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]

Well I did some research on this site and it seems if the grounds are bad it can act up like this. So I checked all 3 of my grounds and they look rusted so I will clean them all up and add a bigger wire from the alternator bracket to the strut tower as this worked for another 6gc member. On my old truck from the 70's there is only one massive ground wire from the battery to the engine block. Would this also work on the celica as it has 3 fairly small cables for grounds. Would one big cable work? Or does the ecu and other systems require multiple grounding points? I am just curious>>Thanks......