Case IH tD4 – PCU (Power Control Unit) or Armrest Controller: Hand Throttle Position Sensor Potentiometer 2 Under Voltage

The control module is receiving a voltage signal from the second potentiometer circuit that has dropped below the minimum acceptable threshold. This typically points to an open circuit, a short to ground in the signal wire, or an internal failure of the sensor itself.

• MXM
• Case IH MXM Series (MXM 120, 130, 140, 155, 175, 190)
• Case IH MX Maxxum Series

1. 1

   Inspect the wiring harness and the connector at the hand throttle position sensor for physical damage, loose pins, or corrosion.

2. 2

   Verify that the sensor is receiving the correct reference voltage (typically a 5V DC reference) and has a solid ground connection at the connector.

3. 3

   Test the signal wire for Potentiometer 2 between the sensor connector and the PCU/Armrest controller to ensure there is no open circuit or short to ground.

4. 4

   Verify that the throttle potentiometer is not physically out of alignment or mechanically damaged.

1. 1

   Power Down

   Turn off the tractor, remove the key, and allow the system to power down completely to protect the modules.

2. 2

   Access the Sensor

   Locate the hand throttle assembly on the right-hand console or armrest. You may need to remove the plastic trim panels to access the sensor base.

3. 3

   Disconnect

   Unplug the electrical connector from the hand throttle potentiometer.

4. 4

   Remove and Replace

   Remove the mounting hardware securing the potentiometer to the throttle lever assembly. Install the new potentiometer and secure it in the correct orientation.

5. 5

   Reconnect

   Plug the electrical connector back into the new sensor.

6. 6

   Recalibrate

   Turn the key ON. You must enter the tractor's electronic calibration mode (often referred to as the "H-Menu" on MXM series) to recalibrate the new hand throttle position sensor limits.

7. 7

   Clear Codes

   Clear the stored tD4 fault code and test the hand throttle operation to ensure the engine responds correctly and the code does not return.