CLAAS Id7641h / 7641h (434) – TR2 (A57-2) Transmission Module: During operation Powerboost only in C and D

Engine Speed Sensor 1 of 2 is disconnected or providing a bad measurement. Because the system loses reliable engine speed data, the CLAAS Power Management (Powerboost) restricts itself and is only available in transmission ranges C and D.

• AXION 810
• AXION 820
• AXION 830
• AXION 840
• AXION 850
• ARION 410
• ARION 430
• ARION 510
• ARION 640

1. 1

   Inspect the physical condition and adjustment of the two engine speed sensors: B228-1 (PTO clutch housing) and B228-2 (gearbox entry/primary shaft).

2. 2

   Inspect the wiring harness for Sensor 1 (B228-1) for any disconnections, chafing, or short circuits.

3. 3

   Test the 'Auto 5' module using CLAAS diagnostic tool n° 60 05 033 249 to ensure the module itself hasn't failed.

1. 1

   Locate sensor

   Locate the faulty engine speed sensor on the transmission casing.

2. 2

   Measure dimension

   Before removing the old sensor, measure and note the dimension (a) of the sensor's threaded rod protruding from its carrier. The original factory dimension is typically 22.5 mm.

3. 3

   Remove sensor

   Remove the faulty sensor.

4. 4

   Prepare new sensor

   Prepare the new sensor by smearing the threaded rod slightly with medium-strength threadlocker (Loctite 243).

5. 5

   Fit new sensor

   Fit the new sensor into the carrier, maintaining the exact dimension (22.5 mm) measured from the previous sensor.

6. 6

   Alternative adjustment

   Alternative Adjustment (Tractor Uncoupled): If adjusting from scratch, tighten or loosen the sensor in its carrier to obtain exactly a 1 mm air gap between the sensor tip and the reading plate. Verify this gap using feeler gauges.

7. 7

   Reconnect and test

   Reconnect the sensor harness, clear the fault codes, and test the tractor to ensure Powerboost functions in all ranges.