tightened the alt belt today light still on.was told that if you diconnected the pos battery cable while the car was running and it quit meant that the alt was bad,well i did that and the car kept running.the light is barely on at idle but brightens as you increase rpms. any ideas?

Tom :could it be the diode going in my alt or where you replying to Kneedamages post. if it is the diode is it replaceable or do you need a new alt.