Case IH 2387 – Transmission Control Module / Vehicle ECU: 1st shaft speed sensor open circuit of short to battery + Input shaft speed sensor

The control module has detected a voltage irregularity—specifically an open circuit or a short to battery positive (B+)—in the circuit belonging to the transmission's 1st shaft speed sensor (also known as the input shaft speed sensor).

• Steiger T4B
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Quadtrac 450
• Quadtrac 500
• Quadtrac 550
• Quadtrac 600
• Rowtrac 350
• Rowtrac 400
• Rowtrac 450
• Rowtrac 500

1. 1

   Perform a sensor resistance test by disconnecting the sensor and measuring its internal resistance (should be 2700 to 3300 ohms)

2. 2

   Check the wiring harness between the sensor connector and the ECU for continuity to rule out an open circuit

3. 3

   Check between the sensor connector pins (e.g., Pin 1) and a known good ground to identify any short to ground or battery

4. 4

   Inspect the sensor connectors to ensure they are fully seated, undamaged, and that the pins are tight and free of corrosion

1. 1

   Locate the Sensor

   The input shaft speed sensor (Sensor 1) monitors the input shaft speed (engine RPM into the transmission). Depending on the exact transmission variant, it is typically located on the transmission housing.

2. 2

   Test the Harness

   Disconnect the sensor. Probe the harness side to check for a short to battery or an open circuit. If an open circuit or short is found, repair or replace the damaged section of the transmission wiring harness.

3. 3

   Test the Sensor

   If the harness tests good, measure the resistance across the sensor pins. If the sensor reads out of the 2700–3300 ohm specification (or reads as an open loop), the sensor has failed internally and must be replaced.

4. 4

   Software/Controller Verification

   If both the harness and the sensor test perfectly fine, download the correct/latest level of software to the controller. If the fault immediately re-occurs after a re-flash, the controller itself may need to be removed and replaced.

5. 5

   Clear Codes

   Once the repair is made, clear the fault code and operate the tractor to verify the transmission shifts normally and the code does not return.