basicly i just put a new battery in my 89 vert about 30 mins ago and it runs fine and everything but at high rpms the volts can jump to 16 on my stock gauges. it doesnt stay there but just is there at my high rpms. i need some help on this one. thanks in advance guys.

 

If the alternator is good. I would take a look at the alt plug. Is it plugged in all the way? Also, the 'S' terminal on the alt needs to see battery voltage. You can pull of the plug to check. One terminal should read nothing (goes to alt warning light) the other should be around 12v or so (do this with engine off). The S5s run the 'S' terminal wire to the battery and I believe it is fused (not sure where the fuse is as I am a first gen guy). If you are seeing battery voltage at the plug, and the plug is making a good connection with the alt, then I would say that the voltage reg in the alt may be bad.

Also check battery terminals, cables, and grounds. If these are in bad shape, you can get the voltage problems that you have described. Hope this helps.

Kent

 

Voltage variations dependant on RPM is a classic case of a malfunctioning regulator (or bad inputs to the reg, such as addict is talking about above)...

Read the battery posts with a good voltmeter while she's idling and compare numbers with the stock gauge also, just in case it's a bad gauge...

 

16 volts says its a bad alt... double check with a multi-meter... if it has anything over 15 volts the regulator in the alt is bad or the alt is wired wrong.