battery light stays on, had the bat, alt, and starter checked. what else is it? on 2002 Ford Ranger

battery light stays on all the time. Car runs fine, how can i get it to go out.

Asked by for the 2002 Ford Ranger
Hi There is a diode in the alternator that is like a check valve which if bad will send power back to the cluster and turn the battery light on. I suspect that is the problem.
thank u. i think that was the problem. had the alternator changed since it was under warranty. Thanks again for ur response. chris