so i have been having issues with my 4wd lately. i have an 89 cherokee I6 and recently its been hit or miss with the 4wd so i got under there and noticed that the cable that runs to the posi-lok on the front drive shaft passenger side the cable link came out and the fitting that acually screws in vibrated out. My question is could that be messing up my 4wd? i looked under and the xfer case is good cuz the front drive shaft is spinning but no power. i took off the dif case and it all looks good any advice will be greatly appreciated. thanks

 

If the "Posi-Loc" isn't locked in place you won't have 4wd, even with the front driveshaft turning. The stock set-up used vacum to engage the shift fork on the split axle to provide 4wd. If the shift fork is not engaged there will be no lock-up in the split axle and therefore you will only have one axle on the front "powered" (driver side) and your differential will compensate by sending the "power" along the path of least resistance which in your front axle would be the split shaft that isn't engaged. If I were you I would pull the vacum shift cover on your axle and re-install your cable. When you do this, my guess is that you will see your shift fork is not engaged.

 

my 4wd had been working i jacked the front end up and it was lockin the driverside wheel. then the iner to outer shaft nuckle that you can see would spin now all that spins is the drive shaft. back to my original question is could that cable cause the 4wd to mess up. if you put the posi on the front end is it no longer a vaccum syster?

 

CMMC is 100% correct. Reconnect your lines for your posi lock and that will engage the fork that locks the inner and outer shafts together.

 

Yes, the Posi lock system can cause an inoperable 4wd system.

If you want to rid yourself of the vacuum activation altogether, try this:
https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/

And, before anyone objects to that, keep in mind the 231 tcase was used on non-disco housings and they had zero issues.