Case IH 2385 – Transmission Control Module (TCM): Open circuit or short circuit to + BAT of the 3rd gear speed sensor

The engine speed and transmission shaft 3 speed are reading zero, while the voltage at the speed shaft sensor is greater than 4.5 V for 0.3 seconds. This high voltage reading typically points to a broken wire (open circuit) or a wire shorted to a power source, preventing the controller from reading the shaft speed.

• Steiger T4B
• STX Steiger
• Quadtrac
• 350
• 380
• 400
• 435
• 450
• 500
• 535
• 550
• 600

1. 1

   Verify code 2385 is active using the tractor's diagnostic display

2. 2

   Inspect the wiring harness leading to the 3rd shaft speed sensor for any visible damage, chafing, or breaks that could cause an open circuit

3. 3

   Check the wiring circuit with a multimeter for a short to battery positive (+BAT)

4. 4

   Disconnect the sensor connector and inspect the pins for corrosion, moisture, pushed-out pins, or poor terminal tension

5. 5

   Test the sensor's resistance and continuity to determine if the sensor itself has failed internally

1. 1

   Locate the Sensor

   Locate the 3rd shaft speed sensor on the transmission. There are three speed sensors on these transmissions. One is located on top of the transmission towards the back (accessible from the pivot joint under the cab), and the other two are located on the bottom left-hand side of the transmission towards the back.

2. 2

   Disconnect

   Disconnect the electrical connector from the faulty sensor.

3. 3

   Remove

   Remove the sensor retaining bolt and carefully extract the sensor from the transmission housing.

4. 4

   Transfer the Spacer

   Retain the spacer from the old sensor. The three transmission speed sensors use the exact same part number, but they use different spacers in each location to set the correct sensor depth.

5. 5

   Install

   Install the new sensor using the correct spacer to ensure proper depth. Secure the retaining bolt.

6. 6

   Reconnect

   Reconnect the electrical wiring harness.

7. 7

   Clear and Test

   Clear the fault codes via the diagnostic menu and test operate the tractor to confirm the transmission shifts properly (e.g., shifts past 8th gear) and the code does not return.