Brake + ABS + Cabin Alarm > no brakes =(

Please post the codes from the brake computer so we have some idea where to start.

If you don't have something like mini-VCI/Techstream, or a dealer nearby to pull the codes for you, just fit a wire jumper between the Tc and CG pins in the diagnostic connector (over the driver's left knee, assuming it's a left-drive car), and count the blinks of the ABS light. (You can find several other threads on this forum where that's described in more detail.)

Sorry about that disconcerting experience!

-Chap

 

I hope he's right, but something doesn't add up. You described your pedal as spongy and sinking down. Loss of the boost pressure (assuming no other coincident problem) makes the pedal high and hard.

-Chap

ps. there isn't really programming to do. A bit of bleeding, which is easier with Techstream, but only involves actuating one solenoid so it shouldn't be impossible for mortals. Got trickier in Gen 2.

 

Hey, didn't this mechanic say he "took everything out and tested it"? How much did he charge for that? Billing by the hour is the only way to afford that method of finding problems....

Also, if he had a bunch of stuff apart and put it back together (without replacing the problem part? he wants to do that labor twice?), then maybe you don't need to worry as much about what can go wrong in doing all that work, because some of it probably already has. It's not even clear that the problem you have now is the same one you had in post #1.

Are you saying it was spongy and low in post #1, but since this mechanic looked it it, it's high and hard?

As for replacing the pump, contributor rlin78 recently showed that it's a challenging but not impossible job, and can even be done without evacuating the air conditioner.

-Chap

 

My cars going through this right now took it to 2 mechanics who both said it was the ABS motor/assembly. Same prices, same sinking pedal. Good luck! let me know if youre able to do yours I might try mine. I found a part (refab maybe? I m not sure ) for $110 with a 1 year warranty: [email protected].

 

It's most likely a part from a wreck vehicle. That's no a bad price for the pump, 1 year warranty seems very generous, you want to make sure the part number is 47070-47020. It's about $1500 new from Toyota.

In order to correctly diagnose the problem you will the codes from your mechanic and use the factory service manual procedure to isolate the faulty part. Mine was a pump failure which I fixed with Chap's help last month and it is still going strong. See our discussion here. I wouldn't say it was easy, but it's within the ability of a home mechanic even without any powered tools. You will need Mini VCI or other Prius aware scanner to bleed the system properly. I am not sure what caused the sinking pedal because the pump failure would cause the pedal to become hard to push. Think of the pump is like your vacuum brake booster in a conventional car. The sinking pedal might indicate other issues. Mine did have a small leak over the pump for the last 7 years before the pump failure, I just topped it off every so often until the pump completely failed. So I shouldn't say I was surprised by the pump failure. Good luck as well and let us know what you end up doing.

 

Nice video, the annoying buzzer reminded me what I had to put up with for a few nights. It's possible that you have a bad accumulator. It may be worth your effort to just replace the accumulator, I tried to loosen the accumulator, but I didn't have a vise and it didn't budge at all.

If you don't have a scanner, you can use a thin electrical wire to connect the Ts and CG terminals on the DLC3 (ODB II connector) and read the trouble code. You will also need the factory service manual (FSM) before you can proceed. Again, this is not something I would recommend attempting without the FSM or Prius aware scanner that can bleed the brake properly. Also, be prepare to give yourself plenty of time for the repair. You need to get the codes, find out if it's the booster pump, learn how to take it apart, put it back in, bleed the system and hope that you got the right fault part. The booster pump seems like a high failure item for first gen Prius, I just hope the prices don't go up for the pump as first gen Prius become more rare.

This is a diagram from the FSM showing you how to short the Ts and CG terminals. But you need more than just this diagram, you need to read and understand how to replace the booster pump.

 

My notes have that you get the trouble codes out by connecting Tc to CG. (Tc is also shown in that diagram.) Ts to CG is used for other purposes, like testing the wheel sensor signals.

Tc to CG is the basic magic jumper trick that makes all the ECUs (except battery and HV) blink out their troubles on the dash.

-Chap

 

Chap,

you are right, I went back and double checked, it was Tc to CG, not Ts to CG as my original post. But no harm done if you connect Ts to CG first, you just wouldn't get the codes.

 

You have to make that decision yourself. It sounds like you either have a small leak or the pump/accumulator is failing causing brake pressure to be lost. With a used pump/accumulator that you bought, you are taking a gamble. So the question is whether $560 is worth it to gamble fixing your brake. The labor is actually reasonable in my opinion because it took me way longer than 5.2 hours to replace the pump/accumulator. But if the shop has done it before with success, there's no reason why they can't finish it faster. Have you approached them about installing a used pump as some shops won't install used parts?

 

Glad that your car is operational again, but it is not clear why the air conditioning system has to be disturbed when the brake actuator is removed and replaced.