Case IH 5913-03 - DEC – Transmission Control Unit (TCU) or Vehicle/Tractor ECU: Transmission Oil Temperature 2 (Transmission Oil Temperature Sump) Voltage Above Normal, or Shorted to High Source

The control module is detecting a voltage signal from the transmission oil temperature sensor that exceeds the normal operating range. This usually indicates an open circuit, a disconnected sensor, broken wiring, or a direct short to a high-voltage source.

• MAGNUM AFS Connect
• Magnum
• Maxxum
• Puma
• Steiger
• MX series
• MX100
• MX135
• T6
• T7
• T8

1. 1

   Locate the transmission oil temperature sensor on the side or bottom of the transmission case/sump and visually inspect the connector for mud, moisture, corrosion, or backed-out pins.

2. 2

   Trace the wiring harness from the sensor back to the ECU, looking for chafing, cuts, or pinched wires that could cause an open circuit or a short to power.

3. 3

   Disconnect the sensor, turn the key to the ON position (engine off), and use a multimeter to check the reference voltage at the connector. It should be 5V; if it reads 12V or higher, there is a short to battery power in the harness.

4. 4

   Measure the resistance across the pins of the sensor itself. If the multimeter reads 'OL' (open loop) or infinite resistance, the internal thermistor has failed.

1. 1

   Prepare machine

   Park the machine on a level surface, engage the parking brake, turn off the engine, and remove the key.

2. 2

   Cool transmission

   Allow the transmission to cool completely to avoid burns from hot hydraulic fluid.

3. 3

   Clean area

   Clean the area thoroughly around the sensor housing on the transmission case to prevent dirt and debris from entering the transmission sump.

4. 4

   Place drain pan

   Place a clean drain pan underneath the sensor location to catch any transmission fluid (Hy-Tran) that escapes.

5. 5

   Disconnect harness

   Disconnect the electrical harness from the sensor.

6. 6

   Remove sensor

   Using the appropriate wrench or deep socket, unscrew and remove the old temperature sensor.

7. 7

   Inspect and prepare new sensor

   Inspect the threads of the new sensor. If it does not have pre-applied thread sealant, apply a compatible hydraulic thread sealant to prevent fluid leaks.

8. 8

   Install new sensor

   Thread the new sensor into the transmission housing by hand to prevent cross-threading, then tighten it securely to the manufacturer's torque specification.

9. 9

   Reconnect harness

   Reconnect the electrical harness, ensuring the weather-pack seal is intact and the locking tab clicks into place.

10. 10

    Check fluid level

    Check the transmission fluid level and top up with Case IH Hy-Tran Ultra if any significant amount of fluid was lost during the swap.

11. 11

    Clear fault code

    Start the tractor and check the display. The active fault code should move to a 'stored' or 'inactive' state, which can then be cleared using the tractor's diagnostic menu or a service tool (like Jaltest or CNH EST).