Easiest way is get a test light.One end to ground and car off touch the large wire.If it lights it has batt volts.Now unplug the 2 wire connector and touch the large wire in it if the test lihjt lights its good.now turn on the key and touch the small wire if it lights its good.They have an internal reg.I used to rebuild those all the time at work.Super easy but for the prive of a reman not worth the effort.Id also check the actual volts with a volt meter also.But if you do the test Id say the alt is bad.That or just take it to a parts store and have them check it.Thats an easy alt to remove.Rocky