CLAAS Id7886h / 7886h – EXT (A62) - External function module: Communication failure on the ISO CAN bus network

The EXT module no longer transmits any messages on the ISO CAN bus due to a number of CAN frame errors too high on the ISO CAN bus.

• Axion 800
• Axion 810
• Axion 850
• Axion 920
• Axion 950
• Arion 510
• Arion 530
• Arion 540
• Arion 550
• Arion 620
• Arion 640
• Arion 650

1. 1

   Inspect the physical wiring harness for the ISO CAN bus.

2. 2

   Verify the external function module EXT (A62) is receiving power and functioning.

3. 3

   Check the sources of energy to the EXT module, including all relevant fuses, power supply lines, and ground connections.

4. 4

   Check the connectors and continuity of the harnesses linking the EXT module to the rest of the CAN network.

5. 5

   Test the ISO CAN bus lines for short-circuits to 12V, short-circuits to ground, or open circuits.

1. 1

   Document and Analyze

   Note all error codes present on the tractor's Cebis terminal or diagnostic tool. Analyze the interaction between these codes, as a voltage or ground issue can generate multiple CAN bus errors simultaneously.

2. 2

   Inspect Wiring and Connectors

   Locate the EXT (A62) module. Disconnect its harness and inspect the pins for corrosion, pushed-out pins, or moisture.

3. 3

   Test the ISO CAN Bus

   Using a multimeter, test the ISO CAN bus wiring for proper resistance (typically 60 ohms across CAN High and CAN Low with batteries disconnected) and ensure there is no short to ground or short to power.

4. 4

   Repair Wiring

   If a short, open circuit, or damaged connector is found on the ISO CAN bus network, repair or replace the affected harness section.

5. 5

   Software/Calibration Check

   Check the compatibility of the program versions, settings, and calibration of the EXT module.

6. 6

   Clear and Retest

   Clear all error codes from the system. Cycle the ignition and operate the tractor to see if the anomaly returns.

7. 7

   Replace Module

   If the wiring, power, and grounds are all intact and the error persists, the EXT (A62) module has suffered an internal failure and must be replaced.