CLAAS Id7687h / 7687h (508) – TR3 (A57-3): Steering pressure below 9 bar during engine speed drop

The Powertrain CAN bus has detected a major drop in engine speed accompanied by a steering pressure reading that has fallen below 9 bar for a duration of 4 seconds, causing the PTO to be automatically forced off.

• CLAAS Axion 800 Series
• CLAAS Axion 810
• CLAAS Axion 850
• CLAAS Axion 900 Series
• CLAAS Axion 920
• CLAAS Axion 950

1. 1

   Check the actual steering pressure mechanically/hydraulically to verify it can maintain above 9 bar

2. 2

   Check the steering pressure sensor (Component Z154) for accurate readings

3. 3

   Inspect the Powertrain CAN bus network wiring harnesses and connectors for continuity, shorts, or open circuits

4. 4

   Test the 'Auto 5' module to ensure it is processing CAN bus information correctly

1. 1

   Hydraulic Test

   Hook up a mechanical pressure gauge to the steering hydraulic circuit. Start the engine and monitor the pressure. If the physical pressure actually drops below 9 bar during a drop in engine speed, you have a hydraulic issue (e.g., a failing steering pump or a hydraulic leak) rather than an electrical fault.

2. 2

   Sensor Verification

   If the physical steering pressure is healthy (above 9 bar), inspect the wiring harness connecting to the Z154 steering pressure sensor. Look for corrosion, damaged pins, or wire chafing.

3. 3

   Sensor Replacement

   If the wiring is intact but the CAN bus is still receiving a sub-9 bar reading, replace the Z154 steering pressure sensor.

4. 4

   Module Replacement

   If the sensor, hydraulic pressure, and CAN bus network all test perfectly, the fault lies in the 'Auto 5' electronic control module. Test and change this module if required.