Gen2 bleeding brakes rant.

Hello All, Decided to bleed brakes this weekend since I'm now just a bit over 105kmi. Nothing was wrong with them, just decided that it was time. During the process, I ended up thinking that I screwed something up. The brake 'blob' is a $2400 actuator assembly, a sort of master cylinder, hydraulic, electromechanical monstrosity. If it's already screwed up and throwing codes, it dosen't hurt to keep trying, right? In the end, I managed to get it functional again. Just had to keep trying logical solutions. This car is a great vehicle, no problems yet. I don't expect anything that won't be caused by the "loose nut behind the wheel." AKA, my futzing with it. So, if I haven't bored everyone, the work log below should probably do the job. This rant is a brain dump, partly to myself so that I don't screw it up again. It might be useful to those of you that are going to work on the brakes. The Autoenginuity does support brake bleeding on the gen2, however it still has bugs in the software. When bleeding the rears, you're supposed to put the relays IN! An annoying thing happened while doing one of the rears. If you bleed them you don't have to pump like on 'normal' brake systems. You just push the pedal down, and open the valve. The brake pump takes care of everything. What I learned today is that you should NOT open the thing up too much. If you go too fast, something makes a clunk, folllowed by no pressure to that piston. That, along with a sinking feeling that this is going to be a long day. If you open it again, you'll notice that SOME fluid is coming out, but not much. It's definitely not due to air in the system. What was really scary was that trying to rotate the drum with the pedal depressed caused free rotation on that wheel. Also, the piston pressure sensor remained at a constant value (low voltage.) The other three wheels read proper values. Removal of the relays and pumping the brake pedal rapidly should depressurize the accumulator. I did this many times, well into the beep of death. Interestingly, I think that also unstuck the solenoid. I didn't check this, but decided to grab my other PC. My garage laptop had a much later version on it (I think it's one of the 9x series?) Out of desperation, I ended up going back to version 7.4.3 since I had it on my other machine. I used that last time I did bleeding. After reinstalling the relays, and letting the system pressurize, the piston had full pressure on it once again. I'm not sure if it was the change to an older version, or whether it was the 'no power' depressurization. Repeating this experiment to determine whether something broke in the software, or if it was some other factor is something I don't want to do. Fortunately, brakes are now smooth. For some reason, bleeding the brakes helps alleviate the 'grabbiness' that people attribute to the prius brakes. In fact the reason I do this, along with lubricating, and cleaning up the brake parts (slides, rotors/drums, etc.) is because it seems to make the car much smoother, about as smooth as a non-hybrid. It's important to check your work after you complete the brake stuff. Aside from stepping on the brakes and trying to rotate the wheels, setting up the scantool to watch the sensors is also quite informative. Once buttoned up, a test drive is of course mandatory as well. FYI: I'm sure that the motorcycle people already know this, but for the first time, I have seen the interaction between front and rear brake response in real life. In the order of increasing brake pressure, it looks something like this. The car first preloads all cylinders, and then applies the rear, followed by the fronts. Does this mean that the shoes wear out first when you try to capture maximum regen? This is the second time I've bled the brakes on this car. The first time, the fluid came out pretty much clear on all 4 pistons, this was at the ~50k mark. This time, I noticed that the drivers side front piston came out a bit brown for the first two pumps. All of the other pistons were clean. If anyone has a 'dead' brake actuator, it might be good to do some analysis on it (AKA internal photos) I would certainly like to take a look at the guts of one, there's some really interesting engineering in it. Repurposing it for robotics would be even more fun. A hydraulics package about the size of a 6 pack could be used for all sorts of applications!