Case IH tCA – PCU (Power Control Unit): CAN In PCU, Shorted To Low Source

This indicates that the Controller Area Network (CAN) communication circuit connected to the PCU is experiencing a short to ground (low voltage source). This prevents the module from properly transmitting or receiving data on the CAN bus network.

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

1. 1

   Inspect the CAN bus wiring harness leading to the PCU for chafing, bare wires, or pinch points that could cause a short to the tractor's chassis (ground)

2. 2

   Disconnect the PCU and inspect the pins for corrosion, moisture, or bent terminals that could bridge the CAN lines to a ground pin

3. 3

   Isolate the short by disconnecting the PCU to see if the short to ground on the CAN network clears. If it does, the PCU is internally shorted. If the short remains, the wiring harness or another connected module is at fault

1. 1

   Resolve the Short

   Repair any damaged wiring in the CAN harness. If the PCU is internally shorted to ground, remove and replace the Transmission Control Module / PCU.

2. 2

   Module Replacement

   Install the new or remanufactured PCU and reconnect the wiring harnesses.

3. 3

   Transmission Calibration

   If the microprocessor/PCU has been replaced, or non-volatile memory reset, a Transmission/EDC Calibration is strictly required. Place all shift levers in neutral and block the wheels. Hold the High and Low range buttons and start the engine. Release the buttons when "CAL" appears on the transmission display. Set the engine speed to 1200 ERPM (± 100). Follow the on-screen prompts to calibrate the clutches and synchronizers until calibration is complete and no error codes appear.