Case IH u155 – Transmission Control Module (TCM): Incorrect pressure switch status detected by the pilot head / An incorrect switch state has been detected.

The transmission control system is receiving an implausible, incorrect, or missing signal from the pressure transducer located on the transmission's pilot head.

• Case IH Steiger series
• Case IH MX / TG series
• Case IH Puma series
• Case IH Magnum series
• Case IH Maxxum series

1. 1

   Check that the pressure transducer is physically and securely connected to the correct test point on the pilot head.

2. 2

   Inspect the cable harness connections, wiring, and connectors for corrosion, backed-out pins, or chafed wires that could cause a short or open circuit.

3. 3

   Test the transducer functionality by checking for a standard 5V reference supply and verifying that the signal output voltage scales linearly (0.5V to 4.5V) with pressure changes.

1. 1

   Safety First

   Park the tractor on a flat surface away from obstacles. Firmly apply the parking brake, block the front and rear wheels, and ensure the ground speed display reads zero.

2. 2

   Locate the Sensor

   Locate the transmission pressure transducer on the FPS transmission pilot head.

3. 3

   Inspect and Clean

   Disconnect the sensor pigtail. Clean the connector with electrical contact cleaner and verify the wiring integrity back to the TCM.

4. 4

   Replace the Sensor

   If the wiring is intact but the sensor fails a voltage/resistance test (or is physically damaged/leaking), unscrew the faulty transducer. Install the new OEM transducer (using appropriate thread sealant if required by the specific part) and plug in the sealed weather-pack connector.

5. 5

   Recalibrate the Transmission

   After replacing the sensor or repairing the harness, the FPS transmission calibration procedure must be run. This is controlled by the tractor's electronic management system. Note: If a new control module was fitted or previous calibrations were erased, recalibration is strictly required to clear the code and restore normal shifting.