Case IH 2328 – TCU: Transmission Mid Speed Sensor Signal Missing

Fault code 2328 indicates that the Transmission Control Unit (TCU) is not receiving a signal from the transmission mid speed sensor (also known as the average speed or CDE speed sensor). This sensor monitors the rotational speed of the intermediate shaft inside the transmission. A missing pulse signal while the tractor is moving or in gear can result in erratic shifting, loss of speedometer readings, and the disabling of auto-guidance and PTO functions.

• Puma/Mid Range Magnum
• Puma 140
• Puma 170
• Puma 185
• Puma 200
• Puma 210
• Puma 215
• Puma 230
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• Magnum 370
• Maxxum 120
• Maxxum 130
• Maxxum 140
• Maxxum 150
• Maxxum 155
• Maxxum 170
• Maxxum 175
• Maxxum 190
• Steiger Series
• MX Series
• TG Series

1. 1

   Verify that the mid speed sensor connector has not been accidentally swapped with the output speed sensor or the engine torque/RPM sensor

2. 2

   Inspect the 3-wire wiring harness leading to the sensor for open circuits or shorts to ground

3. 3

   Ensure the sensor is receiving the correct reference voltage (typically 5V or 8V) from the transmission controller

4. 4

   Remove the sensor and inspect the magnetic tip for heavy metal shavings or debris that could block the signal

1. 1

   Preparation

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and disconnect the battery ground.

2. 2

   Locate and disconnect sensor

   Locate the transmission mid speed sensor on the side of the transmission housing. Disconnect the electrical wiring harness and remove the retaining bolt.

3. 3

   Extract sensor

   Carefully pull the sensor straight out of the housing. Have a shop rag ready, as a small amount of transmission fluid may weep from the port.

4. 4

   Install new sensor

   Clean the mounting port thoroughly. Lubricate the O-ring on the new sensor with clean transmission fluid, insert it into the port, and secure it with the retaining bolt.

5. 5

   Reconnect and calibrate

   Plug the electrical harness back into the sensor. Reconnect the battery, clear the fault codes via the tractor's H-Menu or diagnostic tool, and perform a transmission clutch calibration procedure to ensure the TCU relearns the correct parameters.