CLAAS Id7890h / 7890h – EXT (A62) - External Function Module: CAN bus communication error regarding engine speed

The external function module has received no information from the engine, or it has received an invalid engine speed signal for more than 5 seconds over the Bus CAN. As a result, the engine speed information is not available on the 7-pin ISO connector.

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

1. 1

   Check the CLAAS vehicle CAN bus network for short-circuits (to 12V or ground) or open circuits in the wiring harness.

2. 2

   Verify the status and connections of the bus CAN network communication module BDG (A103), the ENG (A15) module, and the external function module EXT (A62).

3. 3

   Verify the physical condition of the 7-pin ISO connector where the engine speed information is routed.

4. 4

   Verify all related fuses, power supply lines, and ground connections for the involved modules.

5. 5

   Verify the compatibility of program versions, settings, and calibration across the CAN network.

1. 1

   Visual & Multimeter Inspection

   Inspect the wiring harness connecting the EXT (A62), BDG (A103), and ENG (A15) modules. Use a multimeter to test the CAN bus lines for continuity, ensuring there are no open circuits or short-circuits to ground/power.

2. 2

   Power & Ground Verification

   Test the power supply and ground pins at the connectors for the EXT, BDG, and ENG modules. Replace any blown fuses or repair damaged ground straps.

3. 3

   ISO Connector Maintenance

   Clean and inspect the 7-pin ISO connector. Look for pushed-out pins, corrosion, or moisture that could interrupt the engine speed signal.

4. 4

   Module Testing/Replacement

   If the wiring, power, and grounds are all within specification, the fault lies within one of the modules failing to transmit or process the CAN frames (most likely the EXT or BDG module). Replace the faulty component as required and perform any necessary software calibration.