Case IH tE3 – PCU or CCU: Maximum fan speed low error

The engine's cooling fan is failing to reach the maximum rotational speed commanded by the control unit. This condition is typically caused by a mechanical failure within the viscous fan clutch, a faulty fan speed sensor, or a wiring issue preventing the clutch from fully engaging.

• MXM
• MXM series
• MXM130
• MXM190
• MX series
• MX210
• MX285
• TG series
• TM series

1. 1

   Perform Harness Bypass Test: Unplug the electrical harness connected to the viscous fan clutch. Disconnecting the harness should cause the fan to default to running at full speed. If the fan still does not reach maximum speed, the viscous clutch has mechanically failed.

2. 2

   Verify proper voltage at the fan solenoid/actuator terminals when the system commands cooling (e.g., when the A/C is turned on or the engine is at operating temperature).

3. 3

   Inspect the wiring harness for the fan speed sensor and clutch actuator for any open circuits, shorts to ground, or damaged pins.

1. 1

   Disconnect battery

   Disconnect the tractor’s battery to ensure safety.

2. 2

   Locate clutch assembly

   Locate the viscous fan clutch assembly mounted on the front of the engine (often threaded directly onto the water pump).

3. 3

   Disconnect harness

   Disconnect the electrical harness connector for the fan speed sensor and clutch actuator.

4. 4

   Remove shroud

   Remove the fan shroud or any obstructing guards to gain access to the cooling fan assembly.

5. 5

   Unbolt fan blades

   Unbolt the fan blades from the viscous clutch assembly (if the blades are undamaged and being reused).

6. 6

   Remove faulty clutch

   Unthread or unbolt the faulty viscous fan clutch from the water pump pulley.

7. 7

   Install new clutch

   Install the new viscous fan clutch assembly and torque to OEM specifications.

8. 8

   Reassemble components

   Reattach the fan blades to the new clutch, reinstall the fan shroud, and reconnect the electrical harness.

9. 9

   Verify repair

   Reconnect the battery, start the tractor, and verify that the fan operates correctly and the tE3 code clears.