New guy here! I'm having brake issues and need help.

@ChapmanF is one member that's pretty conversant in this stuff. My mentioning his name will give him an alert.

 

Or @JC91006, @edthefox5 , @Patrick Wong ?

 

I received Customer Support Program ZJB a couple of days ago.

It doesn't list the DTC needed for this warranty work. "Coverage applies to the brake booster and brake booster pump assemblies. If the condition is verified the vehicle will be repaired with a new brake booster and brake booster pump assemblies under the terms of this Customer Support Program."

"The primary coverage will be offered until November 30, 2019 regardless of mileage. Secondary coverage is applicable for 10 years from the date of first use or 150000 miles whichever comes first."

Either call Toyota 1-888-270-9371 or the dealer to confirm ZJB applies to your car. If so, take it to the dealer. There is a mechanism to recover the cost of prior repairs as well.

 

Who did the repairs on your car? The Gen 3 cars have both an accumulator pump and actuator pump for the brakes. Sometimes mechanics that are not too familiar with the Prius may confuse the two items. So you should make sure the correct part was replaced by the mechanic

 

Somehow I though OP had 2nd gen, need more coffee.

 

The codes are telling you the same thing your ears are: pressure isn't being held in the accumulator, and the pump has to keep cycling to pump it back up.

A leak can be external (fluid escaping the system somewhere) or internal (some valve in the hydraulic system isn't closing completely, fluid is just returning back to the reservoir in the usual way).

If yours is leaking so constantly and so fast that you hear the hiss, and the pump has to cycle every several seconds, I'm guessing you don't have an external leak. You'd have a lake of brake fluid under the car by now if you did. So you have an internal leak; a valve somewhere is letting the pumped-up fluid hiss right back to the reservoir.

You've got a Gen 3, so there are parts of this story in two different assemblies. The accumulator assembly has the pump itself, and the pressure vessel that stores the fluid, and one relief valve. That is one place the hissing could be happening. On the other hand, all the rest of the valves in the system (about a dozen) are in the other, ac·tu·a·tor assembly.

Although those are two separate parts, you have to remember they're an interconnected system in practice. It can easily be one of the valves in the ac·tu·a·tor that is really where the fluid is leaking when the ac·cum·u·la·tor isn't holding pressure.

Sometimes the one-liner "fortune cookies" you can pull up for the trouble codes are no help there. If a mechanic reads a code that fortunes out as "abnormal leak in accumulator", he might just buy an accumulator and swap it in, instead of stopping to think, wait a minute, the ac·cum·u·la·tor pressure being lost could still be due to a problem in the ac·tu·a·tor, so I'd better figure out which it is before I buy one and swap it.

That's what I would guess happened here.

Since yours is leaking fast enough that you can hear a hiss, I bet you'd be able to touch your accumulator and your actuator with the end of a mechanic's stethoscope and find the culprit in one step.

Under support campaign ZJB, you might be able to get the actuator swapped at no charge at the dealer (and maybe even reimbursement for the already-swapped accumulator, if you paid for that).

-Chap