The volts in my girlfriends 04 GTP drop from 14.8 to 11.4 sometimes 11.1 while stopped, when the car is first started, even if the car is already warm. I thought maybe the alternator belt was slipping because it does every 3 seconds ( I counted) and last almost 2 seconds, but when i pulled on it was tight and wouldn't budge. I also tried to turn what the belt sits on but that didn't move either. Hopefully I wont have to replace the alternator because her dealerships is talking at least $600. Has anyone ever experienced this or can help diagnost the problems. TIAfor any input.

Now she is afraid it will cut off so she wont drive it, so now im stuck with it and im footing the gas bill for both

Have you tried turning off all the accessories and see what happens? If you have the key on, but not running, will it do anything similar?

have the alternator, and possibly the battery, tested at your local parts store.

you should be able to get a used alternator for under $100, or a new one for $250, they are very easy to install on the 3800.

When I did this the lights didn't flicker, nor did the volts drop.
I will be taking it in first thing in the morning. If the alternator is bad are there any brands that you would recommend, or am I better off getting a factory replacement from the dealer. Thanks for the feedback

This belongs in Other 3800'*

Do you have any kind of aftermarket stereo, amp, or subs?

Sorry for posting in th wrong place No everything is stock. It turns out the alternator is going bad, but I have books to buy for school so it will have to wait a week or two