The only way to get true 2-wheel drive would be to replace the transfer case.
you may be losing traction. or u may have a sensor going out
Most four-wheel-drive vehicles are controlled by the transfer case. The transfer case has many years in it. A bad year in the transfer case will cause the vehicle not to engage.
My f150 shifts from 2wheel to 4wheel on the fly, but to use 4low you need to be stopped with your transmission in neutral to engage the low range in my transfer case.
check the wires to the transfer case, what year/model
If the shift lever on the floor won't move to engage there is most likely a linkage problem. If the linkage seems to move and you shift the lever under the dash from 2wd to 4wd and the transfer case does not engage look for a vacuum problem. the lines can be very brittle and break easily. There is a vacuum motor on the transfer case that must work in order to engage the 4wd. if all of these seem to work then the problem is likely to be internal.
Yes, it is a shift on the fly system.
Should be full time 4WD, it engages itself.
if you have to ask this then I would have to guess that your Cherokee is NOT a 4wd model...otherwise the 4wd SHIFTER right beside the regular shifter would be a very obvious clueon how to do this. If what you mean is exactly how and "when can you" then you can engage 4hi at any time moving or stopped but to engage 4low you need to be stopped completely and in neutral. same answers for going back to 2wd.
do you engage 4WD manually or via the button on the dash? if its the latter then your actuator switch is probably bad. tweek
This has a vaccum operated servo; you probably have a vaccum line that has come off to the transfer case.
All that you do if put the shifter in the four wheel drive position.
It should engage when you shift the transfer-case onto 4-hi,or lo. It is actuated by a vacuum valve. If it isn't locking in,then you have either a vacuum leak,the diaphram(on the axle housing) is bad,or the mechanism on transfer-case is defective.