Was doing a basic DIY brake bleed over the weekend before I realized that there's more to it. Should have read up on it first. Never tried to bleed this much quantity out of a system before.
I put 4 new calipers on GS400, bled each one. Added synthetic Lucas DOT4 fluid as it went down. Used a Harbor Freight vacuum bleeder connected to compressor, to draw out fluid. When doing the last one (front) I decided to start the engine while I was doing it.
ABS and VSC lights came on. I'm assuming that ABS brake fluid pressure or level was not happy.

So how do I get these lights to go off and brake system to be happy again? Will a proper full bleed/fill restore the system? Once I get to that point, will I need to erase error codes? Or have I really screwed something up?

 

You should be fine once bled right and full. I wouldn't have ran the vehicle while doing it.. it believes there is a system fault. Take a 2nd person and pressure bleed at each wheel.. But if you went dry on the master while sucking fluid, start with bleeding at the master by loosening the line fittings. Same thing. Person inside holding pedal pressure, crack lines, let air out, tighten, then let up on the pedal. Do it until it's free of air. Then go to the wheels. At this point pressure bleeding will be the only way to get a hard pedal.