ABS accumulator vs modulator

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by KevinMiller, Jul 21, 2025 at 3:36 AM.

  1. KevinMiller

    KevinMiller New Member

    Joined:
    Monday
    2
    0
    0
    Location:
    Los Angeles
    Vehicle:
    2007 Prius
    Model:
    LE
    2007 Prius, 107,000 miles

    I am not car-mechanical savvy, as you will see…

    I got all the dashboard brake lights a week ago: BRAKE, (!), ABS, VSC . Still able to drive, but doing so carefully, no freeways.

    -Brake fluid is just below max.
    -12V battery reads 11.3V when not turned on, 14.1V after starting the car.
    -It has been making noise for quite a while; two mechanics told me it was the accumulator making that noise, but didn’t say it was something to worry about. But now here I am…
    -Mileage is lower; tire pressure is fine, so I don’t know if that’s related

    Got an Autozone OBD readout: codes C1256, C1391, C2318 (secondary DTC)

    Mechanic #1 quoted me $3000 (in Los Angeles) without even looking at my car.

    Mechanic #2, did a diagnostic, cleaned voltage connector, found “faulty ABS unit”, quoted me $2600, but for a modulator valve and labor, not a brake accumulator, which is what the OBD codes indicate.

    Wondering if this makes sense. Taking it to be fixed today.

    Thanks for your thoughts.
    20250711_235937.jpg 20250713_195136.jpg 20250713_195150.jpg
     
  2. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    12,287
    2,165
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Whatever you're calling it you're buying the same part . It's all in one unit.
     
  3. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,679
    8,521
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    Buy the part and I’ll have someone install it for $500. New part is the way to go with your low mileage car
     
  4. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    9,660
    5,949
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
  5. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    26,608
    17,428
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Different Prius generations have divvied up the brake components differently. As long as your car is a gen 2 (2004–2009), your accumulator is part of the actuator (or 'modulator') assembly, so you don't need to worry about it. In some other generations, they're in separate assemblies.
     
  6. KevinMiller

    KevinMiller New Member

    Joined:
    Monday
    2
    0
    0
    Location:
    Los Angeles
    Vehicle:
    2007 Prius
    Model:
    LE
    Thanks for the info.

    Thanks for the offer. My car was already at the mechanic by the time of your post. I’ll keep you in mind for the future.

    Thanks. I’m not sure exactly what you mean by ‘covered by Toyota’. If you meant it was under warranty, unfortunately that wouldn’t apply to me since my car has long been out of warranty, but good to know.

    Thanks. I appreciate your deep knowledge of Priuses. I’ll probably buy another next year, maybe 2 or 3 years old, if you have a recommendation/preference for one year’s model over another.

    Meanwhile, my car still makes noise when I brake. I asked the mechanic about it when I picked up my car yesterday (he bled the brakes and he replaced the ABS unit), and he echoed what another mechanic had told me last year, that ‘old Priuses make this noise.’ Do you have any thoughts about this?

    I uploaded an audio file of the noise here:
     
    #6 KevinMiller, Jul 24, 2025 at 5:31 PM
    Last edited by a moderator: Jul 24, 2025 at 6:02 PM
  7. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    12,287
    2,165
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    The ole Honking. Noise
     
  8. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    9,660
    5,949
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    That noise is not normal and may mean he did not do the special Techstream flush need after brake actuator replacement.

    Covered by Toyota in this sense means extended coverage beyond the regular warranties.

    If you are not the original owner you want to update your information to get notices.
     
    #8 rjparker, Jul 24, 2025 at 6:52 PM
    Last edited: Jul 24, 2025 at 7:01 PM