4x4 full time wont engage, grinds when shifting out of

I have a 1990 jeep cherokee(XJ) limited. i cannot get the 4x4 to work, when i switch to 4x4 it just grinds. 2wd works fine as well as 4x4 part time, to switch to 4x4 full time i have to put tghe vehicle in neutral to even engage it. all it does then when i shit back into a gear is grind. 4x4 lo also works fine, to get into this gear though i must put the vehicle in neutral to get past 4x4 full time though

if the linkage adjustment is good then you need to pull the transfer case and take it apart to see whats broke. sounds like a issue with the viscous coupler itself maybe a broken snap ring keeping things from lining up properly. your positive its a 242 and not a 231 and somebody put the wrong indicator in the car?

Sounds like a linkage issue to me...I actually just solved a linkage issue tonight on my NP=228, its nice to have a functioning low-range, full-time 4wd is not so hot offroad sometimes....but i have a completely different case than you.

mastertech does have a good idea about making sure which case you have....crawl under the Jeep and there should be a tag, usually red in color, that has the model number of the transfer case...its located on the case itself, usually near the fluid holes.

Also, while mastertech makes a good point about something possibly being broken inside the case, the NP-242 does not use a viscous coupling (thank heavens) but instead uses an open differential for the full-time setting, much like my NP-228 does...so you can rule out one of those being broken.