Case IH 2293 (520330.12) - DEC – DEC: CAN 2- Bus Mute

A controller on the CAN network has detected an excessive number of transmit or receive errors and intentionally stopped transmitting ('muted' itself). FMI 12 indicates a 'Bad Intelligent Device or Component' or an internal hardware/processing failure, meaning the controller has lost its ability to communicate on the CAN 2 network.

• MAXXUM T4E
• VESTRUM CVX
• Case IH Magnum series
• Case IH Steiger series
• Case IH Puma and Optum series

1. 1

   Perform a CAN Bus Resistance Test: Disconnect the battery and measure resistance between the CAN High and CAN Low pins on the CAN 2 diagnostic port or at the DEC connector. A healthy CAN bus should read exactly 60 ohms.

2. 2

   Verify Power and Ground: Check the main power supply (12V) and ground pins at the DEC harness connector. Look for voltage drops under load.

3. 3

   Inspect the wiring harness leading to the DEC for chafing, pinched wires, or corrosion at the connector pins.

4. 4

   Perform Module Isolation: Disconnect other modules on the CAN 2 bus one by one to see if communication is restored, as another failing module could be flooding the network with errors.

1. 1

   Verify the fault

   Connect a diagnostic tool (Case IH EST or a compatible aftermarket tool like Jaltest) to confirm that 520330.12 is active and that the DEC is unresponsive on CAN 2.

2. 2

   Isolate the DEC

   Unplug the DEC module. Check the connector for water intrusion, bent pins, or pushed-back terminals. Clean with contact cleaner if necessary.

3. 3

   Test the harness

   Perform the 60-ohm resistance test, and check for continuity between the DEC connector and the rest of the CAN 2 network. Repair any broken wires.

4. 4

   Replace the DEC

   If the wiring harness is perfectly intact, terminating resistors are good, and the module has clean power and ground, the FMI 12 code confirms the DEC has suffered an internal hardware failure and must be replaced.

5. 5

   Reprogram and calibrate

   Install the new DEC module. You must use the Case IH Electronic Service Tool (EST) to flash the correct firmware dataset to the new module and perform a transmission calibration procedure before the tractor will operate correctly.