Case IH PCE – PCU (Power Control Unit) / Transmission Control Module / EDC Unit: 1 CAN Chip, Data Valid But Above Normal Range

The Controller Area Network (CAN) communication chip inside the control module is receiving or transmitting data signals that are technically valid in format, but the voltage or data range is exceeding the normal operational threshold. This is typically caused by a voltage spike on the CAN bus, a short to a high-voltage source, or an internal failure of the CAN transceiver chip itself. Note: The fault code is actually TCE, but is frequently misread as PCE on 7-segment digital displays.

• 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

   Check PCU power supply voltage to ensure it is within normal limits (related codes TD0 or TD8 indicate power supply issues that can skew CAN chip readings)

2. 2

   Inspect the CAN bus wiring harness leading to the PCU for chafing, pinched wires, or a short to a high-voltage source

3. 3

   Read active and stored codes using the tractor's built-in diagnostic H-Menu or the CNH diagnostic switch special tool to verify the fault status

1. 1

   Disconnect Battery Power

   Before servicing the PCU, disconnect the tractor's battery to prevent further electrical damage.

2. 2

   Inspect and Clean Connectors

   Locate the Transmission Control Module/PCU. Disconnect the wiring harness and inspect the pins for corrosion, moisture, or bent terminals. Clean with contact cleaner and reseat.

3. 3

   Test CAN Voltage

   Reconnect the battery and turn the key to the 'ON' position. Probe the CAN High and CAN Low pins at the PCU connector to ensure they are resting at standard CAN voltages (typically around 2.5V - 2.7V for CAN High and 2.3V - 2.5V for CAN Low). If voltage is significantly higher (e.g., 12V), trace the harness to find the short to battery power.

4. 4

   Replace the PCU

   If the wiring harness tests perfectly, the CAN chip inside the PCU has suffered an internal hardware failure. The PCU must be replaced or sent to an agricultural electronics specialist for board-level repair.

5. 5

   Perform Transmission/EDC Calibration

   If the PCU is replaced or its non-volatile memory is reset, you must perform a Transmission/EDC Calibration Set Up Procedure. Start the engine and hold the High and Low range buttons until 'CAL' appears on the transmission display. Set engine speed to 1200 RPM. Follow the H1 Clutch and Synchronizer calibration prompts until 'END' displays, signifying the new controller has learned the clutch fill times.