Battery Light on again

Aloha!
I have a 98’ 4 cyl Tacoma W 4wd. A few months ago my battery light came on so I bought a new battery and replaced the alternator. Today, my battery light is on again. Did I buy a bad alternator? Or? Any help is bery much appreciated!
Thank you

 

There are a few other threads on this subject with some good information if you search for battery light problems you can find them. They will have all the suggestions for troubleshooting and various causes. The last one I read was found by disconnecting the alternator and starting the truck. The light was then gone. He then hooked it back up and the light was back on isolating the alt as the problem even though it was charging properly. The battery light is controlled by the alt. Another member found the wire that sends the voltage information was loose causing his issue. Be sure to disconnect your battery before messing with the alternator wiring. Good luck in your search hope you solve your problem.

 

My battery light comes on every time I splash through some high water. It would probably stop if I reinstalled factory under carriage plate.