Case IH 24 – TMF (Tractor Multi-Function), ARM (Armrest), or AUX (Auxiliary Remote) Controller: Communications Lost with Instrumentation Controller

Indicates a Controller Area Network (CAN) bus communication failure where the Armrest or Tractor Multi-Function controller has lost its data link with the tractor's main instrumentation cluster or performance monitor display.

• Magnum
• Case IH MX Magnum Series
• Case IH TG Series
• Case IH Puma Series
• Case IH Steiger / STX Series (STX 275, 280, 325, 330, 380, 430, 480, 530)

1. 1

   Verify that the tractor model configuration is correct in the instrumentation controller (ST MODEL parameter must match).

2. 2

   Inspect wiring harnesses and CAN bus connections between the Armrest/TMF controller and the Instrumentation Controller for dust or moisture corrosion.

3. 3

   Check power supply to the Instrumentation Controller, including blown fuses or faulty relays.

4. 4

   Verify that the correct software is installed in the controllers.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts during inspection.

2. 2

   Harness Inspection & Cleaning

   Locate the CAN bus wiring harness connecting the Armrest Controller to the Instrumentation Controller. Disconnect the plugs at both modules. Clean the pins and connectors using a dedicated electrical contact cleaner to remove any dust or moisture corrosion.

3. 3

   Continuity Testing

   Use a multimeter to test the continuity of the CAN High and CAN Low wires between the two controllers. Repair or replace any damaged or chafed wire segments.

4. 4

   Reconfigure the Controller

   If the wiring is intact, reconnect the battery and connect the Case IH Electronic Service Tool (EST). Navigate to the controller configuration menu and verify/re-enter the correct "ST MODEL" parameter for the tractor.

5. 5

   Clear Codes

   Once the configuration is verified and connections are secure, use the EST or the programmable display's "Reset" button to clear the fault codes.

6. 6

   Component Replacement

   If the fault immediately returns and the wiring is 100% verified, the fault lies within the hardware of either the Instrumentation Controller or the Armrest Controller, requiring replacement.