Does anyone know what the test procedure would be for the fan clutch to verify it is working properly?

 

This info is a combined result of a search done on this site. There are others if
you do the search. I kept it for my use if I had the problem.

Dave

ELECTRONICALLY CONTROLLED VISCOUS DRIVE – 5.9L DIESEL

If the fan assembly does not free-wheel and a metallic
grinding sound exists, replace the electronically controlled
fan drive (Refer to 7 - COOLING/ENGINE/RADIATOR
FAN - REMOVAL).

NOTE: The following test may take up to 15 minutes
to perform 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, backprobe pin 1 of the electronically controlled viscous fan drive connector, with the harness connected located at the lower fan shroud to battery ground.

NOTE: The fan drive control coil is energized to 12 volts at this time.
WARNING: A spark may occur when connecting pin to ground. Be sure that no combustible material is in the area.

7. Using the scan tool, verify that DTC 0480 set. If it is not set, verify that a good ground is available.

8. Start the engine.

9. Actuate engine speed to 2000 RPM..

10. Go to the SENSOR screen and observe the fan speed.

11. Run the engine at 2000 RPM until the fan speed increases to 1850 RPM or more for 30 seconds.

Well, I gave that test a try. I connected a jumper from pin one, Brown with Orange tracer, to ground and turned the ignition on. I connected my scan tool and found no active code. I went and made sure that the jumper was making contact and it was. Still no code. I said screw it and went down the road in it. Well gaaaaallllllllyyyyy, The fan is locked up. I drove about 15 miles and the fan was engaged the entire time. Never logged a fault and when I came back I disconnected it and within about 1/8 of a mile the fan disengaged and all was normal again. I cant figure out why it never logged a fault. I dont know what long term, if any, effects it will have on the ECU or the fan clutch. I dont see where there would be any since this is how it was designed to work, just I am sending the signal now instead of the ECM. I do know that the engine coolant temp was significantly lower and the throtle position was significantly closer to the floor. It does seem to take more fuel to turn the fan but that is to be expected. I dont see why one could not wire in a switch and have themselves a manual on off clutch. I know I am going to do it. And there was no 15 minute wait. As soon as the jumper was installed, the fan came on. After disconnecting it takes a few seconds for the clutch to disengage but nothing to worry about. I dont know if cooler ambient temperatures will affect how this operated due to the viscous oil or not, only time will tell
__________________

 

Very good info!! I am chasing a problem on my truck and will try this tomorrow. I just wanted to verify proper operation.

Thank You!!

 

If you think its not working, get under the truck on the drivers side, front of the engine just under the fan clutch, and find the connector. Squeeze it together to see if its loose. Also look at the wire and make sure it has not come loose from the retainers and cut by the fan.

I put a small tie wrap around mine. Don't know if it was loose, but it started working right after I did that.

Good luck.

Dave