If it helps, power from your battery goes to the fuse block in the engine compartment on the drivers side. The positive cable runs into it and from there it gets distributed.That is the way it is on my 94. Yours should be similar.
If you're talking about the power supply that runs the digital displays/climate control panel/etc. this is integral to the IPC (cluster) on the Devilles, has been since 1990 at least. The Seville and Eldo (and variations thereof) had a seperate box that contained this for many model years. In fact, some were labled "central power supply" or such. These were located up above the gas pedal near the center of the dash panel on most cars.
In any case, if yours is bad (digital displays are all out, no working climate controls) you need the cluster repaired/rebuilt.