Case IH PD3 – Engine Control Unit (ECU) or Armrest/Transmission Controller (PCU): Hand Throttle Position Sensor Potentiometer 2 Over Voltage

The signal voltage from the second potentiometer circuit of the hand throttle position sensor is reading above its normal operating range, or the signal wire is shorted to a high voltage source (such as the 5V reference or 12V battery). The ECU will often force the engine into a reduced power 'limp home' mode for safety, and hand throttle operation may be deactivated in favor of the foot accelerator pedal.

• MXM
• MXM Series
• MXM120
• MXM130
• MXM140
• MXM155
• MXM175
• MXM190
• Puma Series
• Maxxum Series
• Magnum Series
• Steiger / Quadtrac Series

1. 1

   Turn off the engine and allow it to cool.

2. 2

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

3. 3

   Verify the power input to the sensor. Check that the 5V reference voltage and ground are present at the connector.

4. 4

   Test the signal wire for a short circuit to a high voltage source (battery positive or the 5V reference line).

5. 5

   Test the potentiometer's resistance sweep with a multimeter to determine if the internal tracks of the sensor have failed.

1. 1

   Ensure the key switch is in the 'OFF' position.

2. 2

   Disconnect the wiring harness from the hand throttle position sensor.

3. 3

   Repair the affected section of the harness.

   Perform this if the wiring harness is damaged or shorting out.

4. 4

   Remove the mounting hardware securing the hand throttle potentiometer to the armrest or dash console.

   Perform this if the sensor itself is faulty.

5. 5

   Install the replacement throttle position sensor and secure the mounting hardware.

6. 6

   Reconnect the wiring harness.

7. 7

   Perform a throttle potentiometer calibration procedure.

   On many Case IH models, replacing a potentiometer requires entering the tractor's 'H-Menu' or calibration mode to teach the controller the new sensor's minimum and maximum voltage values.

8. 8

   Clear the stored fault codes and test the hand throttle for proper operation.