96 sc2 noises

Ok so I have a 96 sc2 manual with 209k on it. I have a noise, a hi pitched squeal, that started awhile ago (9-12 mo), but only when frist started and would go away in a few second unless I turned the headlights or wipers on, or brake lights, then would last maybe 5-15 sec. Figured it to be the belt slipping , and didn't worry too much since it wasn't all the time. Now, the other day when I left work, it did it, but stayed on for several minutes but finally went away. So, I took a look at the pullies, since this time it didn't have the sound of a belt. I replaced the idiler and the alternator, everything else looked good. Drove for 2 days...fine. 3rd day I woke the neighborhood with this noise again. The tenisonor looks good. I had the pully off, bearings are ok and the assembly seems to keep tension. I also can induce the noise with the a/c, but not all the time.

any help?

also I have this pinging/rattiling noise form the same area while I'm driving, usually under 2k rpm, or if its chuggin a little.

Tske the belt off and start the car for 30 Seconds ONLY!. If you hear the noise still then you will know it has nothing to do with the pulleys or belt and is an internal engine problem. If you dont hear the noise its a belt/pulley issue. How long ago was the belt replaced? The tensioner? At 200K miles it about time some of the original stock parts get replaced.

ok so i replaced the tensionor. noise seems to be gone. but now the battery light comes on intermittingly. ive rechecked all the connections. so before i pull the alt again, what can i do? is there a voltage regulator?