I see the gauge volts are below 13 volts.I take a multimeter and test the battery lead in back of the alternator and the plenum as a ground and come up with 14.25 volts.I then go to the battery and the reading there was 14.05 volts off the battery leads.What gives?I noticed the voltage gauge drops whenever I turn on my headlights at night or whenever I cut the radio on.The radio is a stock CD tuner out of a '98 camaro.No BOSE system nor does the car have any amps.Just the radio.I replace the negative battery cable to no avail in the problem and the positive cable looked ok.The serpentine belt is not loose either as I can't turn the alternator by hand.Any thoughts on where to look for a bad connection or power drain?

Ken

3.1 V6

 

Your problem lies behind the dash. My problem is very similar. I'll be driving and then all of the sudden tthe voltage will "drop" to like 11V on the guage. Bang the dash a few times and the guage pops back up to about 14V. There is a connector on the left side of the dash in the back, it's the right side if you're upside down looking at it from under the dash. the connector could be loose and it gives you resistance in the connection, causeing the guage to show a lower voltage than system voltage. I'll see if i can squeeze off a couple of pics for you tonight of the connector since I have the dash apart right now replacing the heater core.

 

Your car now looks like this right?
I also changed every heater core routing hose I could, same time.

 

Pretty Close, it's almost all put back together now though. It was completly drivable 100% of the time that I had the dash apart except for the 20 minutes that it took me to remove teh heter core and to install the new one. So I guess it was completly drivable for 89% of the time that I was working on it.

I'm gonna take a picture fo the under-dash connectors today while I'm at work. I'll post the connections that I'm talking about so that you can take a look and see if that could be the problem for ya'