Finished replacing booster/accumulator. Brake Bleed Next

47070-47060 is the Brake Booster Pump Assembly with Accumulator for my VIN



That's a lot of years. If I'm searching the website correctly, it seems like this might be the only part. I'm not seeing other parts on autoparts.toyota.com that come up for "Prius Booster" or "Prius Accumulator" that look at all similar.

 

I am regretting buying used parts. It was so long between I ordered them and when I installed them that I didn't even remember what I had. Right now, I would have to save up probably until May to buy any new parts, or maybe get a small loan from a family member. The best I can do is the parts I have at the moment.

So, what I did was I reinstalled the old possibly bad "master cylinder / actuator" that is the correct part and hope it was the old booster that was bad, and I'm going to hope the "new to me" booster from 2010 is not part of the defective manufacturing batch.

I will probably attempt a brake bleed and calibration tomorrow and hope for the best. When the brake pedal is held down right now, the brake makes the boosty noise constantly which seems a little weird, but I recall that when I reset memory on techstream, prior to starting the bleed operation itself with the "new to me" wrong master cylinder it also made a continuous noise. So I don't know if it's a sign of a bad part or just a sign that it needs calibration or something.

Hoping for the best tomorrow. If not, I guess I'm going to move the Prius to the side of the yard and put the battery on the charger, save up for new parts, and try again probably in May or so.

Mystery solved. While I recently concluded that the wrong part was the cause, I actually now believe it is just the process of changing the actuator that can easily disturb the sensor bracket. (It wouldn't touch in post #8 and I bent to touch in #13).

When I installed the old master cylinder / actuator again, and I was trying to insert the retaining pin to link the push rod to the brake pedal, this time I was working from a different angle and I observed the brake pedal jamming into the sensor mount and bending it, and it really bent it way out of reach just like last time and I had to bend it back again with pliers. So, the bottom line is that when replacing the actuator, you either have to be really careful to move the sensor out of the way or watch the brake pedal position, or prepare to bend it back when you're done. Working with a mirror makes it almost impossible not to bend the sheet metal on accident, but if you push the seat back and lie on your back to install the pin you can easily see the entire assembly.

 

Definitely a whirring/joybuzzer kind of noise

 

So with the old actuator I completed the brake bleed, sorta. When it had me bleed front left a second time, some fluid came out that had no bubbles, but then it seemed no more fluid came out of front left.

Everything else seemed to bleed normally.

But when it ran the calibration at the end I was stuck with this that I couldn't clear:


This was with the brake bleed utility.

Then I did the ECB utility to do a linear valve offset again... which caused a second code.


Messing around with it, I got the C1368 to go out after messing with things... forget what I did exactly. Reset memory, Testing mode for yaw sensor calibration (it says 2 seconds or as specified in service manual.... seems to make noise forever), and redoing ECB linear valve offset.

But C1345 was still stubborn, ran another linear valve offset and C1368 came back.

On the dash I have the traction control light solid on, the BRAKE letters solid on with no brake depressed, and the ABS and the brake warning light all solid on

(Traction control light on left not shown).

 

I did signal check and C1368 went away. C 1345 remains

 

Because the front left didn't seem to bleed right last time, I reset the memory and bled the brakes again. I actually got some nasty looking brake fluid out of the system and the front left bled great this time.

After the linear offset calibration it says the brake warning light is supposed to flash quickly. Mine went from flashing during the offset (slowly? I do not know) to flashing not at all (solid on) indicating a possible failure for linear valve offset calibration?

After bleeding I ran the test for the yaw sensor calibration and I ran the sensor calibration thing which again made C1368 go away.

C1345 and all the dash brake problem lights remain lit.

I'll probably try driving the car and see if it "seems" normal. If it's just ABS and traction control that don't work, I don't really care about those things. But I'll see if the braking itself seems spongy or the regen has issues.

I'm afraid I might not have much other options but to try and buy the master cylinder / actuator part otherwise and see what happens in a few months.

Scouring prius chat and the web some folks indicated maybe C1345 could go away if I unplugged the battery for a long while. I do not know, maybe I can try that too. But I'm not optimistic.

When I hit the magnifier on the C1345 I get DTC S305-12 malfunction is present.

 

Good question. The car had an unknown history before I got it. It was the first time the brake fluid was replaced by me. Car has around 200K miles on it.

 

Looking at that manual the only thing I can think is maybe the temperature of the actuator got high from pumping the brakes a lot during the bleed process?

I would be interested to see what is under the "info" for this section right here though to see if I am missing something on this part:

 

A lot of it is overly vague. Like, how can I know if my actuator is too hot? The manual does not describe any method to know if it is too hot or not.

Seems like manual or no manual, we're left with the guess and check method, or hoping someone else has an experience to share of their own trials and tribulations.

My gut feeling is that the part is bad.

 

So, everything is reassembled, and I took it on a test drive. The brakes seem to be working, although I still have brake warning, traction control, ABS and BRAKE lit up on the dash.

If my only error code in the C1345 and there are no codes anymore for loss of pressure or anything, and the system isn't doing that constant dying whirr noise, maybe the brakes more or less work.

Before when I had not used the car in a really long time, the brake trouble lights on the dash magically turned themselves off then turned themselves on again after several minutes of driving.

I'm kind of hoping that might happen again. I'm going to let the car sit for like 2-2.5 weeks straight at least in April, and probably disconnect the battery from the terminal if I can remember to. Maybe when I get back everything will magically work.

In the meanwhile I'm going to monitor the mpg to see if it seems like brake regen is working properly, and if it seems like come May, when I have funds, if things are still not good I guess the only answer will be to replace the actuator again.

 

I had a nail in my tire I had to patch. Did that today and then did an extended road test.



This is the max regen CHG I'm getting in D mode when letting off the accelerator. I'm getting like double the CHG in B mode. Applying the brakes doesn't visibly increase the CHG.

Further, I'm only getting ~35 mpg. This leads me to believe that I am getting no additional regen by depressing my pedal, likely as a result of the inability of my actuator to calibrate.

It sucks, but my car at least isn't deadlined for now. Probably I'll have to drive it as it is for a few weeks, then I can get the new actuator and I pray replacing the actuator will solve my C1345 code and bring my regen back.

Between more or less giving my Gen 2 prius to my friend like 10 months ago and this car being deadlined for like 6 months I forget how the brakes are suppose to feel, as I've mainly been driving a pure ICE-mobile for the last 6 months. Nevertheless, the car stops when I tell it to stop, and I've tried slamming the brakes at high speed and she stops fast enough that I'm satisfied in the safety factor. I feel like the accumulator fix is overall making the brakes function.

Applying the electrical tape to the dash to cover the brake warning light also helps... on a pyschological level.