I have a strange problem with my 1997 expedtion 5.4. When the 4x4 switch is moved to the 4x4h mode it begins to randomly switch back and forth between A4x4 and 4x4h. I have had this evaluated multiple times by ford and private shops. Most recently the transfer case motor was changed as a result of an old TSB. Problem continues. Anyone have any ideas?
I am new to this forum. I apologize if this topic has been beaten to death already.

Thanks in advance!

 

Is there possibly a vacuum leak? Have you tried a different switch? Both of those options are cheap and will eliminate a lot of guess work.