Case IH 518977-08 - VCM – VCM: Vehicle speed anti-tamper checksum not sent by cluster

The Vehicle Control Module is not receiving the expected anti-tamper checksum data packet from the instrument cluster/display over the CAN bus network. This checksum acts as a security measure to prevent unauthorized tampering with the tractor's vehicle speed signal.

• MAGNUM AFS Connect
• Magnum 400 AFS Connect

1. 1

   Verify Cluster Operation: Ensure the instrument cluster (and AFS Pro 1200 monitor) powers up correctly and is displaying data.

2. 2

   Check for Related Codes: Look for other active CAN bus communication codes or voltage supply codes on the VCM (such as 518853-04 through 518859-04, which indicate low supply voltages to the VCM).

3. 3

   Inspect Wiring and Connectors: Inspect the CAN bus wiring harness between the instrument cluster and the UCM/VCM assembly. Look for damaged wires, loose pins, or corrosion at the connectors.

1. 1

   Repair Wiring

   If any physical damage or poor connection is found on the CAN bus lines between the cluster and the VCM, repair the wiring harness or replace the damaged connector pins.

2. 2

   Software/Configuration Check

   Connect the Case IH Electronic Service Tool (EST) to the diagnostic connector (CAN1/ISOBUS). Verify that the instrument cluster and VCM have the latest software installed and are configured correctly to communicate with each other.

3. 3

   Component Replacement

   If the wiring is intact and software is up to date, the fault lies internally within either the instrument cluster failing to send the checksum, or the VCM failing to process it. The faulty module will need to be replaced and calibrated using the EST.