Brake accumulator pump (whirring): how much is too much?

Since there isn't a reliable vacuum source, periodic functioning of the brake accumulator pump is the only way the power assist braking can work. Maybe you are just listening for it now and hear it more often. On my car it runs about every third use of the brake pedal. And always when opening the driver side door. The longer it sits between uses the longer that pump will run when you open the door, so there is some leak-down (pressure loss) with time. There could be a problem if it seems to be running "more than usual", whatever that might mean. Don't know if it will throw a code.

 

I'm having the same issue... mine activates pretty much every 5-10 seconds no matter what I'm doing, and it is LOUD.

Here's a vid to show:

I also get chirping and creaking sounds when I apply the brakes.

Are my brakes about to completely fail, or am I just gonna have to deal with this?

 

Bring it to the dealer, maybe they'll fix it for free

SM-N900P ?

 

OP, that definitely is abnormal behavior of the accumulator pump.

The brake accumulator/booster on our 2011 is making some noises when hard brake pressure is applied, and also when almost at a full stop, then further pressure is applied to the brake pedal. Sounds like groaning/low frequency honking sound.

 

If your Prius is 2G, the brake actuator pump is covered under extended warranty to at least Dec 2017. My daughter's 2007 (102K miles) recently had similar symptoms as you described, the skid control ECU had logged a fault code, and no warning lights were on. I took the car to the local Toyota dealer svc dept and my findings were confirmed, so the actuator pump was replaced at no charge.

 

Brake fluid level will gradually move down, as pads wear. Having said that, there's likely not that much pad wear yet. But bottom line: brake fluid normally does NOT need to be topped up.

I'm not sure about "doesn't seem to be part of the 2010 brake recall": did you check with the dealership?

 

Bleed the brakes. Over time the ABS actuator uses a diaphragm that is actuated with a nitrogen cylinder. Eventually, it will leach nitrogen into the brake lines. This is why the increased pump frequency goes along with the barking sound (nitrogen bubbles). The pressure in the lines is not enough and the actuator pump must activate more frequently. Bleed the brakes before the actuator pump fails and it needs replacing. If you bleed the brakes and the barking and increased pump frequency return quickly, like a few weeks, the diaphragm is worn and leaking too much nitrogen and needs to be replaced with a properly working actuator.

 

Is that a big ticket item, or? We had this recall, I'm not sure exactly what it entailed:

 

Pretty sure it's a four-figure ticket. It's good to keep the differences between generations straight though. This thread started out with a Gen 3 question; Micheal Reeves posted a Gen 2 answer about the "actuator".

For Gen 2, that's ok, as the pump/accumulator and actuator are combined in a single unit anyway, so yes, in a Gen 2, if your accumulator goes bad, you can fix it by replacing your actuator. (And if you've a date in Constantinople, she's waiting in Istanbul.)

In a Gen 3, the pump-and-accumulator are a thing, and the actuator-and-master-cylinder are a different thing, so there's a greater importance on being sure which one you're buying.

-Chap

 

I'm just wondering if you have seen bleeding the system fix this issue? I have a 2007 with 188k miles. pump is running more than it used to but no codes or MIL yet.

 

I just had my actuator changed at the dealer, they told me the repair was $4500 retail, billed Toyota at the warranty rate at $3500.

The initial bleeding worked for about a month, then barking returned. So once it starts barking, prepare your wallet for a big hit

 

thanks for the info, selling the car as my wife just got a 2016 VW GTI to replace it (slightly worse gas mileage ). Just trying to be honest with potential buyers. Carmax only offered me $1600 for the car, but i would feel better selling to them than to an individual.

 

There is no disclosure needed as the pump on your car is working properly. If there's a problem with it, the car would light up the dash with warning lights.

I think you can easily get $3000 for the car if you list it for sale. Start at $3500-$4000 and settle with whoever offers you $3000+. I bet it'll sell in 1 day or less

 

This thread is in the Gen 3 forum. The last few posts look to involve Gen 2, but anyway:

If you have an early Gen 3 and it makes bark/honk/quack brake noises, don't forget there was T-SB-0363-10. Check the brake ECU firmware in Techstream and if it isn't at least version F152647108 (if you have 15" wheels) or F152647128 (if you have 17"), try getting it reflashed to that version or later before you start thinking about piggy banks and wrenches.

-Chap

 

I have some good news. I sent a letter to Toyota corporate, and with all the complaints they’ve been receiving, they decided to update the Toyota Safety Bulliten to include the additional Prius’ that weren’t previously covered in the C1391 or brake issue. So my $4500 repair bill ended up being $0! I suggest everyone to take their Prius to Toyota if they hadn’t been covered before, you will now. Cheers!

 

wow, thank you!

 

Do you mean they still covered the C1391 issue after the enhanced warrenty expires. Otherwise did you make the repairs after Decemeber 2017 and Toyota still covered the bill?