CLAAS Id78D6h / 78D6h – EXT (A62) - External Function Module: CAN bus communication error: CSM permission message not received or invalid

The CAN "CSM permission" message is not received by the external function module EXT (A62) or it has received an invalid value.

• CLAAS Axion 900 Series (920, 950)
• CLAAS Axion 800 Series (810, 840, 850)
• CLAAS Arion 600 Series (610, 630, 640)
• CLAAS Arion 500 Series (510)
• CLAAS Arion 400 Series (410, 430)

1. 1

   Check the operational status of the Hydraulic Module HYD (A60) and the External Function Module EXT (A62)

2. 2

   Check the CLAAS vehicle CAN bus network for overall health and high numbers of CAN frame errors

3. 3

   Verify the connectors and the continuity of the wiring harnesses linking the HYD (A60) and EXT (A62) components

4. 4

   Check for any short-circuits (to 12V or to ground) or open circuits on the CAN lines

5. 5

   Check the sources of energy for both modules, including fuses, power supply voltage, and ground connections

6. 6

   Check the compatibility of the program versions, settings, and calibration between the modules

1. 1

   Read All Codes

   Identify the nature of each active error code. Analyze the interaction between them, as a primary CAN bus failure (e.g., a short circuit) can generate this specific missing-message code.

2. 2

   Inspect Physical Connections

   Locate the HYD (A60) and EXT (A62) modules. Disconnect their main harnesses and inspect the pins for corrosion, moisture, or pushed-out terminals.

3. 3

   Test the Harness

   Using a multimeter, perform continuity and resistance tests on the CAN High and CAN Low wires between the HYD (A60) module, the EXT (A62) module, and the diagnostic port.

4. 4

   Verify Power and Ground

   Ensure both the HYD and EXT modules are receiving stable 12V power and have clean ground connections. Replace any blown fuses and repair damaged wiring.

5. 5

   Software/Calibration Check

   If the wiring is intact, connect the CLAAS CDS (Computer Diagnostic System) to verify that the software versions of the HYD and EXT modules are compatible and properly calibrated for the CSM function.

6. 6

   Component Replacement

   If a module is found to have an internal hardware failure (e.g., it is receiving power/ground but not outputting CAN signals), replace the faulty module (either HYD A60 or EXT A62).

7. 7

   Clear and Test

   Clear all error codes from the system. Test drive the tractor and engage the CLAAS Sequence Management (CSM) above 20 km/h to ensure the anomaly does not return.