The needle on the stock voltmeter on the dash of my 89 Iroc Z (TPI 305 5 speed) indicates either just above, or in the red discharge zone when the engine is running. This has been happening intermittently for over a year. Recently, the needle is in the red zone just about all of the time. The alternator is new and the battery is definitely being charged because I can drive anywhere and the car always starts right up. Also, when the engine is not running, the voltage across the battery terminals is about 12.8V and when the engine is running the voltage is about 14.5V. Are the gages known to go bad on these cars? Is this likely a wiring issue? Has anyone else had this problem and if so what solved it?

 

I would expect the gauge to be bad. I would check its wiring connections. If one of the connections is corroded bad or a wire is frayed, you will get a bad reading. You could probe around if the dash open with a voltmeter to test things.

 

Thanks for the help. I fixed it yesterday. The problem turned out to be a bad connection between the threaded post on the gage and the connection to the instrument panel.

Thanks again.