[s-cars] Is my Alternator gone on my 93 S4?

[Peter]

Gentlemen,

I am having classic systems of a failed Alternator. This morning when I
started the car I noticed after the system check my battery light and break
light continuously stays on but only very faintly. After dropping my son off
at pre-school, I get the battery alarm display. After a few more blocks
everything begins shutting down (radio, ABS, etc) and the car dies.

I had my brother bring me another battery, we install it and I get the car
home. The break light and battery light are still on very faintly.

Since then I have confirmed there is nothing wrong with my original battery
and I have cleaned all the contacts on the Alternator. No change.

How do I confirm if my alternator is definitely toast.

Thanks.

Peter S.