Gen 3 Known Brake Problem - outside of the ZJB program terms

If you are out of warranty, Toyota will tell you to go pound sand. Once they offer an extended warranty coverage campaign, they no longer do any good will repairs for the same item. Out of pocket cost for parts is about $1500, plus labor

 

Try this reset and see if it lessens it.

 

For me in western Canada, through Amayama, which usually is quite competitive on cost:

BRAKE BOOSTER ASSY, W/MASTER CYLINDER (upper unit)
Part no: 47050-47300*
Summary page: Brake master cylinder for Toyota Prius XW30, 3 generation, restyling 12.2011 - 11.2015 - Toyota Car and Auto Spare Parts - Genuine Online Car Parts Catalogue - Amayama
Part page: Buy Genuine Toyota 4705047300 (47050-47300) Brake Booster Assy, W/master Cylinder for Toyota Prius. Prices, fast shipping, photos, weight - Amayama
Cost for me, in CDN funds: $1995.68 plus $77.89 shipping

PUMP ASSY, BRAKE BOOSTER (lower unit, body resembles 2 side-by-side beer cans)
Part no: 47070-47060
Summary page: Brake tube & clamp for Toyota Prius XW30, 3 generation, restyling 12.2011 - 11.2015 - Toyota Car and Auto Spare Parts - Genuine Online Car Parts Catalogue - Amayama
Part page: Buy Genuine Toyota 4707047060 (47070-47060) Pump Assy, Brake Booster. Prices, fast shipping, photos, weight - Amayama
Cost for me, in CDN funds: $836.98 plus $59.55 shipping

Tally:



The first (upper) unit is the expensive one; what are the odds it's NOT the problem, can be left alone?

* There are a SLEW of part numbers for this item. I picked the last in the list, with the highest number, and also among the cheaper ones. Hopefully compatible.

 

The one that goes bad in the Gen 2 is the thing that looks like beer cans or a beer can standing up and a beer can laying down or however you look at it. The master cylinder looks like a regular master cylinder attached directly to the firewall with no normal round booster that's just the thing that pumps the fluid to the pump and the accumulator I believe I would think like most master cylinders on most of my Corollas they rarely go bad and then on the Corolla I don't own one with the ABS and the pumps like we have on the Prius thank goodness I guess.

 

Yeah, this is a Gen 3 thread. In Gen 3, the actuator is combined with the booster and master cylinder, and the pump/accumulator (beer cans) is separate.



In Gen 2, the actuator is combined with the pump/accumulator (beer cans are right on it), there's no booster, and the master cylinder is separate.

vvv Gen 2 Gen 2 Gen 2 vvv



^^^ Gen 2 Gen 2 Gen 2 ^^^

Gen 1 was the one with one beer can standing up and one laying down. In Gen 1 the pump/accumulator, the actuator, and the master cylinder were all separate things, and the master cylinder included a booster.

vvv Gen 1 Gen 1 Gen 1 vvv

^^^ Gen 1 Gen 1 Gen 1 ^^^

 

Is it usually the beer cans failing, the other bit ok? That would save some bucks.

 

In a Gen 3, if the pump ends up cycling repeatedly even when you are not using the brake, that tends to indicate an internal fluid leak, maybe through a sticky valve. It's worth pinning down which unit the leak is in, for each individual case before spending money, but the majority of the valves are to be found in the master cylinder/booster/actuator assembly (the one on the top in the picture above).

 

I believe to get to the bottom unit, the top unit has to come off. So if both comes off, you might just bite the bullet and replace them both at the same time.

 

Yeah except that's one expensive bullet (~$1600 USD delivered).

 

I was looking this part up for 2010, it shows 2 parts

brake master cylinder 47050-47140 - around $600 and master cylinder assemby 47050-47150 also around $600

Can't pull up 47050-47300 that you listed

 

Usually (but not always) Amayama's pretty good prices. Apparently very steep in this instance. There's 1/2 dozen part numbers here, and the 47140 one absent:

Brake master cylinder for Toyota Prius XW30, 3 generation, restyling 12.2011 - 11.2015 - Toyota Car and Auto Spare Parts - Genuine Online Car Parts Catalogue - Amayama

 

From what I can gather, both the top and bottom unit are around $600 each on discounted Toyota Websites. Expensive units to replace but if you plan to keep your car, you should buy them when you can. I'm waiting for the day Toyota decides not to offer these OEM part and then you'll be left with remanufactured options.

Better yet, replace yours before it fails and you can sell the used parts for a good chunk of change to lessen your overall cost of the eventual failure of this part

 

It is quite feasible if you have access to the repair manual. You will need Techstream once the installation is complete to bleed the brakes and a perform a couple of other initialization procedures.

The procedure also calls for flashing the ABS assembly with new firmware, which some users (justifiably) do not trust their mini-VCI cables with. However, if you buy your parts new, the assembly will come factory-flashed with the latest firmware so you can skip that step entirely and avoid buying an expensive cable.

 

If I remember right, the original repair-manual procedure for replacing the bottom unit was to work from below, after removing the suspension/steering subframe.

But they had a recall on some 2010s, where they looked at the prospect of doing that 80,000 times, and came up with a way of replacing that unit from the top, and I think without removing the actuator.

It involved some very one-off special tools. There's a thread here somewhere with a 3D-printer file that somebody designed for one of the tools.

 

Here's the pdf for the workaround: