I have a 1988 Trans Am with the digital dash package, Everything worked great when i got the car when i was 14, Now however, My battery died a few months ago and when I replaced it, the computer system in the center of the dash won't read. Its the screen below the System check. It is the unit that displays milage, and has the button to switch between MPH and KPH, avg speed, distance traveled, etc. Nothing on that unit is working..

Where is the computer that operates that unit located, and does anyone have any ideas how to fix it?

A list of things I've checked:

1. Fuses
2. Connectors and Wires
3. Circuits

The backlighting works, but there isn't anything displaying... Please help. Thank you!!!