Case IH tB0 – Transmission Control Module (TCM) / Electronic Management Unit (EMU): Vehicle CAN Chip, Shorted To Low Source

This indicates a critical electrical failure where the Controller Area Network (CAN) communication chip or its associated circuit is shorted to ground (a low voltage source), disrupting communication across the vehicle's CAN bus network.

• MXM
• Case IH MXM 120
• Case IH MXM 130
• Case IH MXM 140
• Case IH MXM 155
• Case IH MXM 175
• Case IH MXM 190

1. 1

   Inspect the vehicle CAN bus wiring harness for chafing, bare wires, or pinch points that could cause a short to ground (low source).

2. 2

   Disconnect modules on the CAN bus one by one to isolate the short. If the short remains when the harness is isolated, the wiring is at fault. If the short clears when a specific module is unplugged, that module's internal CAN chip has failed.

3. 3

   Verify the CAN bus terminating resistors are intact and reading the correct resistance (typically 60 ohms across the network).

1. 1

   Replace the Controller

   Disconnect the battery, remove the faulty Transmission Control Module / EMU, and install the replacement unit.

2. 2

   Perform an H8 Memory Reset

   Once the new microprocessor is installed, a non-volatile memory reset (H8 operation) must be performed on the controller.

3. 3

   Reconfigure the Controller

   After the H8 reset, the controller will likely throw a 'C0' fault code because it is unconfigured. You must reconfigure the controller to the correct transmission type so it can identify whether it is in a 120–155 model or a 175/190 model (which may have 19th gear and creeper options).

4. 4

   H1 Clutch and Synchronizer Calibration

   Warm up the tractor. Hold the High and Low range buttons and start the engine. ''CAL'' will appear in the transmission display. Release the buttons. Set the engine speed to 1200 ERPM. Proceed through the automated clutch calibration steps until ''END'' displays to signify completion.