Case IH PD2 – Engine Control Unit (ECU) or Powertrain Control Unit (PCU) / Electronic Management Unit (EMU): Hand Throttle Position Sensor Potentiometer 1 Under Voltage

The signal voltage from the first potentiometer track of the hand throttle position sensor has dropped below the minimum acceptable threshold (under range minimum). The controller detects that the sensor is either disconnected, short-circuiting to ground, or internally faulty, causing the engine to default to a reduced power mode (limp home mode) and disable the hand throttle function.

• MXM
• MXM Series
• Puma Series
• Maxxum Series
• MXU Series
• Quantum Series
• Magnum Series
• Steiger Series

1. 1

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

2. 2

   Verify that the contacts on the ECU/PCU connectors (often labeled 'MX1' or 'GAS' depending on the model) are secure.

3. 3

   Check that the power input to the throttle position sensor is correct by measuring for approximately 5 Vdc between the positive and negative (ground) pins on the sensor's harness connector.

4. 4

   Test the signal wire between the sensor and the ECU for a short circuit to ground or an open circuit (discontinuity).

1. 1

   Preparation

   Ensure the tractor is parked on level ground, wheels blocked, key switch in the 'OFF' position, and the engine is cool.

2. 2

   Removal

   Disconnect the electrical harness from the hand throttle position sensor. Unbolt and remove the faulty potentiometer assembly from the hand throttle lever mechanism.

3. 3

   Installation

   Mount the new OEM potentiometer and secure the fasteners. Reconnect the electrical harness.

4. 4

   Calibration

   Because a potentiometer has been replaced, the non-volatile memory in the controller must be reset to learn the new sensor's minimum and maximum voltage values.

5. 5

   Calibration Execution

   Enter the Transmission/EDC or EMU Calibration mode via the tractor's H-Menu (using the Electronic Service Tool) or by holding specific buttons (like the High and Low range buttons) while starting the engine. Follow the on-screen prompts on the instrument cluster to sweep the hand throttle so the ECU learns the new parameters.