NP228 operation

Hey all. I have a question about the operation of the selectrac NP228. I have a 86 xj with an auto tranny. Now I am from Ford land but this is my sons XJ. Fulltime and part time has me confused as to how it works. I lifted the rear wheels and engaged 4wd and the other lever was in 4hi. I put the tranny in gear and only the rear wheels turned but i could hear something going on in the transfer case(internal diff). So I shifted it into 4lo and the vehicle wanted to drive with the front and rear wheels. To me the front wheels should be trying to drive in 4hi also. Am I wrong? I need someone to help me here. The only tcases I have ever worked on were parttime tcases so this might be normal. Sorry for the long winded post. Thanks. Oh and I did a search and could not find an answer.

228 has 2wd, 4wd Unlocked High, and 4wd Locked Low.

Hi is a full time option. differential action between the front and rear D-shaft.
Low is Locked Ft/Rear.

DO NOT ATTEMPT TO CHANGE RANGES IN 2WD......MASSIVE damage to the Range Fork will occur.

228 is more desirable than the 229 because the 228 has a gear diff, as opposed to the Viscous Coupler in a 229.

Ok so this is normal action then. So in 4hi the transfer case acts like an open differential. Thanks for the explanation.