The idiot lights don't go through the dimmer, so regardless of what the dimmer is doing, those will work. The only exception to this, at least for my '99, are the 4x4 hi, 4x4 lo, and cruise control lights are, for some reason, killed when the dimmer switch is unplugged. Go figure.
The dimmer switch only activates the dome light and cargo lights when rolled all the way up, by sending 12+ to the interior light relay and turning it on, as if one of the doors opened. The rest of the time, the dimmer may as well not even be part of that circuit.
There's little else to go wrong in this circuit, so I'd go to the wreckers yard and get a new one to replace it with. They don't usually go bad, so unless your luck isn't with you that day, you stand a good chance of getting a good one.