I've searched the archives. I've had this problem for a while now.....When driving, my voltage meter will drop to about 10 volts, sometimes get down to the red.....and after a while, just pop back up to 13 volts...never higher though, and then drop back down whenever it wants. The battery is like new, alternator is almost a year old. My battery goes dead every once in a while. I've tightened all grounds and wires to the starter. Here's the kicker though. You figure it's something in the wiring or whatever....but I just swapped from TBI to TPI, so I have a completely different wiring harness, battery cables, ALL wiring. Well I had this problem before and after the swap....the wiring for my TPI is not new, so i guess it's a posibility that there just happened to be a glitch in my old TBI harness and my current TPI harness...but how likely is that? I dont remember having this problem till I got the battery about 6 months ago....but i've had it checked and they say the battery is good....i'm figuring there's a good chance they're full of it though. What could it be?!?!?! Thanks guys.

 

How new is the alternator tho and is it the same one as before the swap ?

Do you notice any signs of the voltage actually dropping that low (dim lights, stalling, stereo cutting out...).

Have you verified the voltage is staying constant at the battery and are not just relying on the gauge to be accurate?

 

The only sign of voltage drop is that my gauge lights will dim down. I figured the gauge could be wrong, but the dimming gauge lights, and the frequent dead battery have assured that the gauge is at least somewhat right. I dont have any kind of gauges or meters to hook to the battery...but I do have a battery charger that I used whenever the gauge shows that the voltage is really low, and when I hook it up to the battery, it will show that it's near dead (it has a meter on it to show you how much charge the battery has).

EDIT: It's the same alternator I had before the swap as well. I've had it almost a year.....and when I first put it on, I didn't have this problem.