CLAAS Id78B1h / 78B1h (841) – TR2 (A57-2) Transmission Module: The gearbox is disconnected during a sequence CSM.

The tractor's gearbox has been disconnected or interrupted while a CLAAS Sequence Management (CSM) headland sequence was actively running. The system response is that the sequence is immediately stopped.

• Axion 810
• Axion 820
• Axion 830
• Axion 840
• Axion 850
• Axion 920
• Axion 930
• Axion 940
• Axion 950
• Arion 410
• Arion 430
• Arion 510
• Arion 520
• Arion 530
• Arion 540
• Arion 550
• Arion 610
• Arion 620
• Arion 630
• Arion 640
• Arion 650

1. 1

   Verify if the operator manually interrupted the sequence (e.g., by pressing the clutch pedal or manually shifting), which naturally disconnects the gearbox

2. 2

   Check for related communication codes such as Id78B0h (840) or Id78B2h (842), which indicate a communication loss between the TR2 transmission module and the EXT external function module

3. 3

   Inspect the connectors and continuity of the wiring harnesses linking the TR2 (A57-2) module and the EXT (A62) module

4. 4

   Check the Powertrain CAN bus and the CLAAS vehicle CAN bus networks for short-circuits or open circuits

5. 5

   Check the energy sources (fuses, power supply voltage, and ground) to the TR2 module

1. 1

   Relaunch the Sequence

   Wait for the sequence to be relaunched. Clear the code and attempt to run the CSM sequence again. If it operates normally, the fault was a temporary operational abort.

2. 2

   Inspect the TR2 Module Connectors

   Locate the TR2 (A57-2) module behind the driver's seat. Disconnect the 42-pin connector and inspect for bent pins, corrosion, or moisture. Clean and reseat the connector.

3. 3

   Test CAN Communication

   Perform a continuity test on the CAN bus lines between the TR2 module and the EXT (A62) external function module. Repair any damaged wiring or replace faulty CAN bus resistors.

4. 4

   Module Replacement

   If the wiring is intact and communication lines are verified, but the TR2 module continues to drop communication or fail, the TR2 'Auto 5' module itself may be defective. Replace the module and use the CLAAS Diagnostic System (CDS) to reprogram and calibrate the new unit.