The first thing to do is connect a test light to the battery negative post, then, with the engine running, touch the probe to the metal housing of the alternator. If the test light lights up, repair the corroded ground cable between the alternator and engine block. The alternator is mounted on rubber bushings on that engine to reduce vibration. Those bushings insulate it so it needs that extra ground strap.
If the light doesn't light up, measure the voltages on the two smaller terminals on the back of the alternator. This has to be done with the engine running. One will have full battery voltage, (around 12 volts). The other one must have less, but not 0 volts. Typically you'll find between 4 - 11 volts. That voltage will tell us where to go next.
Monday, November 3rd, 2014 AT 9:41 PM