Case IH PE3 – Engine Control Unit (ECU) or Vehicle/Transmission Control Unit (PCU/CCU): Maximum fan speed low error

This condition occurs when the machine's control system commands the engine cooling fan to run at its maximum speed (usually due to high engine coolant or transmission oil temperatures), but the feedback signal from the fan speed sensor indicates that the fan's RPM is falling below the acceptable threshold for that commanded speed.

• MXM
• MXM series
• Magnum
• Puma
• Steiger
• Axial-Flow series
• 2388
• 5088
• 7140
• 8010
• TM series
• T7 series

1. 1

   Inspect the engine fan drive belt for glazing, wear, or improper tension. A slipping belt is a primary mechanical cause of low fan speed.

2. 2

   Check the fan speed sensor and its wiring harness for continuity, shorts, or open circuits.

3. 3

   Inspect the fan drive mechanism to verify if the viscous fan clutch is engaging properly or if the hydraulic fan drive motor is receiving adequate hydraulic flow and pressure.

1. 1

   Park and secure machine

   Park the machine on hard, level ground. Turn off the engine, apply the parking brake, and remove the key from the ignition.

2. 2

   Access cooling package

   Open the engine cowling/hood to access the cooling package and fan assembly.

3. 3

   Replace fan drive belt

   If the diagnostic check revealed a slipping belt, release the tensioner, remove the old belt, and route the new OEM drive belt. Ensure the tensioner applies correct pressure.

4. 4

   Locate fan speed sensor

   Locate the fan speed sensor (typically mounted near the fan hub or rotor shaft).

5. 5

   Disconnect sensor harness

   Disconnect the electrical harness connector from the sensor.

6. 6

   Remove faulty sensor

   Remove the retaining bolt(s) and pull the faulty speed sensor from its mounting bracket.

7. 7

   Install new sensor

   Install the new fan speed sensor, secure the retaining bolt, and reconnect the wiring harness.

8. 8

   Replace drive motor or clutch

   If the sensor and belt are functioning properly, the hydraulic fan motor or viscous clutch is likely failing under load and must be replaced.

9. 9

   Clear code and verify

   Clear the TE3 fault code using a diagnostic tool, start the engine, and bring it to operating temperature to verify the fan reaches maximum commanded speed without triggering the error.