Brake Booster is going out, brought it to mechanic.. does this seem right???

I have a 2010 JBL solar roof loaded car that's just started doing this and I'm going to start with the accumulator assembly apparently that house is all of the electronics that commands all the lights to come on for the most part then if it turns out that I have a hydraulic pumping issue from the pedal then I'll deal with the master cylinder or whatever they're calling that in this series of car usually from what I've experienced so far is something to do with that accumulator and pump assembly generally speaking so I'll hold off on the master cylinder that's just what sends some fluid over to the accumulator pump assembly and then all the computer start doing their thing and that's that.

 

On a 2011 I would change both. Some will say try the master cylinder alone but it is a lot of duplicated labor if you go in twice.

These are known to go bad. Toyota changed them free for about ten years. They started that program with only one part but quickly defaulted to both because of come backs. Many including my 2012 v went out in five to seven years rather than twelve like your case.

As a result it is very risky to go used since the remaining functionality of the used part could be short.

Some used buyers get the wrong part because there are different part number versions per year and per model. The only way to know compatibility for sure is to crosscheck part numbers obtained from a vin lookup of the donor car and yours. Several have changed master cylinders two or three times because of this alone.

I would go for the new master cylinder alone before going used.

 

Tombukt2 might be a bit mixed up about which parts of the brake system do what (or maybe I just can't tell what Tombukt2 is saying about it). Anyway, there are these two things:



Note that both things have 'booster' in the name, making them extra tricky to keep straight. The bottom one is the "booster pump" (never forget to say pump!) and combined with the accumulator, and that's the thing making the noise you hear.

More often than not, the reason it has to make that noise so often will turn out to be in the top thing (called booster in the picture, also sometimes called master cylinder and sometimes actuator, as it combines all those things) because there is much more action up there, around a dozen different little valves.

Sometimes you'll get a successful repair by just replacing the top thing. Sometimes you can use a mechanics' stethoscope and hear a hissing, leaking sound in one unit or the other in between the pump runs.

On the other hand, if it's been this way a while, making the pump run that often (normally it can go hours between, if the brake isn't used), that can have put a whole lot of extra wear on the pump and accumulator, even if the original problem was in the top thing. So that can be a consideration in favor of changing both.