Uh oh..exhaust in valve cover

I've bled mine and have to say it's the easiest brake system to bleed that I've ever encountered because it has it's own power bleeder: the brake pump.

As with bleeding any system, start with a full reservoir. With the car in Ready, open the bleeder, and have your helper lightly press and hold the brake pedal. The pump will activate, bleeding the system. Close the bleeder when the bubbles stop, then have your helper release the pedal. Repeat as necessary. If you're crafty, you can even do it with one person.

 

For 3rd gen brake fluid replacement, the car should be in "invalid mode". How to do it without Techstream is outlined in the Repair Manual, and @NutzAboutBolts has a video on the procedure, pinned at top of 3rd gen maintenance sub-forum. In particular with the front brakes, the video illustrates very clearly (using split-screen) how to sync the pushing of the brake pedal with opening/closing the bleed bolt. He does very short open/close blips of the bleed bolt, never lets the brake pedal bottom out.

I've done it on ours, my wife pushed the brake pedal, and it worked fine, no problems, and the brakes are good and firm. I followed the order in the Repair Manual, which is a little contrary to the video: front/right, front/left, rear/left and rear/right.

The only suction I used was a syringe for extracting old fluid from the reservoir before starting the bleeding. Other than that, I used a kosher bleed screw coupler pushed onto a length of clear tubing, and ran it into a large mayo jar with a hole in the lid.

One wrinkle: there's a somewhat shallow "basket" inside the reservoir that I couldn't figure out how to remove, and it has just a narrow slit if you want to push a suction tube further down. I have a mightvac kit with a bunch of little attachments (including the aforementioned bleed screw attachment), and found one item, a very skinny spigot thing that could be pushed on the hose end, make it far enough through that slit to near-drain the reservoir.

I noted the level at the start, after the driver's door had been opened (note: opening the driver's door activates pump and drops the level some), and then aimed to finish the bleeding with the level about the same, and with a little brake fluid held in reserve, just in case I needed to adust, in the next few days (it never budged). I purchased 2 pints of Toyota DOT3 fluid, and that worked out about right.

All of the above said: if @boa279 is dealing with master cylinder with air in it, maybe regular brake bleeding is not going to work; Techstream and a more involved procedure is required??

Anyway, for what it's worth, I've attached the 3rd gen bleed procedure, the one to use without Techstream.

Addendum: maybe it's ok to just bleed the brakes. The Brake Booster and Master Cylinder install instruction just says "bleed brakes" near the end.

 

The front and rear systems are separate. You bleed the FURTHEST from the master cylinder.
But since the rears on the Prius are electric you do the right front, then left front. Then the right rear then left rear.
You could do the rear first I imagine. Doing the furthest one first, you move the most fluid. I will take less time
each wheel.

 

@NutzAboutBolts does the rears first in the video. But the Repair Manual says to use the order I describe above (f/r, f/l, r/l, r/r). Seems like either will work, I figured to stick with the Repair Manual order.

Just editorial: if you read through the Repair Manual attachment (I posted above), you'll see the the way Toyota describes the bleed order is absurdly obtuse. They repeat the complete bleed procedure text, four times, and buried in each, indicate what wheel it's for, with acronyms "LH" and "RH" sub'd for "left" and "right".

A simple picture would in this case be worth about a thousand words, lol.

 

Each manufacturer comes up with their way of doing something. If you do the procedure the way they
say, you can hardly go wrong.
I always removed the reservoir, wash it out with water, then dry it with air from an air hose, then used brake cleaner
to rinse it out and again use the compressed air. After carefully replacing it I would slowly fill it and then start the bleed.
It was easy to see the clean fluid because I used a clear hose in a clear bottle.
That is the way that worked best for me.
I usually research and find as many different ways of doing something they come up with my own way.
But again, If you do the procedure the way Toyota says to do it, you can hardly go wrong.