How to bleed brake on 2005 Prius?

Hi All,

To be safe one should probably discharge (bleed down) the brake backup capacitor stack. And if they are anything like the caps they are putting in stereos these days - be careful. The last stereo I took apart to fix had like 50 volts on the caps weeks and weeks after it was depowered! The Prius brake backup capacitor looks to be made of something like 36 of those same sized capacitors! You are not going to discarge these with a screw driver, unless you want to loose about 1/2 inch off the end of the screwdriver in a giant plasma ball.

 

No, unless the master cylinder is switched to route the brake fluid to the slaves (brake pedal depressed), the pump running shouldn't affect the slave cylinders. If it did then the brakes would go on every time the pump ran, and they don't.

I put in the caveat in my original post because it's possible the master cylinder could leak a bit, but I doubt it does.

 

damnit this car is pretty technical isn't it? i rather buy 400 bucks worth of tools and service manuals before giving it to the dealership... for now I'll continue using B and avoid using my friction brakes... until i read A offical manual of some sort, all I have is a bleeding procedure manual... i'm sure everyone has that.

 

Whoops, correct

 

Well, that "bleeding procedure manual" is from the official Toyota shop manual. The "only" specialized tool you need is the Toyota THHT or Toyota Panasonic ToughBook. and that would be far more than $400.

Not really a DIY at this point

 

getting my hands the haynes prius manuals i hope it has some answers!

brake pads at the toyo stealership is around 89.99, (labor including caliper overhaul, and front rotor machined with new pads is around 229.99 plus tax)

so instead im going to buy some new pads, then follow hobbits guide to brake maintainence
http://www.techno-fandom.org/~hobbit/cars/brkjob/

so that's a relief some part of the brake system is DIY! i got a caliper pushin tool to push in the piston caliper as i install the new pads, plus some brake kleen and anti seize compound!

 

Hi Phil,

Glad to hear that you are going to replace your brake pads yourself. It makes perfect sense for you to do that part of the work since your local dealer price is so high. What odometer reading do you have?

Certainly the dealer is the correct place to do brake bleed work if you have to replace parts upstream from the wheel cylinders or otherwise allow air in the system and need a complete bleed. However if you are game to try a "flush", keeping air out of the system, I did this on my 2001 last year. I used a rubber suction bulb to remove as much of the old fluid in the reservoir as I could reach. Then I filled the reservoir with new Toyota DOT3 fluid.

Starting from the rear brake wheel cylinders, I flushed each bleed valves one at a time. My procedure was to have my wife turn the Prius to IG-ON then gently press the brake pedal slightly and hold. I attached vinyl hose to the bleed valve leading to a container, then cracked open the valve slightly. A voluminous flow of fluid resulted. Then close valve, release brake pedal, refill reservoir, repeat.

Although this process will not flush old fluid out of certain portions of the brake system, it will purge old fluid out of the brake lines leading to the wheel cylinders. That fluid will be more deteriorated than the rest, being subject to heat produced by the friction brake system.

Although the 2G brake system is more complex than Classic, at the end of the day, from the wheel cylinders' point of view, all that happens is that a pressurized stream of hydraulic fluid arrives. No different than other automobiles.

And what is the worst case? If somehow you allow air into the brake system, this will become immediately apparent. Then you have to tow the Prius to the dealer. This is not the end of the world.

 

can this tool read most if not all toyota codes in addition to testing sensors?

 

I am interested to hear how the brake pad change went.

Also, why cant you just use hobbits procedure to disconnect the brake system, then use a mityvac to suck out the brake fluid at each caliper/wheel cylinder. For those who don't know a Mityvac is a little tool that pulls a vacuum, it can be used for a variety of things, one of those things being brake bleeding.

 

Some one mentions haynes I thought hey why not see what it had to say. to paraphase the brake bleeding section. It is something that is done, just not buy anyone reading this book and with out special tools. But it does let you change the brakes just don't unhook any brake lines. Nothing about disconnecting the battery or disableing any system. It's warning is make sure the hybrid system is off and the smart key is at least 20 feet away. Other than that it appears to be normal brake jobs.

 

When flushing the fluid on my 2001, I first tried using a hand-held vacuum pump as you suggested above, while IG-OFF. Very little fluid came out when using the pump to create a vacuum. My guess is that it is necessary to move the brake pedal a small amount so the fluid in the reservoir has an unobstructed path to flow down to the brake calipers/cylinders.

Using the method described in my prior post, it was really easy to flush a large qty of fluid through each bleed port. I went through 2 small containers of Toyota DOT 3 fluid.

 

Why would Haynes care if the Smart Key is near or far? If the Prius is IG-OFF, having the Smart Key nearby is not going to make the Prius IG-ON or READY so I don't see any safety issue.

The Smart Key kept in close proximity will communicate with the Prius, and that will cause battery drain in both the fob and the Prius. That is the only impact that I can see.

 

Hobbit mentioned early on in this thread, that the brake system will activate itself simply by opening the drivers door. I would not discount Haynes recommendation so off-handedly.

 

What's the backup mechanism which opens up these valves ? Is it mechanical or electrical ?

 

Are brakes usually pretty dependable in Priuses?

 

They last 2X as long as regular cars due to regenerative braking.

 

Writing to post a method I discovered today, that blasts fluid through the system at a satisfying rate. Tools needed
are a jar with 1/4" clear hose, 8'....a 5/16 or 8mm box wrench, and a basic code reader that has the ability to erase codes.

This method differs from others considerably but dam if it didn't work perfect. I tried the others first.

I replaced the abs unit and the system was basically air bound.

Start at right front, cut wheels right. Put bleed tube on and open the bleeder. Put jar where you can see the fluid passing
through the tube. Power has to be on to cut the wheels and leave it on. Press the brake gently, Fluid will pump through,
and at some point will pass through under boost. Push pedal once for one bleed shot. Keep master full.
When the hose runs clear tighten bleeder. Repeat for left front.

You will probably have the tone that indicates brake fail at this point.

Plug in scanner, boot it up for make model and year, and I selected ABS controller, but it is possible that you can just go to
codes/check codes/erase codes. Key in to erase codes. Leave scanner in place set up that way, power on.

Now, get on right rear bleeder with the clear tube, loosen bleeder. Put jar where you can see the hose.
Push pedal gently but continuously, and you will see a gush of fluid and also the abs light will set on the dash.
Erase the code. Now you're ready for another shot. Keep master full.

When all runs clear, go to driver's wheel.

Finish up the job by doing some gravel road brake slams to rattle the air out of abs. Repeat the 4 wheel brake bleed.

 

It's good that you bled things enough to have functional brakes. My only concern is that there are hydraulic passages that could still have air that are not normally used. This is why the Techstream bleed procedure is reccomended- it specifically opens these passages to purge any air.

Posted via the PriusChat mobile app.

 

Indeed. In the Repair Manual (more info), Toyota warns specifically against doing it in any other way: “CAUTION: Bleeding without the Techstream may result in the air not being completely bled. As this can result in an accident, be sure to use the Techstream for air bleeding.”

This isn’t just using the Techstream system to clear diagnostic trouble codes; there is a separate feature (Chassis > ABS/VSC/TRC > Air Bleeding) with three different functions, “Usual air bleeding,” “Actuator has been removed,” and “Master Cylinder or Stroke Simulator has been removed,” that operate the brake system in specific ways.