Case IH 2614 – Transmission Control Unit (TCU) or Instrumentation Controller (INST): Transmission oil temperature sensor is shorted to ground

The control module has detected that the signal voltage from the transmission oil temperature sensor has dropped below the minimum acceptable threshold. This indicates that the signal circuit is shorted directly to a ground source. This happens when the sensor fails internally (creating a dead short) or when the wiring harness insulation rubs through and the bare signal wire touches the tractor's metal chassis. This causes the controller to read an artificially extreme temperature, which can disable transmission calibration or trigger a limp-mode to protect the drivetrain.

• Steiger T4B
• Magnum Series 180-340
• Puma Series 130-240
• Maxxum Series 110-145
• MX100
• MX110
• MX120
• MX135

1. 1

   Locate the transmission oil temperature sensor on the side of the transmission housing near the transmission oil filter.

2. 2

   Perform the unplug test: Disconnect the electrical connector from the sensor, turn the key ON, and check the active fault codes on the display.

3. 3

   Interpret the result: If the code changes to an open circuit code (e.g., 2812 or INST 13022), the sensor has failed internally. If the short to ground code remains active, the signal wire in the harness is shorted to the chassis.

4. 4

   Inspect the wiring harness: Trace the wiring back to the controller, looking for melted loom, pinch points, or areas where the harness rubs against the transmission casing.

1. 1

   Strip back the protective loom

   If the wiring is shorted: Strip back the protective loom at the site of the damage.

2. 2

   Repair the damaged wire

   If the wiring is shorted: Cut out the damaged section of the wire, solder in a new section, and seal it with marine-grade heat shrink.

3. 3

   Secure the harness

   If the wiring is shorted: Reroute or secure the harness with zip-ties to prevent future chafing.

4. 4

   Prepare the tractor

   If the sensor is faulty: Park the tractor on a level surface, turn off the engine, and engage the parking brake.

5. 5

   Clean the sensor area

   If the sensor is faulty: Clean the area around the sensor to prevent dirt from entering the transmission.

6. 6

   Place a catch pan

   If the sensor is faulty: Place a clean catch pan underneath the sensor to catch any residual hydraulic/transmission oil.

7. 7

   Disconnect the wiring harness

   If the sensor is faulty: Disconnect the wiring harness.

8. 8

   Remove the old sensor

   If the sensor is faulty: Using a wrench, unthread the old sensor from the transmission housing.

9. 9

   Install the new sensor

   If the sensor is faulty: Thread the new OEM sensor into the port. (Note: Do not over-tighten. Depending on the part number, it may be an M10x1.0 straight thread or a 3/8"-18 NPT tapered thread).

10. 10

    Reconnect the electrical harness

    If the sensor is faulty: Reconnect the electrical harness.

11. 11

    Top off transmission fluid

    If the sensor is faulty: Top off the transmission fluid if a significant amount was lost.

12. 12

    Verify the repair

    If the sensor is faulty: Turn the key ON, clear the inactive fault codes, and verify that the transmission temperature reads accurately on the cab display.