instrument panel and DIC

This week I have had a problem to arise with my 1994 Aurora, and can't figure out the problem. While driving at night, the dash lights and instrument display go black. I lose the speedometer, gas gauge, temp...etc. It seems okay during the day.
I have changed the fuses 15a under dash, 60a, 20a & 10a in rear for the instrument panel on the passenger side. The 20a was actually blown, but still won't work. A system failure also showed up on the DIC with... oil system level failure...I have even changed the fuse for that. I can't find another fuse or relay for that has anythig to do with this problem. Can someone please help me. I hope it's nothing major.

you mean 1995?

You will find more fuses under the back seat. Just pull up on the front edge of the seat to remove. Sorry, I can't help with specifics.

Sometimes the oil level sensors go bad but the DIC message might suggest that it is disconnected or has a broken wire.

It is a 1995. I did change all of the fuses under the back seat. I even purchased a $20 relay that did not work. There has to be a short somewhere. There are times it not goes on and off. This morning is came on and I drove for a while, then I stopped, got out, started the car again and it hasn't come on since. The fuse on the oil system was blown, so I also changed it. However the DIC is flatlined as of now.
I will probably have to take it to a dealer, and then pay out the butt, to find out what it wrong with it.