Which to replace, master cylinder or pump?

No it's not the master cylinder leaking pressure You have to look at this a different way It is the accumulator which is a little storage tank that holds brake fluid under pretty intense pressure and then when you step on the brake the valves that open up in the brake actuator in my car whatever it's called in the generation 3 whatever when that is called for then the fluid moves under the pressure from the accumulator through the valves because you push the pedal and a bunch of other things go on to happen like the car stops or slows through four-wheel disc brakes in your case I believe the part that most technicians would bet on is the one that has all the electronics most of the plugs and all that sort of thing which might be a good bet but the other part can also be involved in the mix and now you're going to pay two times labor for some guy to say well I don't do that it's a waste of money yeah until I come along pay you to do the part with the accumulator on it don't do the other part you go to bleed the brakes or what have you and find out that in fact I do need the other part now I have to pay the labor over again possibly just depends on who you're dealing with so you need to source this out very well. A mechanic stethoscope will go a long way and knowing how to use it and getting the car in a quiet place where you can listen carefully but I don't know where the thread is I imagine it's here somewhere and I imagine it's on YouTube and quite a few videos I have seen the car guy the foreigner that does all the Toyota work has discussed this before too I do believe so there's plenty of information out there that you can probably use but for your individual situation the mechanic stethoscope and careful diagnostics and paying attention may yield you a decent outcome.

 

In gen 3 it's called the master cylinder. They changed how all the parts are combined into assemblies, so this one thing on top is all of (the booster, the master cylinder, the actuator, and the ECU) together, and it can be called all of those things.

The thing on the bottom is just the accumulator and the pump.



What you're used to in gen 2 is different; in gen 2 the accumulator and pump were combined with the actuator, but the master cylinder was separate.

 

Depending on how long you wait to replace it, if the master cylinder is leaking,
and the pump has to run and run and run to keep up, it will wear out the pump faster
To replace ONLY the master cylinder, and not the pump, is a short time you'll have
problems with the pump failing and try to blame the Toyota dealership for it.
That is one reason they will only replace as a pair. And my personal opinion is this is
the correct and smarted methode. Yes, it cost more, but if your brakes fail, and they will,
what will that cost you?
And, will either place do a correct dianoses and figure out WHERE the leak is? It may
just be the pump. But the situation is still the same.

But, depending on your finances... if you only have enough to do the master cylinder, that's what you do.
But it will cost even more if/when the pump goes out.

If they replace both, you have peace of mind. If either fails, they are responsible.

 

Hello! Have you succeeded in repairing your brakes system ? I replaced my booster pump/accumulator assembly because it was running every 13 seconds. Next I bled the master cylinder [m/c] using the bleeder valve on top of the m/c and then I bled all 4 wheel cylinders. Now I still have air in the m/c. I down loaded Toyota Techstream to my laptop. Now, were you able to bleed your m/c using Techstream ? My booster pump still seems to run too much.

 

I hope to learn how to bleed the master cylinder [m/c] using Techstream - soon ![/QUOTE]

 

Has your $26.99 thingie arrived yet, and have you looked in the CD and are you sure Techstream isn't there?

 

You must be a spry 80 year old to take on this job. Short of changing the head gasket, this is one of the more difficult jobs primarily due to access and secondarily due to the maze of brake lines, cables and associated devices.

Proper bleeding and calibrations require Techstream or other high end scanner.

2010 had a run of defective pumps as well as master cylinder replacements. As a result many pros want to go in once and get it right. The prices of the parts have come down once Toyota’s free replacement program expired for most gen3s.

Buying from Toyota is the only good option; some used suppliers will ship the wrong part number because they all look the same on gen3s but they differ by year, wheel size, hatchback vs v wagon etc.

Buying from an online Toyota dealer often gets you the mechanics price.


Notice this master cylinder is for a 2010 hatchback with 15” wheels.
Toyota 2010-2011 Toyota Prius Brake Master Cylinder 47050-47140 | Toyota Parts

The Pump Assembly is more generic, costs about the same and is Toyota 2010-2018 Toyota Pump Assembly, Brake Booster 47070-47060 | Toyota Parts

Always verify parts by supplying vin to dealer before purchase. Sometimes this can be done online.

 

The Chinese made hardwired Techstream interfaces (mini-vci) have been around for years and include a version of Techstream which has been hacked to operate without a Toyota subscription.

The supplied cd version of Techstream is usually older so the vendor instructs you to download the latest hacked version. Which may be necessary if your PC laptop does not have a cd reader.

Many people have problems installing it. It requires a registry hack which is manually initiated by an included utility. However the instructions are worse than poor so the vendor suggests you find some YouTube video for help.

Assuming you get it running, you are told “do not operate Techstream while online! It may break!” It may be disabled by Toyota since they did not authorize these guys. So many otherwise “honest” users install it on an old laptop with disabled internet.

Plus there is a learning curve to use Techstream and there are no user instructions provided. So it can be trial and error to install and use.

Finally one of the more elaborate uses is the Techstream Brake system bleeding and calibration. I think it would be easier all around to let a pro do this step even if it was $150.

If it came with a mechanic like their ad shows…



Instead you get these cautions



Amazon Reviews of the same Product



Or this if you are lucky



Your results may vary

 

If you can get it working it is really the same as legal versions except you can’t go online with it and do things like updating ecus or access the Toyota Information System for “live” procedures and schematics with hot links.

I have heard of people doing old school bleeding and limping into a dealer for the proper system level bleeding and calibrations. Some independent shops can do it as well especially those who have done hybrid brake master cylinders. It might be worth finding those guys before you dive in.

The separate software “keys” are just a guy hoping for easy money. Your first vendor will give you a hacked key for use in the hacked software.

Legitimate keys are sold by Toyota by subscription by the day, month or year. Shops or individuals would buy the Professional access to legitimately use Techstream. So if you buy two days from Toyota it works with online access for two days.



Website
https://techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&goto=https%3A%2F%2Ftechinfo.toyota.com%3A443%2Fagent%2Fcustom-login-response%3Fstate%3Dt4xGMuwqyxydX5AdZrfK5gQ6Vx8&original_request_url=https%3A%2F%2Ftechinfo.toyota.com%3A443%2F

 

Sometimes you have to chuck a piece of solid wire to a drill and push it through.

 

OVEN CLEANER!
Spray it in both ends and let it sit for a few minutes, then spray again.
It will eat the carbon. Since it's clogged, you'll have to spray it several times.
Let it sit for 30 minutes or so. Then use the pressuer washer to clean it out.

You may also have to us a bicycle spoke or welding rod to bore through it and
clear it out, at least to get it started.

Since it is so clogged, you may have to use the oven clean/pressure washer a few times.