CLAAS Id768Fh / 768Fh (516) – TR3 (A57-3) Transmission Control Module: Open circuit of automatic hand brake sensor disengaged

The system has detected an open circuit in the wiring or the sensor responsible for confirming that the automatic hand brake is disengaged. As a safety precaution, the automatic hand brake becomes inactive and cannot be engaged or disengaged electronically.

• Arion 640-510
• Arion 430-410
• Arion 420
• Axion 850-810
• Axion 950-920

1. 1

   Check for a possible open circuit in the wiring harness of the automatic hand brake sensor (Component ID: Z158).

2. 2

   Check the condition and operation of the sensor (Z158) itself.

3. 3

   Check the 'Auto 5' / TR3 module using CLAAS diagnostic tool n° 60 05 033 249.

1. 1

   Manual Override

   Because the electronic control is inactive, first use the mechanical release screw to manually disengage the automatic hand brake so the tractor can be moved into a workshop.

2. 2

   Harness Inspection

   Locate the automatic hand brake sensor (Z158). Inspect the wiring harness leading to the sensor for broken wires, chafing, or disconnected/corroded pins that would cause an open circuit. Repair any damaged wiring.

3. 3

   Sensor Testing

   Test the Z158 sensor for continuity. If the sensor is internally broken (open circuit) or fails to read the mechanical position of the brake, replace the sensor.

4. 4

   Module Diagnostics

   If the wiring and sensor are both functioning correctly, the fault likely lies within the transmission control module. Connect CLAAS diagnostic tool n° 60 05 033 249 to test the 'Auto 5' (TR3) module.

5. 5

   Module Replacement

   If the diagnostic tool confirms the module is failing to process the sensor's signal, replace the TR3 (A57-3) module.