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Toyota Prius - ABS Brake Modulator Valve - (44500-47141)

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Rick 432, Oct 18, 2023.

  1. Rick 432

    Rick 432 Junior Member

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    Good day,
    A few months ago, with the help of many on this site, I changed my abs brake modulator valve with a brand new Toyota part. Recently I have noticed the modulator valve activating sometimes when I stop or after I have parked the car (chattering). It is not the loud chattering I heard before with the original ABS modulator however I know it is the valve activating. The first few months after I installed the new part, there was not even a sound when I put my foot on the brake when I started the car but now there is the chatter for about 1 second. As I still consider myself a new Prius owner, I am not sure of all the different sounds etc on a Prius. My questions is, when a brand new ABS modulator is installed, is this chattering something to be expected after a few months after install? Do people who own a Prius all have this ABS activity?
    Again, thanks in advance.
    Rick
     
  2. Tombukt2

    Tombukt2 Senior Member

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    There's ABS activity all the time practically open the door step on the break push the power button any of that and you've got the noise apparently it looks like there's another pump over on the passenger side of the car on the fire wallet silver has a power connector going to it takes fluid from metal lines and feeds it to a metal block it looks like I haven't had time to look in the book to see exactly what it is but I have heard mine over there on the right side of the car start making a real loud hammering noise lately but I know why and it's not related to what you did I don't think but mine is hammering it makes a distinct louder noise than the original wearing clicking of the ABS actuator accumulator and pump that you replaced the $1,700 thing this other pump is on the opposite side of the car almost in line with the corner of the valve cover the back corner you'll look down and see it when mine activates it hammers almost like a radiator and an old New England home but mine is doing that I believe due to a defective ABS accumulator pump. So maybe sit in the car and make sure of the noise you're hearing and where it's coming from The pump on the right side or whatever that is over there makes a lot different noise and you can tell it's coming from the right side The ABS accumulator and pump is straight ahead in front of you when you're sitting in the car so you should easily be able to tell the two sounds apart Make sure you have that going on or not A mechanic stethoscope is good or some people use a long screwdriver and listen to the handle.
     
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  3. Rick 432

    Rick 432 Junior Member

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    I will review the noise and its location. I am most certain it is the ABS pump making the noise. It is not loud or thumping but more like a chattering sound. When I initially put my foot on the brake before I start the car I hear a short burst of the chattering which I did not hear until recently. I will also hear the chattering occasionally when I stop or when I am driving. I am not sure if this chattering noise is something common on all generation 2 models. I know it wasn't there after I installed the new pump. Ps. I have put about 2500 miles on the car since the new ABS was installed in June.
     
  4. Tombukt2

    Tombukt2 Senior Member

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    Well to be honest most of my cars get ones out of other cars because I'm cheap and I'm not spending $1,700 a pop for these things not as fast as the cars fall out of the sky. But I swapped the one out in my '09 and it makes no noise I barely hear it running when I shut the car off and the brakes are great it's bled well working fantastic. I changed one in another car the other day from a real old junk car and it didn't work It won't set that sensor steering angle sensor whatever it is and it won't bleed right so I've got to round up another one for that car.
     
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  5. Tombukt2

    Tombukt2 Senior Member

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    Well to be honest most of my cars get ones out of other cars because I'm cheap and I'm not spending $1,700 a pop for these things not as fast as the cars fall out of the sky. But recently in one of the other cars when I changed one of these things with a used when it didn't work and then I noticed I had this other little pump on the right side of the car making quite a bit of racket trying to keep up with the other pump or I don't know how it all works but I'm sure when I get to accumulator actuator on that car straightened out with another one the other pump will stop doing that or something like that
     
  6. Rick 432

    Rick 432 Junior Member

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    My feeling was if I purchased a new part that would be the end of it. From June to September, I did not hear anything from that pump after I installed it. Now I hear it occasionally and when I put my foot on the brake pedal when I start the car. The noise seems to becoming more frequent. It is a buzzing or rattling sound. I am sure most who have a Prius know the sound. I am trying to get a consensus from Prius owners that this sound is considered a somewhat normal part of owning a Prius. In retrospect, I wish I just left the old one in. It made a loud rattling sound every 7 seconds but it worked.
     
  7. Tombukt2

    Tombukt2 Senior Member

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    That's interesting I haven't seen a brand new one go bad yet but I've only installed like three but I'm in communication with the people that have those three cars. Generally I would think if I spent $1,700 on the part I would be done right for the next 10 years also. I do know the sound you're talking about if you know it's coming from right in front of you and that it's that thing only then it's that thing only and there you go take it over to the Toyota dealer have the parts guy come out and take a look and file a warranty claim I don't know how long you have I have a dealer account with Toyota they don't usually give me too much guff.
     
  8. Skystar

    Skystar New Member

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    I had what I thought was my actuator pump gradually fail with a pumping sound that finally went into a full cacophany of rhthmic oud irritation, there is a fuse you can pull see Youtube that can disengange a failing pump, losing some braking responsiveness, but apparently there is a secondary failing & knocking and a second fuse can be pulled ( Quiet ) finally, it will drive like a pre-ABS Truck, but care and pressure will be needed on the brake at Stop Signs, Lights - takes longer to glide to a stop. I have watched the actuator ABS Assembly go from $500 - $1,800 ( dealer ) ( online drops it to $1186 new apx). Robbery. I also heard a secondary noise - and fear when one expensive part is replaced ( also on Youtube a very challenging job- because it is so far inside the car) another will fail. If you are on your 2nd Lithium battery and want to keep "saving gas," be prepared. I saw a class action on these pumps that was won, but the damages were only to be paid until 2017 - I don't know why I wasn't aware of that back then, but some say once a Class Action, always a Class Action - I will be looking into it, and searching for tested parts with some guarantee. Good luck. The sounds will get worse - 1-5 years, kaput.
     
  9. Tombukt2

    Tombukt2 Senior Member

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    Look ABS pumps when they started coming out in the early '80s on the big cars like BMWs and all of that kind of nonsense some of the Cadillac Northstar iterations those modules and pumps were thousands of dollars and for some of those cars they still are I remember when our actuator for the generation 2 was about 575 but nobody was talking about it it wasn't a part that had a problem that anybody knew about etc etc hell the cars were still pretty new so something electrically just goes funky and that's that that's what electronics do. So now you can either buy the part or you can disable stuff and have different breaking and as long as it's you driving the car and you're aware of this and you're not one of those who's going to do something crazy because you forgot because you can. Well then you're probably an okay shape Make sure no one else drives the car I've done this many times in quite a few of these generation 2 Prius. Eventually you'll find a good used one A lot of these cars are going to come to the junkyard shortly with replaced actuators and now the battery's gone and people say ah that's it. Off it goes. And the break actuator is not a bad job You need a 10 mm brake line wrench It's a good idea a 12 mm or 10 mm all can be 1/4-in drive You need a long extension to undo the bolts where the actuator bracket is held on the firewall and you'll be undoing the inverter and twisting it around and hanging it over the front radiator core support reasonably not too bad of a job and know you won't mess anything else up just take your time disassemble what you need there are videos it's not really bad
     
  10. ChapmanF

    ChapmanF Senior Member

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    The pump sounds like a little rattlesnake, or a joy buzzer. The pump is there on purpose, and sometimes it does run. That's what it's for. 1 second when you get in the car is great.

    It's only a problem when it has to run crazy often or crazy long.