CLAAS 75D9h – TR1 (A57-1): Speed Sensor Inconsistency

The transmission control module (TR1) detects an inconsistency between the theoretical speed (calculated based on the selected gear range) and the actual speed measured by one or more speed sensors. This conflict indicates that the transmission's operational state does not match the commanded state, which is typically caused by faulty range engaged contacts, wiring issues, or a mechanical fault within the range module.

• Axion 850-810
• Axion 800 series
• Arion 640-510
• Axion 810 Stage V

1. 1

   Review active fault codes for related issues (e.g., 75CEh for theoretical speed sensor B227 or 75CCh for reverser exit speed sensor B229)

2. 2

   Check the theoretical ground speed sensor (B227) for communication errors

3. 3

   Inspect sensors for accumulation of contaminants like dirt, oil, or metal debris that can interfere with accurate readings

4. 4

   Inspect connectors and harness continuity for the reverser output and theoretical speed sensors, checking for short or open circuits

5. 5

   Verify power supply, including fuses, supply voltage, and ground connections to the sensors

6. 6

   Check the internal resistance of the sensors (note that resistance can vary significantly with temperature)

7. 7

   Check operating conditions of the components for mechanical seizing

1. 1

   Access the sensors

   Locate the reverser output and theoretical speed sensors. Depending on the model, these may be externally mounted on the transmission housing, require valve body removal, or require splitting the tractor.

2. 2

   Adjust sensor air gap

   If applicable to the specific sensor (e.g., engine speed sensor B228-2 on Axion 850-810), adjust the sensor to set a precise air gap (e.g., 1 mm) between the sensor and the target plate.

3. 3

   Replace faulty sensor

   If a sensor is faulty, replace it. Ensure correct installation to prevent electronic noise or incorrect clearance. Do not over-torque. Note any specific dimensions from the old sensor (e.g., 22.5 mm) and apply to the new one.

4. 4

   Clear fault codes

   After completing repairs, clear all fault codes from the transmission control module.

5. 5

   Test operation

   Operate the tractor to verify that the transmission functions correctly and the fault code does not return.