Case IH PCD – PCU (Power Control Unit): 1 CAN Chip, Data Valid But Below Normal Range

Communication error on the Controller Area Network (CAN) bus. The CAN transceiver chip is receiving a data signal that is recognized as valid, but the electrical voltage or data range of that signal is falling below the normal operational threshold.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• TM115
• TM165

1. 1

   Check the battery voltage and the PCU power supply.

2. 2

   Measure the resistance across the CAN High and CAN Low pins with the battery disconnected. A healthy CAN network should read approximately 60 ohms.

3. 3

   Inspect the wiring harness leading to the PCU for chafing, corrosion, or loose connector pins that could cause a voltage drop on the CAN lines.

4. 4

   Look for other active codes like TCE (Data Above Normal Range) or TCF (Shorted to High Source) which can help pinpoint if the CAN wires are shorting to ground or power.

1. 1

   Disconnect Power

   Disconnect the tractor's battery to protect the electronic modules.

2. 2

   Access the PCU

   Locate the Power Control Unit / Transmission Controller.

3. 3

   Clean and Reseat Connectors

   Disconnect the main harness from the PCU. Inspect the pins for moisture, oxidation, or spread terminals. Clean the contacts with a dedicated electronic contact cleaner and apply dielectric grease.

4. 4

   Repair Wiring

   If the diagnostic checks revealed high resistance or a voltage drop on the CAN lines, trace the harness to locate the damaged section. Splice and solder the damaged CAN wires, sealing them with heat-shrink tubing.

5. 5

   Reconnect and Clear Codes

   Reconnect the PCU and the battery. Turn the key switch to the 'ON' position and use the tractor's H-Menu (Electronic Draft Control Diagnostic Test interface) or an electronic service tool to clear the stored fault codes.

6. 6

   Recalibrate

   If the PCU memory was reset or if the controller had to be replaced, you must perform the Transmission/EDC Calibration Set Up Procedure (entering mode HA and calibrating the H1 clutch and synchronizers).

7. 7

   Module Replacement

   If the wiring is 100% intact, the terminating resistors are good, and the code persists, the internal CAN chip on the PCU has failed. The PCU itself must be replaced.