CLAAS Id7688h / 7688h (509) – TR3 (A57-3): Engine speed information on the Powertrain CAN bus (from the TR2) incoherent

The transmission control system is receiving conflicting, missing, or erratic engine speed data over the Powertrain CAN bus from the TR2 module. Because the system cannot accurately verify the engine speed against the PTO speed, the system response is a safety override: The PTO is automatically turned off.

• Axion 800
• Axion 810
• Axion 820
• Axion 830
• Axion 840
• Axion 850
• Arion 410
• Arion 420
• Arion 430
• Arion 510
• Arion 520
• Arion 530
• Arion 540
• Arion 610
• Arion 620
• Arion 630
• Arion 640

1. 1

   Verify the rear PTO speed sensor (Component B142) is reading correctly and not damaged.

2. 2

   Check the rear PTO clutch for mechanical slippage or failure.

3. 3

   Inspect the engine speed sensors, specifically the engine speed sensor on the PTO clutch housing (Component B228-1) and the engine speed sensor on the gearbox entry shaft (Component B228-2).

4. 4

   Inspect the Powertrain CAN bus network for wiring faults, shorts, or communication drops between the TR2 and TR3 modules.

5. 5

   Test the Auto 5 module using CLAAS diagnostic tool n° 60 05 033 249.

1. 1

   Visual & Harness Inspection

   Check the connectors and the continuity of the wiring harnesses linking the PTO speed sensor (B142), the engine speed sensors (B228-1 / B228-2), and the TR2/TR3 modules.

2. 2

   Electrical Testing

   Check for any short-circuits to ground or open circuits in the sensor wiring. Check the component's resistance against factory specifications.

3. 3

   Power Supply Check

   Verify the sources of energy (fuses, supply voltage, and ground) to the transmission modules.

4. 4

   Mechanical Inspection

   Check the PTO clutch operating conditions (pressure, temperature, mechanical seizing, or excessive load causing slippage).

5. 5

   Software/Calibration

   Check the compatibility of the program versions, settings, and calibration of the Auto 5 module using the CLAAS diagnostic tool.

6. 6

   Component Replacement

   If a sensor fails the resistance/continuity test, or if the Auto 5 module fails the diagnostic tool test, replace the faulty component and clear the codes.