Case IH 12132 – Vehicle Control Unit (VCU), Powertrain Control Unit (PCU), or Steering Controller: CAN – bus off / NO CAN - Bus OFF

Severe communication failure on the Controller Area Network (CAN) bus. A module has experienced too many transmission or synchronization errors and has taken itself offline to prevent further disruption to the network.

• Puma/Mid Range Magnum
• MAXXUM T4E
• Puma Series (165, 180, 195, 210, 225 CVX)
• Magnum Series (MX210, MX230, MX255, MX285)
• MXM Series (MXM 120 through MXM 190)
• Farmall Series (40, 45, 50 with Cab and CVT Transmission)

1. 1

   Verify power to the controller by checking for a disconnected battery or blown fuse causing the node to drop offline

2. 2

   Inspect the CAN wiring harness to see if it is disconnected, shorted to a high/low source, or physically damaged

3. 3

   Check the VCU or connected peripherals (like the Throttle Dial) for any obvious defects

4. 4

   Turn the ignition switch to ON, access the diagnostic menu (e.g., H8 or HC menu), and review freeze-frame data or secondary codes (like 12133, 12142-12150)

1. 1

   Isolate the Fault

   Disconnect modules on the affected CAN bus one by one to see if the bus voltage returns to normal, which isolates the shorted or failed module.

2. 2

   Repair Wiring

   If the wiring is disconnected or damaged, repair the CAN High and CAN Low wires, ensuring proper twisted-pair integrity.

3. 3

   Replace Faulty Module

   If the wiring is intact but a specific controller (like the VCU) has failed internally, replace the module.

4. 4

   Clear Codes

   Use the tractor's diagnostic menu (e.g., the HC menu) to erase all stored error codes. Note: Clearing some modules via the H8 operation will reset all EEPROM values back to default.

5. 5

   Recalibrate Systems

   Because clearing the EEPROM erases calibration data, you must perform system calibrations. This includes calibrating the steering angle sensor (crucial for AFS AccuGuide), the proximity sensors, and the front suspension potentiometers.