Hey, I can recreate the old Motorola wont-charge-due-to-burned-out-ALT-light with a modern Delco three-wire! Lucky me.
Just swap out an LED replacement lamp for the normal incandescent. Exact same issue as the old Moto -- doesn't draw enough current to make the alt start!
(The alt will start if you blip the throttle up to 3000 rpm or so, for some reason.)