Brake Fluid Flush

Hello. I bought a new 2013 Prius C Two in October of 2013, and have used this forum often, but never joined. There are many helpful members and posts to help the do-it-yourselfer. I thought, rather than being someone who just uses the resources, I would post up my experience to maybe help others. Here goes:

I have 92k miles on the car, and like to stay ahead of maintenance (better early than late). After the Toyota Care ran out, I have been performing all the maintenance myself. I researched what I needed to have (tools) and what I need to do to perform the brake fluid flushing. There is a way to disable the electronic braking control without a scan tool, but I opted to go ahead and get the mini VCI and software. I purchased the cable and disc off ebay from a seller who offered unconditional satisfaction (and would pay return shipping), so I figured I couldn't go wrong. The installation was difficult, honestly. I had two lap tops at my disposal - one running Windows 10 Pro and the other Windows XP Home Edition, so I figured I couldn't go wrong. Well, it could have been a lot easier.

If you are thinking of purchasing a Mini VCI, check to make sure it will work with your operating system (including 32 or 64 bit versions). It will save you a lot of time. I spent a total of 9 hours researching how to hack the install to get it to work with Windows 10. I didn't get it running on the XP machine because it will not work with XP Home Edition. I probably could have gotten it to work on the XP machine, but I did not want to stay on the internet too long with this machine (XP is no longer supported), so I just focused on the Windows 10 solution. It works, but that's 9 hours of my life I will never get back! Oh well. If anyone needs a hand with this, I can try to help. The Mini VCI version that came to me was 10.10.018. The version will make a difference too in what will have to be done to get it running. There is quite a bit of info on the web as to how to get it up and running (thank all the people who posted instructions) and I am no genius with computers and got it working.

I purchased 1 liter of Pentosin Super DOT 4 brake fluid and some spray brake cleaner. It is recommended that you have at least 4 bars showing on the battery before you start this procedure. The car will be on, but not ready, so the battery can't easily be charged once the procedure starts. I put the car up in the air keeping it level, and took all 4 wheels off. I took as much of the old fluid out of the reservoir as I could, and then connected my lap top to the car. Then I opened up Techstream, connected to the vehicle, made the appropriate selections in the menu to bleed the brakes, and selected the usual brake bleed procedure and followed the instructions.

It is different than bleeding a normal vehicle (with or without ABS). On the older cars without ABS, it's the old fashioned pump the pedal, hold it down, loosen the bleed screw, tighten it, repeat. With ABS, there are some models that need to cycle the solenoids and motor. With this, it's just strange. The back brakes are easy! With the pedal depressed, you just loosen the bleed screw and watch the fluid go into a catch can (I used an empty water bottle). You have to be careful not to have the bleed screw open for too long. I cycled open (for probably 15-20 seconds) and closed with the bleed screw until all the old fluid was out and I could see fresh come out. Techstream tells you to start with the RR, then go to LR. A 10mm line wrench fits the bleed screw.

On the back brakes, when the bleed is open, you will hear the accumulator discharging (it makes kind of a liquid rushing through a line noise) and the electric pump motor will run. If it runs too long, the system thinks there is a problem (because it can't build pressure back up) and you may hear beeping indicating there is a problem. Don't worry. If you cycle it in short bursts, you won't get the alarm. And, once you're done, any DTC's from the procedure are cleared. Just check with the Techstream to make sure.

Check the fluid reservoir and make sure the fluid level remains high enough. When I started the procedure, I removed as much of the old fluid as I could. Then I started the procedure. I allowed the fluid to run down to the bottom line on the reservoir, then I refilled with fresh fluid. This low level line is actually below the reservoir parting seam (the plastic seam where the top half and bottom half are joined together). If the level drops below the bottom line, the bleeding procedure will become more involved. The fluid must be checked repeatedly. It will go through fluid. I didn't let mine go under the line, and once I was putting the new fluid in for the first time, I overfilled the reservoir knowing I was going to bleed the system and the level would drop. Once you get close to the end, don't do this, or you will have too much fluid in the reservoir and have to drain some out. It's probably okay to overfill it the first time you add new fluid. After that, keep it at the full line.

On the front brakes, it's a little different. The directions on the Techstream left me with questions. It tells you to open the LF bleed screw and pump the brakes. I was like, "What?" On older cars, if you pump the brakes with the bleed screw open, air WILL get in. So, I thought maybe they mean pump the brakes (push down) and tighten the screw. So I was doing that and almost no fluid was coming out. So, I re-read the Techstream instructions and said "It says, open the bleed screw and pump the brakes", so I did it. I looked in the catch can and it had moved quite a bit of fluid through. I did the RF next. The front bleed screw wrench size was 8mm. It was bizarre pumping the brake pedal with the bleed screw open. I only had to do this on the fronts (as the Techstream instructed).

On the front brakes, the accumulator noises and pump running does not happen like the rear brakes. In the beginning when I was opening and closing the bleed screw (the wrong way) I didn't hear the accumulator discharging or the pump running. When I opened the screw and left it open and pumped the pedal, THEN I heard the pump running and I got fluid flow.

Once, the last front caliper is bled, the accumulator is bled. The system does this. All I had to do was click and wait. The accumulator is taken down to zero pressure and then recharged by the motor. You will see the level go up and down in the reservoir. When the accumulator is discharged, the level should be at the max line. When it is charged, it is slightly (maybe 3/4"- 1") below the line. The accumulator bleeding cycles it through zero pressure and a charges state 6 times. Then, it's done!

I had read somewhere (on here I believe) that a member needed to perform and autolinearization after performing the brake bleed. I did not need to. I used all of the 1 liter bottle of fluid to complete the entire procedure. I used slightly more expensive brake fluid that met all of the certifications Toyota wants to see. Incidentally, the fluid was darker than the fluid that was old, which made it easier to tell when I had the old fluid out. I might use Toyota brake fluid next time and just alternate between the Pentosin Super DOT 4 and Toyota fluid so I can use the different color as a visual aid to see where the old and new are.

After driving the car, I can say that all feels good as far as pedal firmness and I did notice I seem to be getting a higher braking score on my Eco screen. I think this has to do with not doing the autolinearization, but I would be guessing. It seems at low speeds, the point at which hydraulic and regen swap duties may have ever so slightly changed. Again, I am not positive on this, it's just a guess. I actually like the way it is now. The transition in my opinion was a little more abrupt before. Now, it feels more normal.

Anyway, I just wanted to post this and see if anyone has any thoughts they may want to share. I tried to provide as much detail and observations here as I could to help the person that is doing it for the first time. It may help give an idea as far as what to expect. Thanks!