Case IH 9405 – IC (Instrument Cluster): Loss Of DM1 Message From VCM

The DM1 (Diagnostic Message 1) is a standard CAN bus message used to broadcast active diagnostic trouble codes across the machine's network. This fault indicates that the CAN bus communication has been interrupted, and the receiving module is no longer seeing the DM1 status messages broadcasted by the Vehicle Control Module (VCM).

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)

1. 1

   Check for accompanying CAN bus faults, specifically code 9406 (No CAN Communication From VCM).

2. 2

   Verify VCM power and ground by checking the fuses and relays supplying power to the VCM.

3. 3

   Visually inspect the CAN bus wiring harness running between the Instrument Cluster and the VCM for chafing, pinch points, or melted insulation.

4. 4

   Disconnect the harnesses at both the IC and the VCM and inspect the pins for pushed-back terminals, corrosion, or moisture intrusion.

5. 5

   With the battery disconnected, perform a CAN bus resistance test across the CAN High and CAN Low pins (should read around 60 ohms).

1. 1

   Disconnect Power

   Always disconnect the negative battery terminal before servicing the machine's electrical system or unplugging control modules.

2. 2

   Clean and Reseat Connectors

   If moisture or light corrosion is found in the VCM or IC connectors, clean the pins thoroughly with an electrical contact cleaner. Apply a light amount of dielectric grease and firmly reseat the connectors.

3. 3

   Repair Wiring

   If the CAN bus wires are damaged, cut out the damaged section and solder/heat-shrink new wiring to restore the network's integrity.

4. 4

   Restore Power and Clear Codes

   Reconnect the battery. Turn the key to the ON position and use a diagnostic service tool to clear the inactive codes.

5. 5

   Module Replacement (If Necessary)

   If the wiring harness tests perfectly (continuity is good, no shorts to ground/power) and the VCM has verified power and ground but still fails to broadcast DM1 messages, the VCM has likely suffered an internal hardware failure and must be replaced. Note: A new VCM will require dealer software to flash the correct parameters for your specific machine.