CLAAS Id781Eh / 781Eh – HYD (A60): Signal of the front lifting position sensor is low or outside the calibration range

When this fault is active, the tractor's system cannot accurately determine the height of the front linkage. As a protective measure, the front lifting operates without position check (open-loop control), meaning automatic depth/height regulation is disabled.

• Axion 800 series
• Axion 900 series

1. 1

   Inspect the front lifting position sensor (Component ID: B139-1) and the hydraulic module HYD (A60)

2. 2

   Check the connectors and the continuity of the wiring harnesses linking the B139-1 sensor to the A60 module

3. 3

   Test the circuit for any short-circuits to ground or open circuits

4. 4

   Check the sources of energy to the sensor, including fuses, 5V supply voltage, and ground

5. 5

   Check the component's internal resistance and physical adjustment/mounting on the front linkage

6. 6

   Verify the compatibility of program versions and check if the sensor simply lost its calibration values

1. 1

   Visual Inspection

   Locate the front lifting position sensor (B139-1) on the front linkage assembly. Inspect the sensor linkage rod, the sensor body, and the wiring pigtail for physical damage.

2. 2

   Wiring Repair

   If the harness is damaged, repair the broken wires or replace the connector.

3. 3

   Sensor Replacement

   If the wiring and power supply (5V and ground) are intact but the sensor output voltage remains out of range (too low), remove the faulty B139-1 sensor and install a replacement.

4. 4

   Recalibration

   Once the voltage is correct, use the CLAAS Diagnostic System (CDS) to perform the 'Front lifting position sensor' calibration routine (setting the LearnFrontHitchPositionMin and LearnFrontHitchPositionMax values) so the HYD module learns the new sensor's physical travel limits.