Case IH 3480 – Engine Control Unit (ECU): Coolant Pump PWM actuator: Over Temperature error on the output power stage

The internal circuitry (power stage) inside the control module that sends the Pulse Width Modulation (PWM) signal to drive the engine coolant pump actuator has overheated.

• Magnum
• Steiger
• Puma
• Optum

1. 1

   Check system voltage: Test the battery and alternator output voltage while the engine is running to ensure the alternator is not overcharging the system.

2. 2

   Inspect ECU environment: Verify that the Engine ECU is not being subjected to extreme external heat (e.g., missing heat shields or exhaust leaks nearby).

3. 3

   Test the wiring harness: Disconnect the harness at the ECU and the coolant pump actuator. Check for short circuits to ground, short circuits to power, or high resistance in the PWM signal and ground wires.

4. 4

   Test the coolant pump actuator: Check the actuator for internal shorts or mechanical binding, which can draw excessive current and overload the ECU's power stage.

1. 1

   Resolve Voltage Issues

   If the alternator is overcharging, replace the voltage regulator or alternator assembly before proceeding, as this will continue to fry the ECU.

2. 2

   Repair Wiring

   If the harness test reveals a short or high resistance, repair the damaged section of the wiring harness or replace the engine harness pigtail leading to the pump.

3. 3

   Replace the Coolant Pump Actuator

   If the wiring and voltage are normal, the coolant pump actuator is likely binding and drawing excessive load. Drain the engine coolant, remove the serpentine belt, unbolt the faulty coolant pump/actuator assembly, and install a new one. Refill and bleed the cooling system.

4. 4

   ECU Replacement

   If the pump, wiring, and voltage are all perfectly within spec, the output power stage inside the Engine ECU has suffered permanent thermal damage. The ECU will need to be replaced and flashed by a Case IH dealer with the correct machine software.