The alternator in my 90 5.0 notchback won't charge. It's a PA Performance 3g 130 amp unit, about 2 years old and checks out fine at the parts stores tester. My battery is new (interstate) and checks out good also. I've replaced the battery cables and upgraded the alternator cable in the last two years also, all connections are clean. It's like the alternator isn't sensing low voltage, the battery light is on while running and it goes out if I unplug the wire from the alternator so I assume that circuit is fine, no shorting. Is there another bulb that the alternator uses to sense voltage drop? Everything was working fine, then one day i started it up and the battery light came on showing low voltage. Any help would be greatly appreciated.