I just purchased a 85 berlinetta with a digital dash and the speedometer,odometer (LED type),and tach (vertical bar type) don't display at all (black),an have not for some time now according to the previous owner.The fuses are all good and have power to both sides using a test light.The wire is connected at the trans tail also.The other gauges (traditional type ,non LED style) seem to work Ok, and the dash lights and dimmer work.Local Chevy dealer says it is not a GM servicable part,and I should take it to a speedo or electronics shop.I'm reasonably well mechanically skilled and I would like to fix it myself if possible.I have read through the last 60 days of this post and have seen a lot of problems with digital dashs in general,but not my perticular one.Any help,insight,links,Ect... would be greatly appreciated.Thanks Dan

 

you ever figure anything out with your gauges yet?

 

My IP didn't work when I bought the car, also. All the vacuum fluorescent displays would not work, but the analog gauges did. It was the power supply board in the IP cluster. It's one of three circuit cards that make up the cluster. I didn't work on it at the time (about 8 years ago), I found a replacement and put the old one on the shelf for a later project. Yeah, it's still there.
To get it fixed, you need to find someone that's good with switching-type power supplies. Even then, it'll be difficult because that board was supplied as an off-the-shelf item to Delco, and I haven't come across anyone with schematics for that board. If anyone has 'em, please let me know!

 

u kno which board is the power supply? and i ve been lookin for schematics as well.

 

The last board.