91 prism charging problem

have a 91 prism the alternator wont charge battery alternator checked and is good new battery and starter im confused

Did you check all your fuses? my 90 prism has a trio fuse block right off thebattery post and one of them is an 80 amp fuse for alternator.........then if that is not it then check hot wire coming off the alternator to make sure there is indeed vo;tage coming out of it....somewhere between 13.4---14.4.........if there is then you are losing it somewhere before it gets to battery........if not then you need to find out why the alternator is not getting signal to charge,,,,:2cents: