My voltage gauge bounces rapidly between 14.6-15.1v. It does it at idle and acceleration, under load or without any load, from start to stop. I swapped alternators, disconnected my voltage module and disconnected everything from the battery(which is a brand new die hard) except the alternator and starter and it still does it. Does anyone have any suggestions? Thanks

 

More often than not fluctuating voltage is the result of a bad voltage regulator. You say you swapped alternators, did the new one come with a voltage regulator or did you use your old one?

 

That is a relatively small amount of fluctuation. You are talking about 0.5 volts. Automotive voltage regulators aren't that precise to begin with. Half a volt of fluctuation is not really cause for alarm. To be honest, that tiny amount could be a sticky gauge or even a loose negative to the gauge.

 

just to update, the problem is fixed and turned out to be a shorted diode on the rectifier.