While I was fixing the leaks described here , I found a disconnected wire and a terminal that looked like it should take that wire. I hooked them up, and now I get a "Brake Failure" light when I hit the pedal. I'm assuming this is some sort of a pressure switch that reacts to pressure difference between brake system contours.

I checked fluid tank, it was dry. Guess I got a leak. Making the light go out would probably require brake bleeding - the pedal is a bit soft. I don't know where the leak is, though. Where is a common place for brakes to leak on 240's? On my 745 it was the fluid tank grommets.