Found it! Stumbled across the answer in a lotus forum of all places.

Every diagram I have seen, including the one supplied with the bracket kit from Mancini says the warning light terminal is "not used". That's BS apparently , at least for the '85 toyota design. The warning lamp has to be hooked up to a switched source as well, as it is the source of exciter current at low speeds. The internal regulator handles the rest including all of the exciter current at higher rpms. Aside from this hiccup it has been a great upgrade so far. Easy to put on with the mancini brackets, and fairly easy to wire up (now that I have worked out the kinks anyway). It also helps that I stumbled across an former toyo technician at Advance that confirmed the bit about the lamp being the source of low speed exciter current.

Now I have strong out at idle with high beams, foglights, blower on high, and stereo up. The only problem is that my car is an automatic, and since it idles in gear now, my left foot doesn't know what to do with itself since it doesn't have to hold the brake while I feather the gas. There are worse problems to have I suppose.