I thought so too. However I get no idiot light with key on engine off. The idiot light circuit is good because when i ground the wire with the key on, the idiot light comes on. And, when i turn the key on, the wire has a voltage signal that would excite the regulator like it should. I have not tested with engine running because there are other things to be finished before starting the engine.Don't quote me, but I think the light should come on in both scenarios.
I can live with no idiot light illumination with key on engine off, but Im trying to make sure it will in fact illuminate with engine running and alternator failure.