Ford: transfer case, e4od, transfer case

Question
1991 bronco,302 efi, 1356 electric, e4od tranny.  I'm sure you have heard of this problem but not to this extent.  I've changed the shift motor and the shift module and the thing still doesn't complete the shift into 4 wheel.  If I take the motor apart and put it in 4 wheel manually and assemble the motor in the correct place it will shift back to 2 wheel.  I think that there is a sensor that is not telling it to shift but I can't find which one.  Could you go into detail with this.  The shop could't fix it either. How can I eliminate the sensors so I can find out which one is faulty?  I appriciate this.  Have a good day and make mine better by solving this.  Please ask me questions if you wish.

Answer
Bruce  look on top of your transfur case you should see a  round sensor with vac lines on it let me know if this is present on your trans. if it is remove it and see if it has fluid in it if so replacs it this should take care of your problem if not let me know.