Radiator Cooling Fan Motor: Testing and Inspection

ELECTRONICALLY CONTROLLED VISCOUS DRIVE - 5.9L DIESEL





If the fan assembly free-wheels without drag (the fan blades will revolve more than five turns when spun by hand), do not replace the fan drive. This spin test must be performed when the engine is cool.

If the fan assembly does not free-wheel and a metallic grinding sound exists, replace the electronically controlled fan drive.

NOTE: The following test may take up to 15 minutes to perform.

The engine should be at normal operating temperature.
1. Set the parking brake and verify the transmission is in park or neutral.
2. Set air conditioner (if equipped) and blower fan to OFF.
3. Start and allow engine to reach normal operating temperatures.
4. Stop engine, connect the scan tool and select appropriate model year and engine option.
5. Check for and correct existing DTC's
6. Using Tool 6801, connect pin 1 of the electronically controlled viscous fan drive connector, located at the lower fan shroud to battery ground.
7. Using the scan tool, verify that DTC 0480 set.
8. Start the engine.
9. Go to the SENSOR screen and observe the fan speed.
10. Run the engine at 2500 rpm.

NOTE: It maybe take 15 minutes before fan speed increases.

11. The fan speed should increase according to the table below.
12. If fan speed does not increase, replace the electronically control viscous fan drive.





ELECTRONICALLY CONTROLLED VISCOUS FAN DRIVE SPEEDS

13. If the fan speed does increase and there is still a concern, refer to the appropriate Engine Electrical Diagnosis to diagnosis the electronically controlled viscous fan drive control circuit.

CAUTION: If the viscous fan drive is replaced because of mechanical damage, the cooling fan blades should also be inspected. Inspect for fatigue cracks or chips that could result in excessive vibration. Replace fan blade assembly if any of these conditions are found.