Case IH 2603 – Transmission Control Unit (TCU) or Body Control Unit (BCU): Transmission Oil Temperature Too Low

This fault indicates that the transmission fluid temperature is below the minimum threshold required for proper operation (below 5 °C) or calibration (below 60 °C). The transmission may stay in neutral, and the system will require a restart or a warm-up period before allowing gear engagement or calibration.

• VESTRUM CVX
• Steiger
• Puma
• Magnum
• Maxxum

1. 1

   Verify operating conditions: starting the tractor in cold weather causes high oil viscosity, which can naturally trigger this warning until the fluid warms up.

2. 2

   Inspect the transmission temperature sensor circuit wiring for an open circuit or a short to ground.

3. 3

   Use the Electronic Service Tool (EST) to check the temperature sensor's live readings. If the engine/transmission is at operating temperature but the sensor reads cold, the sensor has failed.

1. 1

   Warm up fluid

   If the oil is genuinely cold, simply increase the engine speed to heat up the transmission oil and repeat your operation or calibration. If the sensor is proven faulty, proceed with replacement.

2. 2

   Locate the sensor

   On Case IH Magnum models, the preferred location for the transmission temperature sensor is on the side of the transmission case, in front of the RH axle, about a foot up from the bottom of the case.

3. 3

   Drain fluid

   Place a catch pan underneath and drain the transmission fluid (ATF/hydraulic oil).

4. 4

   Disconnect wiring

   Disconnect the electrical connector from the temperature sensor.

5. 5

   Remove sensor

   Remove the retaining bolt and lock plate holding the sensor in place, then pull out the old ATF temperature sensor and discard the O-ring.

6. 6

   Install new sensor

   Coat a new O-ring with clean transmission fluid and fit it to the new sensor. Install the sensor into the transmission case and secure it with the lock plate and bolt. Torque the bolt to 11 N·m (8 ft·lbf).

7. 7

   Reconnect and refill

   Reconnect the wiring harness and refill the transmission with the specified Case IH hydraulic/transmission fluid.