A: Typical GM alt. When the brushes get worn down, the light can come on after the battery is fully charged or a loose diode trio will mess with it too. The regulators are pretty chicken feed on those too. From: Teamamc <teamamc@xxxxxxxxxxx> Subject: Alternator idiot light To: mail@xxxxxxxxxxxx Message-id: <004301c4db16$1e483a70$6400a8c0@quicker> I have an 81 Eagle SX4. Yesterday on my way home the alternator idiot light came on. I pulled the Positive cable with the engine running and the alternator is still charging. I notice that when the engine idles really slow to the point of stalling the light goes out. When I turn the key to start the Car the ALT is out. after the engine starts the ALT light comes on. Any Idea on what would cause the aLT light to reverse itself. Thanks Bryan