On the way home from the track last Friday, I would be cruising at about 65 mph and the volt. gauge would rise to about 16 and then back to 14 (back and forth, back and forth, etc.). It did this on the way to my brother's house tonight, too. I know it is not just my gauge since my lights (interior and exterior) get brighter as the gauge goes up. It fluctuates pretty much the entire time I am cruising at a certain speed, but not consistently. Sometimes it will do it for a minute or two straight, then sometimes it will only do it once in a minute.

Is this a sign that my alternator is going bad? It was replaced about a year and a half ago. Do I have a bad ground somewhere? Is there anyway to check that? Anyone ever had this problem before????

BTW-I am also dealing with a overheating problem but I doubt these are related since they don't happen at the same time.

TIA-
Jonathan

 

Obviously check cables, grounds etc first. When it does this tap the instrument panel around the guage and see if it changes. If you see it bounce a little pull off the trim bezel, lens assy and the metal housing. Undo the two screws that hold the guage to the cluster circuit and gently pull out the guage. On the back of the guage you will see two small nuts attached to a piece of white ceramic. That is a resistor, undo the nuts and look where they attach. If the area around where the nuts connect looks black use a pencil eraser and gently clean the contact area until it brightens up. Use a little WD-40 on a clean rag, wipe the area then reinstall the nuts. Don't overtighten or you can crack the ceramic. See if that corrects the problem, otherwise try tapping on the alt with a rubber mallet-you may have a loose internal connection.

 

Thanks for the reply.

I was thinking it was probably just that, but if it was just the gauge, why would it make my lights get brighter? That seems like it is actually producing more voltage...
I checked cables, and other connections around my alternator. They all seem fine. I tried tapping on my alt. with a rubber hammer but nothing seems to happen when it is idling, only when I am going down the road.
Any other ideas????

 

Sounds like the voltage regulator inside the Alt is acting up. Use a DVM to double check the voltage.