1992 Corvette c4 electronic ignition, tach reads "0", fuel gauge reads "0"; The charging system is intermittent since a voltmeter on the battery will read 12v, and sometimes 14.5v. The alt tested good, and the dash voltmeter reads when a voltage is applied to it. Where is the tach filter located and how can I test it? What is the wire path from the dash to the point the voltmeter gets its voltage?

 

Iirc the inputting for the cluster is feed bye the bcm. You will have better diagnostic at corvette forum.