CLAAS Id78D5h / 78D5h – EXT (A62) - External Function Module: CAN bus communication error: Stop contact message not received or invalid

The CAN 'Stop contact' message is either not being received by the external function module, or the value being received is invalid. The communication failure directly involves the MFA (A100) - Armrest Multifunction Module, which is responsible for sending the signal.

• Axion 810
• Axion 850
• Axion 920
• Axion 950
• Arion 510
• Arion 530
• Arion 550
• Arion 620
• Arion 640
• Arion 650

1. 1

   Check the operational status of the MFA (A100) armrest multifunction module and the EXT (A62) external function module.

2. 2

   Inspect the CLAAS vehicle CAN bus network linking these two components.

3. 3

   Check the connectors and continuity of the harnesses linking the components. Look for any short-circuits to ground, short-circuits to 12V, or open circuits.

4. 4

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

5. 5

   Check the compatibility of program versions, settings, and calibrations, especially if a module was recently updated or replaced.

1. 1

   Read and Analyze

   Connect the CLAAS Diagnostic System (CDS) to identify the nature of the error code and analyze if it is interacting with or generated by another code on the CAN bus.

2. 2

   Inspect Wiring

   Physically inspect the wiring harness running from the MFA (A100) armrest to the EXT (A62) module. Disconnect the harness at both ends and use a multimeter to test for continuity and ensure there is no short to ground or power.

3. 3

   Check Connectors

   Inspect the pins on the connectors for both the A100 and A62 modules for corrosion, pushed-out pins, or moisture ingress. Clean and secure if necessary.

4. 4

   Test Power Supply

   Verify that both the MFA and EXT modules are receiving proper 12V operating voltage and have a clean ground.

5. 5

   Component Replacement

   If the wiring, power, and ground are all within specification, the fault lies within the internal circuitry of one of the modules (most likely the MFA failing to send the signal, or the EXT failing to process it). Replace the faulty component as required.

6. 6

   Clear and Test

   Clear all error codes using the diagnostic tool, then test-drive and operate the tractor to ensure the anomaly does not reappear.