04.5 3500 fan clutch how diagnoise

[Sixpac2]

Hi all,
04.5 3500, DRW, 160,000K I have the factory manual on CD. We are full time RV'ers and tow a heavy fifth wheel.
I looked but can't find how to check the fan clutch if it is working as described. AC is not the best in town and in the past I could hear the fan but last year or so I don't seem too. I also search the forum and all I can find is a dealer DBR Tool.??? The manual does not say anything except look for codes if it goes astray. I have the factory thermostat. Is there a TDR wite up I the TDR magazine on this subject.

Thanks for any help or advice.
Marvin

 

[PWong]

Should find the info from Service manual GROUP 7 COOLING/ENGINE.

 

[Sixpac2]

Anybody else out there have a suggestions??

 

[Bob4x4]

the drb3 will make it much quicker.you can see commanded vs actual rpm,

 

[Bob4x4]

The engine should be at normal operating temperature.

Set the parking brake and verify the transmission is in park or neutral.
Set air conditioner (if equipped) and blower fan to OFF.
Start and allow engine to reach normal operating temperatures.
Stop engine, connect the scan tool and select appropriate model year and engine option.
Check for and correct existing DTC's
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.

Using the scan tool, verify that DTC 0480 set. If it is not set, verify that a good ground is available.
Start the engine.
Actuate engine speed to 2000 RPM..
Go to the SENSOR screen and observe the fan speed.
Run the engine at 2000 RPM until the fan speed increases to 1850 RPM or more for 30 seconds.
NOTE: Fan RPM may ramp up slowly.

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

 

[jmadden]

ELECTRONICALLY CONTROLLED VISCOUS DRIVE - 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 (Refer to 7 - COOLING/ENGINE/RADIATOR FAN - REMOVAL). Note they only free-wheel in one direction....

Check the wiring...used to hear that the fan was cutting the harness that comes off the fan clutch. Likewise check the connection on the lower drivers side of the radiator...have heard it is corrosion prone.

Check for codes...P0480 relates to the fan and could be a fuse issue, but if not can be the fan clutch. What I've seen says measure the resistance of pins one and two on the fan-side... believe it's top row of pins, w/ 1 and 2 being the furthest right... if the resistance is less than 10 ohms, your clutch is bad. More than 10 good. Have also seen resistance between pins 1 & 6 should be >6 and <10 (so range of 6-10).

good luck.