Case IH 2157 – TCU (Transmission Control Unit): Transmission Lube Pressure Transducer Circuit Signal Out of Range High

The TCU is receiving a signal from the transmission lube pressure transducer that exceeds the normal operating range (> 4.98 V for more than 1 second). This indicates the signal wire is physically shorted to the 5V supply wire, shorted to battery voltage, or the sensor has failed internally.

• Steiger T4B
• Magnum 250
• Magnum 280
• Magnum 310
• Magnum 340
• Magnum 380
• Magnum 7110
• Magnum 7120
• Magnum 7130
• Magnum 7140
• Puma Series (130-240)
• Puma CVX PowerShift
• Maxxum Series (110-150)
• Maxxum 5120
• Maxxum 5130
• Maxxum 5140
• Maxxum 5150
• Maxxum 5220
• Maxxum 5230
• Maxxum 5240
• Maxxum 5250
• Axial-Flow 7120
• Axial-Flow 8120
• Axial-Flow 9120
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230

1. 1

   Verify the transmission fluid level and condition to rule out erratic pressure readings triggered by low fluid or contaminated oil

2. 2

   Inspect the wiring harness and the sealed multi-pin weather-pack connector at the transmission lube pressure transducer for chafing, melted insulation, or water intrusion

3. 3

   Disconnect the sensor, turn the key ON (engine off), and use a multimeter to measure the supply pin on the harness side (should read exactly 5V DC)

4. 4

   With the sensor disconnected, check the voltage on the signal wire. If it reads 5V or battery voltage, the wiring harness is shorted to power. If it reads 0V, the sensor itself is internally shorted

1. 1

   Locate the Sensor

   Locate the transmission lube pressure transducer port on the transmission case (often labeled 'LUBE TD' on the control pressure manifold). On tractors like the Maxxum series, this typically requires removing a small access panel.

2. 2

   Clean the Area

   Thoroughly clean the area around the sensor to prevent dirt or debris from entering the powertrain oil system.

3. 3

   Disconnect

   Unplug the electrical connector from the sensor.

4. 4

   Remove

   Unscrew the defective sensor from the transmission housing. Have a rag ready, as a small amount of transmission fluid may weep from the port.

5. 5

   Install

   Apply a dab of hydraulic-safe thread sealant to the threads of the new sensor (if it does not come with pre-applied sealant or an O-ring) and thread it into the port. Tighten to OEM specifications.

6. 6

   Reconnect

   Plug the wiring harness back into the sensor, ensuring the weather-pack seal clicks into place.

7. 7

   Clear and Verify

   Clear the fault codes from the TCU using the diagnostic menu or a service tool. Start the machine and verify that the transmission oil pressure reads correctly on the cab display without throwing a >4.98V error.