CLAAS Id78D1h / 78D1h – EXT (A62) - External Function Module: CAN bus communication error: Engine running message not received or invalid

The CAN 'Engine running' message is either not being received by the external function module, or the value being received is invalid.

• Axion 800 series
• Axion 810
• Axion 850
• Axion 900 series
• Axion 920
• Axion 950

1. 1

   Check the TR2 transmission module (A57-2) which processes and broadcasts engine/transmission data

2. 2

   Check the Bus CAN network communication module BDG (A103) which acts as the gateway/relay

3. 3

   Check the external function module EXT (A62) which is logging the fault

1. 1

   Verify Engine Sensors

   Ensure the engine is actually running smoothly and that the engine speed sensors (e.g., on the PTO clutch housing) are functioning, as these feed the 'engine running' status to the system.

2. 2

   Inspect the Wiring Harness

   Check the physical CAN bus wiring and connectors linking the TR2 (A57-2), BDG (A103), and EXT (A62) modules. Look for chafed wires, bent pins, or corrosion that could interrupt the CAN signal.

3. 3

   Test CAN Bus Continuity

   Use a multimeter or oscilloscope to verify CAN-High and CAN-Low voltages and check the terminating resistors on the CLAAS vehicle CAN bus network.

4. 4

   Module Testing

   If the wiring is intact, use a CLAAS diagnostic tool (CDS) to monitor live data. Check if the TR2 module is successfully broadcasting the 'Engine running' message.

5. 5

   Module Replacement/Reprogramming

   If the TR2 is broadcasting the message but the EXT module cannot see it (and the BDG gateway is passing other messages fine), the EXT (A62) module may have an internal fault and require replacement or a software re-flash.