My battery voltage when the car is on is only at like 12.5 V. So I thought that my alternator had stopped working, but after I got a new one, I still had the same problem. My amp gauge also shows that I'm discharging like 5amps or so when the car is on. I can't figure out waht is going on. Any ideas? my car is a 1970 malibu 350. the alternator is from a 1975 truck, brand new, it is wired for the internal voltage regulator. ok thanks for any comments

On the alternator connector there are 2 wires. One you have jumpered to the large terminal on the back of alternator...correct? Where does the other wire go to? To an idiot light? Sounds like the new alternator isn't starting.

its a 16 brown wire, that was previously connected to the old voltage regulator before I switched the internal ones.
it runs into the wiring harness that is headed to/from the battery.
thanks

If you had it on and it worked and then it quit and another one also won't work in it's place then I'd suspect a bad wire connection or a broken wire. Check that the red wire going to the back of the alternator is still connected to the battery. Also check that the wires are making contact with the terminals in the plug. You could take a test light and touch it to the terminal you have the brown wire going to while revving it a bit to see if the alternator begins to work and the light goes out. You can also touch power momentarily right to that terminal or check that the terminal is at battery voltage as other tests.

Peter

it turned out to be that red wire. It had broken a connection where it exits from behind the radiator. Thanks for the help