Help Alternator ? Options

[bdog_v]

Hello I have a 94 celica gt while idling at night with the lights on heater on and rear defroster the lights will dim and the battery warning light will come on.
I believe the alternator is dieing. It only happens at idle and it comes and goes. I'd like to get it fixed before it leaves me stranded somewhere.
I am wondering?
-Is there a voltage regulator somewhere outside of the alternator or is it internal? I don't want to replace the alternator when it could be something else that regulates voltage.

-Also where is the best place to get an alternator for this beast? Usually these foriegn alternators go for over $100 bones yikes....


Thanks guys...

[bdog_v]

Hello guys I kept all the grounds and replaced them with heavier gauge wire. THis did not make a difference. My voltage reading will slowly drop to 9 volts after idling for a few minutes with all electronics on heater fan on high, rear defroster on, headlights on high beam and the radio has to be on cranked up with my 300 watt amp going. So I don't know if this is a combination of a weak battery and old alternator that can't keep up after awhile? I don't trust those tests at shops as I have the same equipment at home and the alternator reads fine until after a few minutes with all the extra draw from everything being on. So I'd say alternator first as it should be able to keep the vehicle supplied with enough current at idle with everything on even with a weak battery, in my opinion.......

THanks.....