Case IH 298967-15 - VCM – VCM: Internal CAN Tx buffer overflow for CAN priority 3

The steering valve's internal controller is being flooded with messages, or it has lost its ability to transmit data on the CAN bus due to a physical bus disturbance, an address conflict, or an internal hardware failure.

• MAGNUM AFS Connect
• Magnum
• Steiger
• Puma
• Optum

1. 1

   Inspect the CAN bus wiring between the VCM and the steering valve actuator for shorts to ground, wire breakage, or chafing.

2. 2

   Verify CAN bus termination by disconnecting the battery and measuring resistance across the CAN High and CAN Low pins at the steering valve connector (should read approximately 60 ohms).

3. 3

   Inspect the electrical connector at the Danfoss PVED-CLS actuator for moisture ingress, corrosion, or bent pins.

4. 4

   Check for address conflicts caused by aftermarket ISOBUS devices that may be causing an address arbitration loss or flooding the bus with priority 3 messages.

5. 5

   Perform a power cycle by disconnecting the battery to fully de-energize the PVED-CLS system, bringing it to a safe state, and see if the module recovers upon reboot.

1. 1

   De-energize the System

   Disconnect the tractor's battery power to ensure the steering system is in a safe state and to prevent shorting the CAN lines during testing.

2. 2

   Clean and Repair Wiring

   If corrosion or wiring damage was found during the diagnostic checks, repair the harness and apply dielectric grease to the connector.

3. 3

   Reboot and Retest

   Reconnect the battery, clear the fault codes using the Case IH Electronic Service Tool (EST) or the AFS Pro display, and test the steering system in AutoGuidance mode.

4. 4

   Replace the Actuator

   If the fault is permanent, repeats, or increases by a count of 1 upon reboot, the PVED-CLS / PVED-CC actuator has an internal hardware failure and must be replaced.

5. 5

   Install New Actuator

   Unbolt the faulty PVED actuator from the steering valve block and install the replacement unit.

6. 6

   Calibrate

   Use the Case IH EST to flash the correct machine-specific firmware to the new actuator and perform a steering valve calibration.