Case IH 2502 (127.03) - DEC – Transmission Control Unit (TCU): Transmission Oil Pressure Sensor Circuit Fault

The system has detected that the Transmission Oil Pressure Sensor's circuit is either open, short-circuited to ground, or short-circuited to a 5V reference, meaning the controller is not receiving a valid pressure signal.

• MAXXUM T4E
• VESTRUM CVX
• Maxxum 5120
• Maxxum 5130
• Maxxum 5140
• Maxxum 5150
• Maxxum 5220
• Maxxum 5230
• Maxxum 5240
• Maxxum 5250
• Magnum 180
• Magnum 190
• Magnum 200
• Magnum 210
• Magnum 215
• Magnum 220
• Magnum 225
• Magnum 230
• Magnum 235
• Magnum 240
• Magnum 245
• Magnum 255
• Magnum 275
• Magnum 285
• Magnum 305
• Puma 165
• Puma 170
• Puma 180
• Puma 185
• Puma 195
• Puma 200
• Puma 210
• Puma 215
• Puma 220
• Puma 230
• Puma 240
• Optum 270
• Optum 300
• Steiger Series

1. 1

   Verify the transmission fluid level and condition to rule out actual low fluid pressure causing erratic readings

2. 2

   Inspect the wiring harness and electrical connector at the sensor for moisture intrusion, corrosion, or physical damage

3. 3

   Test the circuit with a multimeter: verify the 5V reference signal, ensure the ground circuit is intact, and check for continuity to ground on the signal wire (which confirms a short to GND)

4. 4

   Check the fuse panel for any blown fuses related to the transmission control circuits and replace them if necessary

5. 5

   Perform a mechanical pressure test by installing an analog gauge into a regulated test port (often located behind the upper accumulator or on the valve body) to confirm actual transmission pressure against the sensor's electronic readings

1. 1

   Locate the Sensor

   Locate the transmission oil pressure sensor on the transmission case or valve body. On some models (like the Maxxum), reaching it requires removing a small access panel. On others, it may be located on the left side valve body between the fuel tank and transmission, or near the PTO valve.

2. 2

   Disconnect Wiring

   Carefully unplug the factory wiring harness from the sensor.

3. 3

   Remove the Sensor

   Unscrew the old sensor from the transmission port. Have a rag ready to catch any residual hydraulic fluid.

4. 4

   Prepare the New Sensor

   Apply a dab of thread sealant to the threads of the new sensor (unless it comes with pre-applied sealant or an O-ring).

5. 5

   Install the New Sensor

   Thread the new sensor into the port and tighten it to OEM specifications.

6. 6

   Reconnect and Clear

   Plug the wiring harness back into the sensor. Turn on the machine, clear the fault codes from the display, and test the tractor to ensure the pressure readings are accurate and the code does not return.