Case IH 2602 – Transmission Control Unit (TCU) or Tractor Controller (TRC): Transmission Oil Temperature Too High

Indicates that the transmission or CVT hydrostatic oil is overheating. Note: Official documentation states code 2602 designates 'Low power supply voltage 12VT1' or 'Failure in the hydraulic oil level switch', but the provided diagnostic procedure addresses transmission oil overheating.

• VESTRUM CVX
• Magnum Series (Tier III and Tier IV models e.g., 215, 235, 245, 275, 305, 340)
• Steiger Series (e.g., 280, 350–600)
• Older Magnum Series (7130, 7150, 7250)
• Puma / Maxxum / Optum Series (CVT and PowerShift models)

1. 1

   Verify actual temperature using an infrared temp gun or a mechanical gauge on the transmission housing/lines to determine if the oil is actually overheating or if the sensor is sending a false reading.

2. 2

   Inspect the transmission oil cooler and radiator fins for blockages caused by dust, chaff, or oil-coated debris.

3. 3

   Ensure the transmission/hydraulic oil is at the proper level and that the transmission oil filter is not restricted.

4. 4

   Observe the cooling fan while the tractor is at operating temperature. If the fan is not spinning fast enough to pull air through the coolers, the fan clutch may be slipping.

5. 5

   Check the transmission oil temperature sensor resistance and inspect the wiring harness for open circuits, shorts to ground, or shorts to battery power (B+). Clean all major ground cables.

1. 1

   Clean the Coolers

   If airflow is restricted, blow out the transmission oil cooler and radiator. Always clean from the inside out to avoid pushing debris further into the fins.

2. 2

   Service the Fluid

   If the fluid is burnt, degraded, or low, drain the transmission oil and replace the transmission oil filters. Refill with OEM-approved hydraulic/transmission fluid.

3. 3

   Replace the Temperature Sensor

   If the mechanical temperature is normal but the display shows overheating (or if the sensor fails a resistance test), locate the temperature sensor (often screwed into a line or junction block on the left side of the tractor behind the steps) and replace it.

4. 4

   Replace the Fan Clutch

   If the fan is freewheeling or failing to engage when the engine and transmission get hot, remove the fan shroud and drive belts, and replace the fan clutch assembly.

5. 5

   Address Internal Leaks (Advanced)

   If the tractor only overheats under heavy draft loads and all external cooling components are functioning, a technician must perform hydraulic pressure tests to locate internal leaks (such as in the hydrostatic pump/motor or rear drives) that are generating excess heat.