Need advice for notorious Brake Booster issue Toyota refuses to cover

For my G3 Prius this is the best video I could find: Shows replacement of both Actuator & Pump.

Gen 3 Prius 2010-2015 Brake booster and actuator replacement for C1391 code

 

This is an interesting thread as it covers a few points I'm dealing with right now on a "new" 2014 Prius (currently at 50k miles). Call me crazy for picking up a used Gen3, but I really like the form factor, so just went with it. This is a newer car, which I don't have much "runtime/maintenance" feel for yet, but the booster runs longer in this car than the 2010/2013 I had prior. NOTE: in my 2010, I did have Toyota cover the brake booster replacement under the ZJB warranty. So I may have used up my only 1 life-line.

1. I would say the 2014 "boosts" about 5-8 seconds in the morning when I open the door. My two prior Prius seemed to run about 2-3 seconds max.

2. The other thing I found a bit odd: when I come to a very gradual stop in the 2014, and am waiting at the light, I have pushed harder on the brake pedal (after I have been stopped for a few seconds); and the booster (aka, duck honker) kicks in for a few seconds.

3. I have all the records for this car and there doesn't seem to be any sign of a brake fluid/flush in the 8-9 years of its life, which I find hard to believe. Most of the records are from Toyota dealers. I also have a brake fluid moisture sensor and it measures 0% moisture, indicating the fluid is probably at least moisture-free.

So a few questions for you all:

1. how long does your "normal" booster run in the morning?
2. if you come to a stop, and then press moderately hard on the brakes while stopped, does your booster kick in at all?
3. Having a 2014, is there any reason to believe I'm going to be immune to the brake booster failure, or are the part numbers the same in the 2014? I have the TSB/ZJB documents, and they suggest even 2015 models may have this issue.
4. I have about 11 months left on the 10-year ZJB warranty. if it does seem like the booster may be going, what can I do to really make it fail?
5. I don't have any DTC's right now using my iPhone-based scan tool (Car Scanner Pro). If I had Tech stream or something more advanced like that, would I be able to get more visibility into this problem?
6. If brake fluid is moisture-free with a tester, as measured in the reservoir, is there a reason to change it? In other words, perhaps water is more concentrated in the caliper location and causes problems there, but is undetectable in the reservoir?

 

Same, no, no, nothing and no.

 

1. how long does your "normal" booster run in the morning?

Answer: I just checked the 2010 & 2015 - both ran the pump for ~8 sec. when drivers door was opened.

2. if you come to a stop, and then press moderately hard on the brakes while stopped, does your booster kick in at all?

Answer: I have never noticed the booster pump run at all, while stopped at light with foot on brake. I have never tried pressing really hard on the petal while stopped so I don't know what would happen.

3. Having a 2014, is there any reason to believe I'm going to be immune to the brake booster failure, or are the part numbers the same in the 2014? I have the TSB/ZJB documents, and they suggest even 2015 models may have this issue.

Answer: I suspect all models will eventually fail. Changing the brake fluid every couple years could prolong the eventual failure. The brake actuator is very complicated internally with many places for a small internal leak to develop.

4. I have about 11 months left on the 10-year ZJB warranty. if it does seem like the booster may be going, what can I do to really make it fail?

Answer: I can see no way to force a failure. I myself knew the pump was cycling too often & took in to Toyota for a checkup. There were no codes set & Toyota said the system was functioning correctly.

5. I don't have any DTC's right now using my iPhone-based scan tool (Car Scanner Pro). If I had Tech stream or something more advanced like that, would I be able to get more visibility into this problem?

Answer: With this problem of an internal leak someplace, causing the pump to cycle too often, the pump cycle time while sitting with the Prius powered up is the best indicator of pending failure. The pump can cycle on every 10 seconds & the system will not set a code. When the cycle time gets to <5 seconds the dash lights up & you have a failure code in the ABS system. Toyota will not help you unless there is a code present.

 

My 2010 runs about 20 second from an overnight sitting when I open the drivers door.
After it shuts off, it will start and run for 2 or 3 seconds. After that, it runs for a few seconds
every 25-30 seconds. Depending on how often I have to use the brake peddle coming up to
and sitting at a stop like, it may or may not cycle.

It has done this since I purchased it in 2017, 202,000 miles ago. It will have 319,000 this week.

When I first starting reading about the issue with the brakes, I was "concerned" that mine was
going to be failing soon. That was early in 2018. Now I don't care.
it seems each car and model year it acts differently for the cycle times. Unless it is running all the time,
or cycles every few second, I wouldn't worry about it. When it does fail, the brake pedal will feel like
a non prius car that has lost vacumm to the brake booster, the pedal will feel hard to press and the
car won't slow/stop easily.

 

Since kc410's just replaced the ABS units that would be an excellent case for how the ABS unit should be behaving since new. Thanks KC410 for taking your time and answering the questions.
I had about 20+ seconds of the ABS booster pump run time every day morning when driver's door gets open.
And then I thought WHAT IF my 12V auxiliary battery is getting low? I put the battery on a charger, let it charge for 30 minutes or so and sure enough the booster pump run time shortened right away to about 7 seconds when I opened the door since a previous day. I might be looking for a new battery since mine is over 11 years old now. I also have the pump kicking for a few seconds often when coming to a complete stop at a traffic light. I have 2012 Prius with 165k miles.

 

Being inspired by this thread I have decided to do "ABS replaced" bleeding procedure on my 2012 Prius today. I got the wheels off anyway to change for winter, so why not?
This was done 1)to ensure that all internal ABS units components have the new brake fluid and 2) to check if my DIY scan tool could actually do this bleeding. I did not replace the ABS unit itself yet, as it is still working ok.
I have Thinkdiag Bluetooth 2-way scan tool that works with Android App. I just followed the attached page from the repair manual, except I used my scan tool instead of Toyota's Techstream and selected " ABS replaced" procedure instead of simpler "Air bleeding". It was easy once the car was on jacks, wheels off, and a whole cowl removed. Just followed instructions on the scan tool. These instructions on my tool were the same as I saw in videos with Techstream. Now if something goes wrong with the ABS actuator + pump & accumulator I know that I can order the parts and replace myself. Hope it helps others here.

 

10yr/150k coverage.

 

is the 12v okay?

 

You might have mentioned what trouble codes you have somewhere earlier in the thread, but I didn't look back far enough. Can you post what the codes are now, with your 6 dash lights on?

If you don't have a scan tool to read trouble codes, you can get them for the brake system this way:

https://priuschat.com/wiki/blink-a-k-a-flash-codes-how-to/

Trouble codes all have their own detection conditions, and a code that's gone away won't come back until its specific detection condition is next noticed by the car, which can be right away or not for a long while, depending on what the specific condition is.

So the "what does it mean that I didn't have this code for a day?" is not a completely useless game to play, but it is best played by looking up what the code was and what that code's detection condition is, and then asking the question about that.

 

I had maybe similar issue with intermittent ABS system and brake light coming up and go. In my case (as diagnosed by a local mechanic) it was due to rear wheel hub sensor failing. The mechanic said that trouble code was for a sensor having a debris. When any of the four wheel sensors starts to fail, then the whole ABS, stability, traction, braking lights will light up. After replacing the wheel hub assembly all went back to normal: regeneration was back and fuel economy improved. Looks like I had that issue hiding for a while as I had it happening from time to time.

I would recommend to first scan the trouble codes from ABS. I invested ~$70 in a scanner that can read live data from all vehicle systems, including each wheel sensor while driving. And after awhile I got similar situation while, as I found myself, the other rear wheel hub sensor was going bad. This time I saved money by just buying an OEM replacement hub and had local mechanic replace it.
Unfortunately, something is wrong with this website as I cannot upload the screen shot file anymore from the scanner, therefore I had to attach the scanner link where you can find my review of the scanner by looking for the reviews that have pictures. I bought the scanner with my own money, no affiliation of any sort.

Hope this helps.

 

That's why it's always recommended to replace BOTH hubs if one goes bad. Just like shocks
and struts....

 

C1391 indeed indicates the car is ready for some brake work.

 

thx for updating us. i agree that the car without the brake repair is worthless. what needs to happen is some lemon or recall issue needs to be mandated by the government so Toyota can be forced to fix this. but im not sure how all that legal work needs to proceed to actually qualify something as an official recall. Ill try to go onto the site and submit my feedback too. maybe we all need to start submitting complaints to NHTSA website??? then government will start doing something? My brakes are good still but im planning on keeping this car longer and sense it may develop the issue.

 

i'm not sure how many years the government is willing to force carmakers to provide free safety repairs

 

I just filed a complaint with NHTSA, even though my brakes are in working order. I asked them to force Toyota to extend the brake booster warranty to 20 years & 300k miles. the forms suggested that i file a complaint, if I had a problem, but i said in the verbiage that I don't yet have a problem but just want the government to take action. Maybe if enough people do this, we might get some sort traction (PUN intended!)

As a PSA side note, while filling out the forms, I noticed there was an option to receive notices. I checked yes to allow that, so I presume they may now have me and my VIN recorded and send my updates on any other issues with my model year Prius. Seems like a plus.

In general, I still think the Gen3 Prius is a great car and doesn't have a comparable equivalent in the new market today. each Prius is getting smaller with not much MPG improvement. So I'm committed to the Gen3 for the foreseeable future. I think Toyota could have a win if they just took the Gen3 body, enhanced the tech slightly and fixed these stupid issues like the brake booster, EGR clogging capacity, oil rings. the car would still sell like crazy IMO. Even Toyota doesn't have a good new comparable hatchback in their lineup. I don't want a sedan corolla, or camry. I also heard Toyota discontinued the Avalon Hyrbid/ICE, which also seems like a dumb idea, but maybe rich avalon buyers don't care about a few MPG. LOL!