ABS light on 1999 Jeep Cherokee

SOURCE: 1999 jeep grand cherokee / 4.0 L.

I had a skim module go out in mine in the ignition, and I have a 2001. It's a 100 part, and now it starts fine.

SOURCE: 1999 jeep grand cherokee transmission

This is called limp mode chrysler did this to protect the transmission without leaving the owner stranded by the road,a few things will cause this mainly putting the wrong fluid in the transmission,they use only atf+4,or the govenor pressure sensor is acting up which should cause a check engine light to come on,or the transmission just needs a fluid and filter change,should be done every 2yrs or 36k miles,due the fluid and filter change about 40.00 but if you have the wrong fluid then the whole system needs to be flushed and refilled-transmission-torque convertor,radiator and cooler if equipped and all lines.

SOURCE: 1999 jeep grand cherokee all time four wheel drive will not engage

Sounds like the splines on your transfer case gear are ground down

SOURCE: 4x4 transimission clunks when engaged?

When engaging the 4WD system, you are pulling the lever on the Transfer Case right? Not the transmission, it's a different gearbox.
There were several versions of transfer cases that used both full and part-time 4 wheel drive.
From your description this sounds like a part-time transfer case.
Going with that, it is somewhat normal to hear and feel a mild clunk when engaging 4WD high range, especially if you are at a complete stand-still or under full throttle.
Try engaging 4WD High while slowly rolling at idle - no throttle. It should pull in fairly smoothly.
Once 4WD is engaged it will literally LOCK the front and rear axles together. So do not do it on hard dry pavement.
These older style 4WD systems need a little "give" especially when turning. The engineers assume you are not engaging 4WD unless you are in a somewhat slippery scenario.
Many CV joints, axles, U-Joints, differentials, and transfer cases are damaged and broken by folks who don't understand this.
Reading the owners manual should provide a clearer description of what you've got.
Bear in mind that when you come out of 4WD it may not completely release, again due to hard pavement binding up the axles. You can try this: backing up 10-25 feet in a straight line, or getting one set of wheels on the shoulder or in some gravel. That should allow it to release the transfer case and go back to everyday 2WD high.
I hope this helps.
:)

SOURCE: 1999 jeep cherokee classic: check engine light

yes, don't let us guess. take it in and get it checked out. time is engine wear.