic checks revealed a short in the harness, repair the damaged section of the wiring and re-loom it securely.

4. 4

   Sensor Replacement

   If the wiring is intact and the sensor has failed internally, remove the mounting hardware and extract the old steering angle sensor. Install the new sensor and secure the universal joint/linkage.

5. 5

   Reconnect

   Plug in the electrical connector and reconnect the battery.

6. 6

   Calibration

   Access the tractor's diagnostic/calibration menu and run Calibration Code 2401 (Steering angle sensor calibration). This process teaches the ECU the left lock, right lock, and center positions.

7. 7

   Clear Codes

   Clear the stored A.1.90 fault code from the ECU memory and test drive the tractor to verify that the 4WD/differential lock automatic system is functioning normally.