Brake Booster Malfunction

Going to bring this alive again.

2010 Prius I with 230,000 miles. Bought the 47050-47140 booster assembly and the 47070-47060 pump assembly. Going to attempt the installation myself but at a buddy's shop because of the supposed calibration that needs to be done. Hopefully it'll be soon. The C1391 code comes up almost every day, I clear it, and keep going. There is an audible leak inside the cab at the booster where the pushrod comes through.

I'll update later.

 

You should get the updated version of the brake booster. The sticker label is wrapped around the circular part instead of parallel to the cylinder. I am not sure if this problem is related to the regular brake fluid change or not. Because it is the air pump issue, not corrosion.

 

This is Toyota’s method of avoiding a part number revision I guess; not sure why they would take this approach. And you would pray they didn’t ONLY rotate the label. Or that some enterprising sellers haven’t managed to peal off labels and rotate…

 

Brake fluid pump, not air pump.

 

My guess would be something simple, like, they were sourcing accumulators from a couple different suppliers, who happened to apply the labels different ways. And later, when a bunch started failing early in the field, and they took those apart and realized it was because the bellows was made undersized and could bang around inside the can and crack, they said "oh look, these all came from supplier X, who put the label on this way, and that gives us an easy way to tell the technicians which ones to look out for."

 

I specifically asked the parts guy if this was the latest and greatest and he said yes.

I've got the parts here ready to go. I have Techstream on my laptop. I'll be starting the replacement in about 30 minutes.

 

Definitely not going as planned. The part replacement was the easy part. Now, I have. "Check hybrid system" and the techstream is saying it can't communicate with the brake ecu. So, i can't perform any functions. I had an issue with the brake light switch and now that's fine, but after that, it's been going nowhere.

The U0129 code is here saying lost communication with brake system control module.

Any insights? Did I miss something? I'm sure I did as everything I've seen hasn't gone this far in to the steps.

Help!

 

Which ECU is saying U0129, by the way?

You've double-checked the electrical connections to the new actuator?

 

Calm down, check all the connector first. If you are sure you installed everything properly, you can bring it to experience hybrid mechanics of dealership to trouble shoot it. They may know what to do although you may need to pay $100 for diagnostic fee

 

I'm guessing the Brake System Control ECU is the code. This morning I'm going to spray contact cleaner on things. There's only 3 plugs. Right? The pump runs so I know that's working. I had the batteries disconnected all night and the 12v on charge. I'll go to the garage here in a bit to start the day.

 

Brake system control. Pretty sure but I'll go back through it.

 

Nothing worked so far. I'm going to put the old booster in and see if it's perhaps a bad part.

 

Figured it out. All my fault. I'll explain later. *facepalm*

 

I didn't put my question clearly enough. Brake system control is what the U0129 code means ... as in, whatever ECU said "U0129" is saying "hey, I can't communicate with the brake system ECU."

But who is the "I" in that sentence? It takes two to not communicate, and the other party is whichever ECU is giving the U0129 code. I was asking which ECU gave the code.

If you're using Techstream, that's easy to see, because it lists all your codes grouped by which ECUs are giving them.

Some other scan tools make it harder.

 

It's all been through techstream. I found the cause. A fuse. I'll tell that (stupid) story in a little bit.

Working on bleeding now. Wasn't sure on steps so now I'm doing the "air bleed" as the "ABS Replacement" step was being weird.

The step for bleeding the stroke simulator doesn't seem to be working? I don't get anything out.

 

The other thing is that some times when it comes around to that, it'll enter to the stroke simulator then it makes a pop noise then gives the message that "air bleeding has failed". Then says refer to repair manual.

Something else I missed?

 

Ok. For this time, it doesn't look like there's any more information needed. And since you have Techstream, if there is ever another time you have a U code, and somebody asks you which ECU gave the U code, that is very easy to answer: on the screen where Techstream is showing the codes, they are grouped under which ECUs gave them.

 

Hi Christopher.
You mention a fuse. Can you be more specific?
I have also been battling the U0129 error on my 2010 prius.
We also replaced the brake booster. But still getting that pesky U0129 error from time to time.

Any help is appreciated.

 

Same thing just happened to my 2010 Prius and the 10 year ended 2020. So it will cost me $3K The car not worth $8K It only has 60K miles on it so maybe that's why it took 13 years to happen instead of 10.

 

Let me know if you get anywhere with this. My Prius 2010 is costing $3K to fix the BRK Master CYL and Brake Booster. The 10 year was up even though I have but 60K on the car.