Case IH 2383 – Transmission Control Unit (TCU / UCM) or Electronic Park Lock (EPL) controller: Parklock - potentiometer signal too low

The voltage signal returning from the Electronic Park Lock (EPL) potentiometer to the controller is below the minimum expected threshold. This typically points to a short to ground in the signal wire, an open circuit in the 5V reference wire, or a complete internal failure of the potentiometer itself.

• Puma/Mid Range Magnum
• Puma Series
• Puma 125
• Puma 140
• Puma 155
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225
• Puma CVX
• Puma CVT

1. 1

   Inspect the wiring harness leading to the park lock actuator and potentiometer on the transmission housing for chafing, pinched wires, or melted insulation.

2. 2

   Disconnect the sensor and turn the key to the ON position to verify a steady 5V reference signal and a good ground at the connector.

3. 3

   Test the signal wire from the sensor connector back to the transmission controller for continuity, and check for a short to ground (which causes the signal too low condition).

4. 4

   Test the potentiometer's resistance sweep with a multimeter while manually actuating the mechanism to check for dead spots or an open circuit.

1. 1

   Power Down

   Turn off the tractor, engage wheel chocks (since the park lock is malfunctioning), and disconnect the battery.

2. 2

   Locate the Sensor

   Locate the Electronic Park Lock actuator assembly on the side of the transmission housing.

3. 3

   Remove the Sensor

   Disconnect the electrical harness from the park lock potentiometer. Remove the retaining bolts holding the sensor/actuator cover in place and carefully extract the sensor.

4. 4

   Install the New Part

   Install the replacement potentiometer, ensuring it aligns correctly with the park lock actuating shaft. Tighten the retaining bolts and reconnect the electrical harness.

5. 5

   Calibration

   Reconnect the battery. You must perform an Electronic Park Lock (EPL) calibration (often listed as Calibration H1) using the Case IH Electronic Service Tool (EST) or via the tractor's onboard diagnostic monitor so the controller can learn the new potentiometer's voltage limits.

6. 6

   Clear Codes

   Clear the fault codes and test the park lock engagement/disengagement to ensure normal operation.