Digital dash, radio, gas guage not working

I'd start checking the relays if the fuses are all fine. I wouldn't think it's a simple wireing problem unless there's been modifications to it.

You should be able to pull up a decent wireing diagram that will show you all of the paths leading into the instrament cluster. Using a diagram, you may be able to bypass some of the wireing to isolate the problem.

First step, get a wireing diagram. Chances are, you'll find your problem from there.