Brake actuator replacement

oh no!!!! no warranty? how many miles?

check @NutzAboutBolts youtube channel, not sure.

there ight be threads here, but idk

 

Because of the difference in generations, finding any procedure from 2010 through 2015 would be a better bet than trying to follow 2008.

Also, 2008 had an all-singing, all-dancing actuator assembly with the accumulator and pump built in. A gen 3 has an actuator assembly that is separate from the accumulator/pump assembly, which gives you more incentive to pin down exactly which of those is really what you need.

 

Any mystery about how to find the repair manual ought to be cleared up here.

I am not sure where you are getting your numbers. You don't have a Gen 2 in there at all. You have two different numbers for a Gen 3 part, and it's the accumulator ("booster pump"), not the actuator ("booster / master cylinder").

The Gen 3 parts (plural) look like this:



Because they are sold as two different assemblies, you kind of need to know which one is shot before pulling your wallet out.

The Gen 2 part looks like this:



As you can see, because the Gen 2 has the actuator, accumulator, and pump glommed together in one unit, it's less critical to pin down which of those you need before replacement.

 

techinfo.toyota.com

 

The unfortunate choice of two words that are so similar in English, 'accumulator' and 'actuator', has spawned no end of confusion, and even Toyota dealers are not immune. Maybe the Japanese words were easier to tell apart.

That part number you have and photo you posted are of the accumulator assembly, not the actuator, no matter how many web listings you find giving the wrong name for it, even from Toyota dealers. It is also known as the booster pump assembly, and it's the lower of the two line drawings in #5.

The actuator is also known as the "booster assembly" (great, another source of confusion, the only difference between the two names is the word 'pump'), and it is the upper of those two line drawings.

 

search around here for pertinent threads. i found one: TOYOTA BRAKE BOOSTER PUMP CLASS ACTION LAWSUIT FILED BY MEMBER @Inquisitor

you can also google: california toyota dealer refuses to sell used prius taken in trade, sues toyota motor corp.

irc, some have said changing the brake fluid might help

 

Since that person was a Gen 2 owner, there wasn't much choice: the Gen 2 'actuator' includes the accumulator and pump.

As you have a Gen 3, you face an additional question that the Gen 2 owner did not: do you need the accumulator/pump (one assembly), or do you need the actuator (the other assembly)? You see why the Gen 2 owner's post doesn't help you there. And both parts are kind of pricey, and both parts are kind of a pain to replace, so if one of them has a problem, you've got a strong incentive to figure out which one.

To make it that much more of a challenge, either one can go bad in ways that would give you similar symptoms.

I don't remember that you've described yet the exact sound you're hearing. If it is a frequent pumping sound, the cause can be either in the accumulator/pump assembly, or in the actuator assembly. In case I am guessing about the sound you hear, it would help if you could describe it better.

 

There is a service bulletin style instruction by Toyota, is that for the part OP needs to replace? I believe it's for the accumulator?

 

try changing the brake fluid

 

There are two sounds in that video. The kind of irregular quacking/honking sound that is heard throughout the eight seconds would be valves inside the actuator that are needing to repeatedly open and admit more pressurized brake fluid, because pressure is not being held (some one of the release valves may not be closing completely, so pressure is bleeding off, which the computer notices and has to keep wiggling one of the hold valves to admit more fluid and keep the pressure up).

In the last few seconds of the video, there is another sound, more like an urbane and polished rattlesnake. That is the sound of the electric pump having to run to replenish the pressurized fluid in the accumulator, because the actuator has been using it up that whole time.

If your sounds really are exactly like in that video, that pump sounded pretty good really. It's the valves in the actuator that are probably shot.

Because that video was Gen 2, they replaced the pump too because it's all one assembly in Gen 2. For a Gen 3, if that's really what it's doing, I would be tempted to leave the pump/accumulator assembly alone and replace the actuator.

Using the data list in Techstream, you would probably be able to catch what it's doing on screen.

 

I'm pretty sure you would need to use the techstream method of bleeding. You'd need to acquire a bootleg copy and install on a laptop, preferably with older windows OS installed? @ChapmanF can explain better. I can post Repair Manual excerpt in a bit.

 

Yes, that assembly.

There might be a possibility that having changed the brake fluid earlier could have postponed this day. I'm not sure I would bet much that changing it now would turn back time.

If you could reach the stars, though....

 

Brake bleed with/without techstream: