1991 Pontiac Grand Am Battery wont charge

First of all thank you so much for your donation.Taking the battery cable off to test your alternator isn't a good way to test it.Or a safe way for your computer you wouldn't want to damage it by taking the battery cable off.You will need to charge up your battery then get a test light or a multimeter.With the key in the run position check and make sure you have battery voltage to these wire's on the back of your alternator.Battery post red wire,S terminal red wire,and pink and black F terminal.Let me know what you find.

Yes you can donate as many time's as you would like. If you have power to all those wire's then it should be charging. Try this start the car and check all three of those wire's while it's running see if they still have power. If you do then while it's running I want you to check and see how many volt's it read's at the positive and negative battery cable's at the battery. Let me know what you find.