were your gauges altered with LED's??? Like taken apart and new ones soldered in or is it an overlay?? If it's an overlay make sure it's glued or stuck all the way down to the old faceplate, that may be stopping the tach needle. If you had LED's put in...good luck, shit could get real expensive real quick if someone F*cked something up. BUT let's look on the bright side. Try disconnecting the Negative terminal for 5 minutes or so on the battery, this will re-set your ECU. It's free, and worth a try.