Fuse 4 in the fuse block doesn't provide power, it provides a ground path for the door switch sense circuits for the instrument cluster. When the instrument cluster sense circuits are grounded, the cluster will turn on the interior lights -- the power comes from fuse 26 in the PDC (which gets its power from fuse 15 in the PDC). If you're not getting power from the fuses in the PDC however, you should be getting a message in your odometer readout that says "NO FUSE". If you're not seeing that message on your instrument cluster, then the problem probably lies with either a bad fuse in the #4 slot of the fuse block, or a lack of good continuity to ground between the door switches and ground G300 in the outboard side of the driver's side footwell. If your Jeep's previous owner is anything like the one for my '05, you'll most likely find the wires for the switches disconnected if you look up in the footwells.
2000 TJ SE
2005 LJ Rubicon