I was actually speaking of the front axle housing maybe having some sort of mechanical failure. I'm not sure beyond that. I'm good with electrical but I would have to break out the schematics and be withing reaching disance to do some real help there. If I get a chance I will look at the schematics just to see if something would jump out at me as being a cause.

 

Watson

I found this quote on another website.

Kind of late on this thread but advanceautoparts.com has the parts. Part numbers are 600-400 $22.99, & 600-401 $38.99. Putting mine in tomorrow. Hope it fixes my issue. My truck goes in to 4x4 but as soon as I put a load on it (in sand for instance) it "bangs" out of 4WD into 2WD. In 4x4 I could climb a mountain in reverse, but not forward... we shall see.

This was in the 97-03 forum.

The 600-400 is also the solenoid on the firewall of our trucks. I already had the updated one with the rain shield, but replaced it anyway during my troubleshooting because it was relatively cheap. The 601-401 checked out to be 97-03 specific. I would be interested to know where the wires from the solenoid (600-400) run to. ECU probably???

The front axle is another possibility I considered. I kind of downplay that possibility based on the lack of failures I could find while searching. I found plenty of shift fork failures for the 97-03 trucks up there. I think FORD updated that part in the NBS 2004. However, it's not like I am finding any issues like I am having either. I might just crack the front differential cover this weekend and see what leaks out.

Thanks again for your thoughts.

 

I have another data point to add.

The front driveshaft stops spinning when the 4x4 disengages on the truck. When it disengages, there is a rattle sound that comes from under the truck. It is hard to pinpoint exactly as I have reserves about getting under a "moving" vehicle. If I had to guess, it would still be transfer case.

So am i back to the transfer case??? Does anyone know how well the dealer diagnostic scanner picks up codes. My edge picks up nothing. I have not seen one check engine or transmission light due to this issue. Even though I put a new engagement motor on it, I might take it off and manually set it 4H and 4L.

 

That would be a dead giveaway that the issue is in your TC and not in the IWE system.

As for codes, remember, not all things that fail on our trucks will throw a code. Sometimes you have to go back to good old fashioned trouble shooting - without the laptop. See if you can find somebody with some Ford TC experience and talk to them.

 

Time to finally put this one to rest. I Bought a used transfer case off ebay and installed it. Everything now works good as new.

I am not quite sure, but my guess would be a bad electromagnetic clutch inside the original unit. That would explain the lack of metal shavings/chunks in the oil and the shop's inability to find something that was mechanically wrong.

Quick question: does anyone currently on the forum take their truck to sand dunes and run it somewhat hard? The only two cases I could find online of broken transfer cases in the 04-08 models are my cousin's truck (04) and mine. Both trucks were driven fairly hard (not jumped) up at the Silver Lake sand dunes in Michigan. I know the member Josiah talked about having 4x4 problems that sounded like mine but I don't think he listed the outcome on the forum and I'm not sure if he is still around.