Case IH 12150 – VCU (Vehicle Control Unit): Fault On CAN Message (Hand Brake EPL Switch Signal)

The control module is not receiving the expected Controller Area Network (CAN) message from the hand brake (parking brake) switch, or the signal data has timed out or failed an integrity check.

• Puma/Mid Range Magnum
• MAXXUM T4E
• Case IH Puma series (115 to 240)
• Case IH Magnum series (180 to 380)
• Case IH Maxxum series (110 to 140)
• Case IH Steiger and Quadtrac series (350 to 620)
• Case IH Farmall series (55C to 120A)

1. 1

   Verify the physical operation of the hand brake lever to ensure it is fully engaging and disengaging the mechanical switch.

2. 2

   Inspect the hand brake switch connector (X121) for loose pins, corrosion, or damage.

3. 3

   Check the brake relay of the parking electronic system (connector X036) and the brake connector of the parking electronic (connector X745).

4. 4

   Perform a continuity and voltage check on the wiring harness between the hand brake switch and the VCU to rule out open circuits or shorts to ground/power.

5. 5

   Use a diagnostic tool to monitor the CAN bus network to see if the VCU_HB_SWITCH state registers a change when the brake is engaged/disengaged.

1. 1

   Safely park the machine on level ground and chock the wheels

   You will be working on the parking brake circuit.

2. 2

   Access the base of the hand brake lever inside the cab to locate the hand brake switch.

3. 3

   Disconnect the electrical plug from the switch and inspect the harness side for voltage and ground.

4. 4

   Test the switch with a multimeter for proper continuity when the lever is actuated.

   If the switch fails to close/open the circuit properly, it is defective and must be replaced.

5. 5

   If the switch tests good, trace the wiring harness back to the VCU and the electronic park lock relays, repairing any damaged wires.

6. 6

   Install the new hand brake switch (if faulty) and reconnect the 5-pin cable connection.

7. 7

   Turn the key on and use the universal controller/diagnostic tool to clear the stored 12150 fault code.

8. 8

   Test the parking brake operation to ensure the code does not return and the transmission engages/disengages the park lock correctly.