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faint jack hammer sound from center of car

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Janice, Oct 13, 2010.

  1. Janice

    Janice New Member

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    I first noted a very faint jack hammer type sound from center of bottom of car last week-noticed it once or twice while driving, but then it continued, a little louder, and even continued when I turned the car off for about 5 minutes. Same thing happened when I drove to work the next day, and when I went to get in my car after work, it was still doing it-I think the noise must have lasted all day. Took it to the dealer and he heard it the night I dropped it off but nothing the next day when warranty inspector came out. The service guy did tell me he captured it on the computer read out and it had something to do with the brakes or ?ABS system. Service said they would drive car home and check it out-he got nothing on his long ride home but the next morning when the car was cold, it reproduced the problem. Inspector was due to come back out next day when car was cold, but came later when it had warmed up and did not reproduce, so will not fix it. They tell me is is safe to drive...is it?? And what the heck could this be?
     
    #1 Janice, Oct 13, 2010
  2. dogfriend

    dogfriend Human - Animal Hybrid

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    I believe that the faint jack hammer sound is the Brake Accumulator pump that is part of the Prius brake system. Under normal circumstances, it only runs for a short time infrequently to build pressure in the hydraulic brake lines. If it is running continuously, that is not normal.

    Do you have any paperwork from the dealer that noted the DTC(s) (error codes) when the tech scanned the computer? If you could post the code(s), it might help us to give more specific advise.
     
    #2 dogfriend, Oct 14, 2010
  3. Janice

    Janice New Member

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    Thank you so much-I will find out
     
    #3 Janice, Oct 14, 2010
  4. hill

    hill High Fiber Member

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    Your avatar shows your car is about 5 years old. Did you buy it used? You should have heard it for the entire 5 years if you've had it that long. You can reproduce the sound by simply pressing on the brake for a few seconds, release, and do it again. It doesn't hurt the car. Within a couple times, the accumulator will pump up again (making that sound), and you can verify that this is what you are hearing. . . . and welcome to PC!
    :welcome:

    .
     
    #4 hill, Oct 14, 2010
  5. tanglefoot

    tanglefoot Whee!

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    Sorry about the thread resurrection, but I think I just experienced it! Twice when I booted into ready mode yesterday, (about 20 deg. F) there was a not-at-all subtle jackhammering sound (steady, fast rhythm) coming from the undercarriage, somewhere toward the center or back of the car (no indicator lights illuminated). Not at all like the operation of the brake accumulator pump. It lasted a few seconds, and it didn't matter whether the car was moving or not, or in D, R or N or with or without the brake pedal depressed. Once rolling out of the parking lot, it stopped. Is there something under the car capable of making that kind of racket (ABS actuator?)? I'll have to see if it happens again.

    My Dad said he had a brief incidence of it once with his '07 while backing out of the garage. His did illuminate a brake light. The sound and light have not reoccurred for him.

    I'm not too worried about it---mostly curious.
     
    #5 tanglefoot, Jan 10, 2016
  6. valde3

    valde3 Senior Member

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    Has anybody read the fault codes from it?
     
    #6 valde3, Jan 20, 2016
  7. tanglefoot

    tanglefoot Whee!

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    No, no codes were read. That might be interesting to do.

    Mine appears to have been a sporadic incidence as well--only on that one, particular day. It hasn't reoccured either.
     
    #7 tanglefoot, Jan 20, 2016
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