Chrysler issued a TSB, number 08-15-99 on May 21, 1999 about this problem. I quote from the bulletin:
Erratic, Intermittent Cluster Operation/Intermittent Air Bag Warning light.
This bulletin involves installing a repair harness containing a revised instrument cluster connector.
1998 - 1999 (TJ) Wrangler
1998 - 1999 (XJ) Cherokee
Some vehicles may exhibit an intermittent illumination of the air bag warning light or an intermittent tachometer or speedometer drop out. An Airbag Electronic Control Module (AECM) fault code - "No Cluster CCD BUS" message will be present.
Using the DRB III(R), read and record all active and stored fault codes in the AECM. This condition is caused by minor oxidation of the BUS circuit terminals at the instrument cluster connector. Electrical terminals will show signs of oxidation, which will appear as darkened lines or marks on the cluster male terminals. These often appear as gray or black marks rather than the appearance of oxidation or corrosion usually associated with higher current carrying circuits. This condition will set a "NO CLUSTER CCD BUS" message. The fault code will usually be stored and not active. THIS TECHNICAL SERVICE BULLETIN WILL NOT ADDRESS FUEL OR OIL PRESSURE GAUGE ISSUES. If this fault code is present, either active or stored perform the Repair Procedure.
1 - 05016261AA Cluster Connector Patch Harness
1 - 04856975 Electric Contact Cleaner
2 - 04778570 Heat Shrink Tubing
Reimbursable within the provisions of the warranty.
This sounds like your problem, but the year models stated aren't right for you? quoted from http://autorepair.about.com/library/a/1a/bl550a.htm