Thanks, I think I have most of the connections cornered now. Not that anyone will ever buy the same controller but I'll document it just a bit just in case.
RED BLUE was the on/off switch. Has to be wired on with a 5 amp or so fuse.
The 20.5 on the label is the shut down battery voltage. Took more then a few minutes of 'nothing I do works' until I got that figured out and applied enough voltage for it to work.
The 3 wire throttle is RED 5V, BLACK Ground, BLUE 0-4V input. Turned out the throttle I got had gone south. I just hot wired it with a AA battery to see it run at ~1/3 speed then put a pot between 5V and 0-4V input to see the range. New throttle on order, should be here next week.
The other connectors look like lights or some other bit of extraneous fluff. Maybe a brake switch with motor off capability. Not sure, don't care.
I'm kind of surprised there isn't a lot of maker stuff on controllers. I've looked in the two controllers I have and the power switching seems to be a bit simplistic. Forty year old designs based 555 timers or op amps. I think it could be done better or at least simpler with just an 80 amp SCR out of a broken microwave oven and a PIC or AVR controller.