Typically when this happens the cluster needs to be removed and repaired. When your vehicle is first started, the gauges do a 'sweep test' which verifies whether or not the cluster is functioning properly. It sounds like your cluster fails the 'sweep test'. Out here on the West Coast, we send our GM clusters to a place called SpeedoTach. You can look them up online. They are in Concord, CA and you can send your cluster by FedEx ( That is what I do ). They do all the cluster work for the GM Dealerships out here. Chris, who is the main technician has never let me down and they are very reasonable as well. You won't be able to drive your car much with the cluster out because the alternator won't charge the battery. A new cluster is very expensive and usually hard to come by.