My Corolla's battery light won't turn off. Any idea why?

How’s this? THE ALTERNATOR!!! And I won’t charge you the $80.
With an alternator, it’s either giving out the wrong amperage, or the wrong voltage. You gotta change it. Good news: it’s not that hard, and the part is probably less than the $80.
Also, if you are running your car with a good battery, you are slowly killing it. Replace the alt.

Take your vehicle to AutoZone. for FREEEEEEE, they will test your battery and alternator with their computer. its FREEEEEEEEEEE.

You can also tell the guy what specific variation of Corolla you own and they should find the exact alternator you need, or you can even punch in your car at the website (advanceautoparts.com) (Advance and Autozone are clones, like Chevy and GMC) and search results begin with parts that work specifically with that car.

I say “should” because I have a ‘90 Pontiac and they don’t have either a valve cover oil breather or replacement filter that will actually fit. It’s my TGP, which makes it “special.”

@Fred931 very nice paint on that Pontiac.

Thanks for the info guys.

My brother-in-law (a car guy) actually told me the quick and easy test to see if it’s the alternator (in case you are ever in need for the info). He said turn the car on and while it’s running, pull the positive terminal off of the battery. If the alternator is bad, it will shut off immediately. If the alt is good, it will continue to run (since the battery essentially starts the car, and the alternator keeps it running).

To Autozone I go!

Pick up a VOM at Radio Shack and measure the voltage across the battery terminals while the car is running. You should see between 13.8 and 14.4 volts If it’s lower than that (it should be no lower than 12v if the battery is charged), your alternator or regulator (they are usually integrated now) are not working properly.