My temperature guage on the dashboard does not work, whats the problem?

The Instrument Cluster on GM cars do go out and need repair. I have done several. You can remove the cluster and send it to a rebuilder. The one I use is SpeedoTach in Concord Calif and they do all the GM Dealership work, and they are very reasonable, i.e it costs about $85 for a rebuild, not bad when you consider a new Cluster is around $1000, but GM does not make them any more, I know because I have tried.