I had the same problem about a year ago. Turned out to be a broken solder connection on the instrument cluster, which I understand is common.

Here are a couple threads for further reading;
http://www.peachparts.com/shopforum/showthread.php?threadid=9845

http://www.peachparts.com/shopforum/showthread.php?threadid=9854

Hope that gets you up and running.


EADG
Cheers for now.