Successful ABS actuator/accumulator replacement

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Gats, Jun 22, 2025.

  1. Gats

    Gats New Member

    Joined:
    May 25, 2025
    3
    3
    0
    Location:
    New Jersey
    Vehicle:
    2010 Prius
    Model:
    LE
    Hello all, I just finished my ABS actuator/accumulator replacement after a few hiccups - I wanted to post some notes here, in part because the community has been very helpful, and wanted to document some of the lesser known bits of information in case someone needs to google it in the future.

    2010 Prius, 3rd gen, north american, 168k. In very good condition overall, was driven mostly by a little old lady (my mother in law, so i know it's not a story) mostly in northern CA but also recently in the northeast. Well maintained, in the later years, mostly by me. My daughter drives it mostly now, since grandma doesn't drive much anymore.

    Daughter was driving it, with me, back home from an event, and the brake light(s) went on - traction control, ABS, and BRAKE. There may have been another, I can't recall. Luckily I was there in the car, we pulled over and I test drove it. Brakes were soft for sure, but I couldn't tell exactly how soft since I don't often drive the car. After a few minutes googling and checking to ensure we still had brake pressure and no leaks I felt comfortable driving it the 10 min home on side streets. Halfway home, the lights all went away, brakes firmed up and it drove normally.

    Some research at home indicated that the ABS system was likely starting to fail, either the accumulator wasn't creating enough pressure (the bottom thing) or the ABS module couldn't hold the pressure (the top thing). Car is in good condition and enables my teenager to get around so I took it for a quote. Two quotes came back at $4000+ so after some consideration I decided to do it myself. Bought both parts at Olathe Toyota (those guys are awesome btw) for $1200. FWIW the part numbers for my 2010 were 47050-47140 and 47070-47060. These are the current replacement parts as of June 2025.

    The physical replacement of the parts is straightforward, watch enough youtube videos and you can figure it out. I won't get into it. It takes basic tools, although I will say that having a set of line wrenches is very helpful, I highly recommend them to ensure you can remove/tighten/loosen the lines without stripping and rounding the fasteners. Also a set of hose clamp pliers is helpful also. Honestly if you're going to attempt this repair I highly recommend both if you don't have them. Don't screw up your $1200 repair because you used an open end wrench instead of a $5 line wrench. Buy the right tool, cheapskate.

    Parts installed without much issue, although positioning the accumulator with the little shock absorbers, is a pain. Parts installed without an issue.

    First problem I came to is the car would not go IG-ON mode which is sort of required for the air bleeding procedure. When I hit the button once, it would automatically go into READY mode. I could not figure out why so I bled the brakes out normally and it seemed to work, I got it to the point where I had hydraulics at least. There did not appear to be air in the lines, or in the ABS module. But without being able to go to IG-ON (the mode where the car is on but the engine is off), I could not successfully know that I did air bleed correctly, and I could not do the linear valve offset reset.

    One thing I noticed was that when I turned the car on the brake lights automatically turned on at the rear of the vehicle. Eventually i figured it out, and it was very simple - the brake switch that contacts the brake pedal, needed to be re-adjusted. It's a simple twist and click to adjust.

    With that done, I re-did air bleeding on all 4 corners and the abs module. The scanner I used was the Foxwell 614 elite. That seemed to work fine (and to my credit there was no air in any of the lines from the first bleed)

    With those codes gone the only ones remaining were for linear solenoid valve offset and LSV learning undone.

    I tried the procedure through my scan tool and it would go through the procedure but nothing would happen. No noise, no blinking lights on the dash as I've seen in other videos, nothing. After some research i suspected battery, so I checked it and it was at 11.8-11.9, it's a 6 month old battery but i put it on the charger anyway. After a while i checked it again and it put out a steady 12.1 and i tried again and still nothing.

    I'll skip all the intermediate troubleshooting steps but the solution ultimately was, the 12v battery. I hooked it up to my van like it was being jump started, and apparently that was finally enough voltage to do the linear solenoid valve procedure. Unlike before when nothing happened, this time, there was all sorts of whirring clicking and air pressure noises during almost the entire procedure. I actually then cleared the memory and did it again.

    Regardless it worked, and no i just need to put the rest of it back together (wiper arms, motor, cowling, etc). Test drove it, everything works fine. Final cost ~$1500 (scan tool was an upgrade over my old reader) and many hours of troubleshooting, but saved many thousands of dollars.

    Again I just wanted to document this in case anyone searches in the future and is stuck by either the brake switch issue or the 12v issue. I have spent many hours on this site and others learning how to do this, and that wouldn't be possible if others hadn't documented their experiences so I wanted to pay it forward.
     
    #1 Gats, Jun 22, 2025
    CR94, wukong sun and Brian1954 like this.
  2. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    27,695
    18,288
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    This is a very common part of many people's "I replaced my actuator" PriusChat stories.

    It probably shouldn't be as common as it is: if I had caught you in time, I would have suggested a very careful recheck that you got the new actuator fully seated down on the firewall, nothing stuck behind it (no old gasket left behind or the like). If it's not fully down on the firewall, the pushrod won't extend the right distance into the cabin, the pedal will be too low, and won't contact the switch. Probably also the stroke sensor reading will be wonky.

    Once the actuator really is for sure seated right down on the firewall, it is still possible the pedal is too high or too low: that's adjusted by turning the threaded clevis on the end of the pushrod (after loosening the lock nut).

    [​IMG]

    (Note the reference distance is from the bare floor sheet metal, after folding the carpet/pad back out of the way.)

    If the switch was working right when the pedal height was correctly adjusted before, then when you've done the work and you get the pedal height correct again, the switch will still work right. So times when the problem is really the switch adjustment should be very rare. When the problem is something else, adjusting the switch is a "now you have two problems" kind of fix.

    Using your scan tool, you can also view the live data list for the skid ECU to see the pedal stroke sensor reading. It ought to be one volt (allowable 0.8 to 1.2) in gen 3 when the pedal is not pressed at all. If it is out of that range, there is a stroke sensor adjustment, but again, if it was ok before the work was done, then you should make sure of the pedal height adjustment first, before going and tweaking the sensor.


    Note to self: if my car ever needs this job, I'll probably just note the stroke sensor reading before I start, then adjust the pedal height later to get the same reading, and not fuss with folding the carpet back to measure from the pedal to the bare floor.
     

    Attached Files:

    • ph.png
      ph.png
      File size:
      6.5 KB
      Views:
      0
    #2 ChapmanF, Jun 22, 2025
    Last edited: Jun 22, 2025
    CR94, Gats and Brian1954 like this.
  3. Gats

    Gats New Member

    Joined:
    May 25, 2025
    3
    3
    0
    Location:
    New Jersey
    Vehicle:
    2010 Prius
    Model:
    LE
    Great info ChapmanF thanks for adding it to the thread. Honestly I was kicking myself once I figured out the brake switch, it's always the simple things that you end up overlooking. FWIW I compared the thread length of the old clevis to the new one prior to installing (did not need any adjustment out of the box), so I may have mentally eliminated that from my troubleshooting checklist. I don't recall if I removed the switch in order to help get the old part out or not, and then reinstalled it at the wrong level (probably did this)

    Hopefully this thread helps someone else down the road. Also the fully charged battery thing is no joke, I'm not sure what the cutoff is for it to not start the LSV procedure but apparently it's pretty high. So if you can't get the LSV procedure to start, hook up a jump pack or another vehicle to ensure that the voltage isn't the issue.
     
    #3 Gats, Jun 22, 2025
  4. S1n

    S1n New Member

    Joined:
    Saturday
    1
    0
    0
    Location:
    USA
    Vehicle:
    2012 Prius
    Model:
    Three
    Great info here. I replaced my ABS accumulator and actuator (whatever they are, there are so many different names on the internet) yesterday, and I wish I had read this thread before.

    Now, I am having two major problems. First, like you, I had the brake light stay on. The brake switch was not touching the pedal, so I was not able to bleed. As a temporary fix, I wrapped that metal part with duct tape so that it hits the brake switch. It worked and I was able to bleed. Seems like as @ChapmanF said, I need to recheck if the actuator sits flat. My question is: can I just loosen the 4 bolts under the pedal and wiggle the actuator from the outside without taking the lines off? I hate the bleeding procedure and am afraid to do it again. Also, I am worried that my front left bleeder screw might be stripped because it was neither 8mm nor 10mm weirdly.

    Second problem: after the replacement yesterday, I checked the car this morning and realized the brake fluid is close to the MIN line. I don’t see apparent leaks, so I assume it was a small leak. I tightened the brake line screws again and put napkins under the lines and hoses. I'm waiting until tomorrow morning to see the level. I hope the leak stops, but I’m afraid I may have damaged the brake lines while moving the actuator in and out. I might have over-manipulated those lines because I had a very tough time getting it in.

    Anyway, besides those problems, I wanted to share some of my experience for anyone else trying this.

    The videos I used on YouTube were titled "2010-2015 Prius Brake Bleeding after ABS Actuator and Accumulator Replacement with Topdon Topscan" by Automotive Insight for the general steps and titled "2010-2015 Toyota Prius ABS Removal" by The Yota Channel because it had a much better angle for removing the accumulator. What I would suggest is, make sure you don't overmanipulate the brake lines. It becomes very complicated when putting the actuator back in, so make sure you get familiar with the brake lines' general shapes. I also realized that I spent an unnecessarily long time taking the pin out of the brake pedal. It's simple: you just need to push both sides of the clip towards the outside and pull it up with some force. Don't make it complicated.

    When removing the 10mm bolts on the accumulator, make sure take your time and move slowly. After breaking the nuts and loosening the bolt, use your hand to loosen it and take it out slowly. Those rubber grommets are prone to fall as well. Wiggling the accumulator smoothly helps to get the rubber part. When putting the new accumulator back, the 10mm bolt on the far side is tricky. I dropped it a couple of times but thanks to a small towel i put under the accumulator's 2 bolt places, it catched and I was able to get it with a magnetic stick, very strongly suggested. Then, when putting the actuator back, make sure you don't have anything between firewall and actuator and make sure it is flat and strong, which obviously I did not and am having a problem with brake pedal and brake switch in the car.

    After replacing these two, now time to bleed. I used Topdon Topscan and it works great. It also does linear solenoid calibration and yaw sensor calibration. After my search on internet seemed like Topdon Topscan is one of the cheapest scan tools that can work on a prius. Bought it on Amazon for fifty-something bucks. However, I made two mistakes in the bleeding process. 1 I did not have a battery charger, and 2 I did not jump the 4 wheels and instead tried jack the car one by one since I did not have 4 jack stands. While I was bleeding the battery died and bleeding failed. Then I got a new battery, jack stands and made sure everything was ready before starting bleeding. The car was jacked from 4 side, no wheels, new battery. Followed the instructions and was able to bleed this time without issue.

    However, one issue I had was bleeding screw sizes. Rear screws are 10 for sure, but fronts are not. Many videos did not mention that so I assumed it was 10mm. Then, I saw another video claiming fronts are 8mm, but it wasn't an exact fit as well. So I tried other sizes in my set and found a close one. I used the first one that seemed working ok, but stripped the screw a little, so I am afraid I would have to bleed it again someday. So make sure you have a set with different sizes next to you in case you need.

    Anyways, I am still having two important problems, and it is not a success story yet, but overall, this is a doable project. There are a lot of videos and forum posts that you can benefit from, and I hope my post helps you as well.
     
    #4 S1n, Jan 4, 2026 at 10:45 PM
(You must log in or sign up to post here.)