Case IH 2679 – ZTC Controller: Gearbox overtemp

The transmission controller has detected that the transmission oil temperature is very high, specifically reaching or exceeding 98°C (208°F). As a protective measure, the controller will actively reduce the vehicle's speed while this fault is active to prevent catastrophic internal transmission damage, and the operator is instructed to stop the machine immediately.

• Steiger T4B
• Case IH Steiger CVT series
• Case IH Maxxum EP / Multicontroller EP series
• Case IH Puma CVX series
• Case IH Magnum series

1. 1

   Stop the machine immediately and allow the transmission to cool down.

2. 2

   Once cooled to a safe diagnostic temperature (around 30°C / 86°F), check the transmission oil level using the dipstick or sight glass.

3. 3

   Inspect the transmission oil cooler and main radiator for blockages from chaff, mud, and field debris.

4. 4

   Check the transmission oil temperature sensor and its wiring harness for damage, corrosion, or short circuits.

5. 5

   Inspect the transmission fluid for a burnt smell, discoloration, or heavy sludge, which indicates fluid degradation.

1. 1

   Clean the Cooling Package

   Thoroughly blow out or wash the transmission oil cooler and radiator fins to ensure maximum airflow.

2. 2

   Correct the Fluid Level

   If the transmission fluid is simply low, top it up with the approved Case IH fluid until it reaches the correct level on the dipstick/sight glass.

3. 3

   Perform a Fluid and Filter Change

   Place a suitable drain pan under the transmission/gearbox drain plug. Loosen the plug and drain the old transmission oil completely. Remove and replace the transmission oil filter(s). Refill the system with fresh, OEM-approved transmission fluid (e.g., Case IH Akcela Hy-Tran Premium).

4. 4

   Replace the Temperature Sensor

   Locate the transmission oil temperature sensor on the side of the transmission housing. Disconnect the electrical harness connector. Unscrew the old sensor and quickly install the new sensor to minimize fluid loss. Reconnect the wiring harness.

5. 5

   Clear Codes and Test

   Restart the Transmission Control Unit (TCU) by cycling the ignition off and on to clear the fault state. Test drive the tractor under load to ensure the transmission temperature remains within the normal operating range.