my 4x4 is screwed up

Well not mine, but my buddies. Its a 90 XJ with the 2hi, 4hi,n, 4low tranny.
Alright so this is what it does, when his foots off the gas it says part time on the dash (even tho he doesn't have that feature). When he steps on it the part-time light goes off. This is in 4x4 mode, hi and low. We replaces all those vacuum lines thinking that would solve it. It didn't. Any help?

anyone?

Does he have a 242 or a 231 (i think ) t_case?

the transfer case shift pattern you describe is the np231 part time transfer case. the "part time" 4x4 dash light would be normal.
Is the 4 wheel drive engagement working?
could it simply be a faulty vacuum activated switch to the light?
check out this link to diagnosing problems with the vacuum activation system