CLAAS Id768Ah / 768Ah (511) – TR3 (A57-3) Transmission Module: Loss of information from the rear PTO sensor.

This code indicates that the control module is no longer receiving a valid speed signal from the rear Power Take-Off (PTO) speed sensor. As a result of this underlying condition, the PTO will continue running in poor conditions and will be clutched with a default progressivity rather than its normal modulated engagement.

• Axion 810
• Axion 850
• Arion 410
• Arion 430
• Arion 510
• Arion 530
• Arion 550
• Arion 620
• Arion 640
• Ares
• Celtis

1. 1

   Check the rear PTO speed sensor (B142): Inspect for physical damage and verify the component's resistance.

2. 2

   Check sensor adjustment: Ensure the B142 sensor is properly gapped and adjusted in the housing.

3. 3

   Check the wiring harness: Inspect the connectors and test the continuity of the harnesses linking the sensor to the TR3 module. Check for any short-circuits or open circuits.

4. 4

   Check energy sources: Verify the fuses, power supply (12V), and ground connections to the sensor circuit.

5. 5

   Check the rear PTO clutch: Inspect for mechanical seizing, pressure issues, or temperature abnormalities.

6. 6

   Check the 'Auto 5' module: If the sensor and wiring are intact, the 'Auto 5' module must be tested using CLAAS diagnostic tool n° 60 05 033 249.

1. 1

   Safety First

   Turn off the tractor, remove the key, and engage the parking brake.

2. 2

   Locate the Sensor

   Locate the rear PTO speed sensor (Component B142) on the rear PTO clutch housing.

3. 3

   Inspect Wiring & Connectors

   Disconnect the 3-pin electrical connector from the sensor. Inspect the pins for corrosion, moisture, or damage. Clean with contact cleaner if necessary.

4. 4

   Test the Circuit

   Using a multimeter, verify continuity between the sensor connector and the TR3 (A57-3) transmission module harness. Ensure there are no shorts to ground or open wires.

5. 5

   Check Sensor Seating

   Verify that the sensor is securely mounted and correctly adjusted to the proper depth/gap.

6. 6

   Replace the Sensor

   If the wiring is good but the sensor fails resistance testing or is physically damaged, remove the retaining bolt, extract the old sensor, lubricate the O-ring on the new sensor, and install it.

7. 7

   Inspect the PTO Clutch

   If the sensor is functioning properly, inspect the rear PTO clutch assembly for mechanical faults.

8. 8

   Module Testing

   If the fault persists after sensor replacement and clutch inspection, use CLAAS tool n° 60 05 033 249 to diagnose the "Auto 5" module. Replace the module if it is found to be faulty.

9. 9

   Clear Codes

   Reconnect all components, power on the machine, clear the fault codes, and test the PTO engagement to ensure the default progressivity issue is resolved.