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Help: Bleeding brakes after actuator replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jeff Moss, Nov 26, 2023.

  1. Jeff Moss

    Jeff Moss New Member

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    I replaced the brake actuator in my 2008 prius with one from a scrapyard. I had some issues with the 12v battery and connecting the techstream, but eventually got it charged/working. Then I tried to bleed the brakes using the techstream (selecting the brake actuator replacement option). I followed the instructions on the techstream and bleed the front two wheels (removed the relays, then put them back in when it said to). I had a little trouble with the front left wheel, but I realized I was letting up on the brake while the bleeder valve was still open, which was sucking air into the system. Once I started waiting to let up on the pedal until the valve was closed, the air cleared up and the fluid was clear for 8 brake pumps in a row.

    Then I went to the back left wheel as instructed (pushing the pedal down, not pumping), and I couldn't get air out of the line. I went through 2-3 quarts of brake fluid on this wheel, and while it was occasionally clear, there were consistently small bubbles present in the fluid.

    I don't think it should take 2-3 quarts to bleed the system, does this indicate that there is a leak somewhere, and how would I go about tracking it down? It seemed like the front two wheels didn't have an issue, they both had 8ish brake pumps with completely clear fluid. It was just the back left wheel that I couldn't get the air out.

    It's worth noting the techstream had the following codes when I hooked it up:
    C1241 - Low/high voltage
    C1252 Hydro-Booster Pump Motor
    C1253 Hydro-Booster Pump Motor Relay
    C1256 ACCumulator Low Pressure
    C1391 Abnormal Leak of ACC Pressure

    Thanks for any help!
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Base
    I believe you're replacement actuator is also bad You will find this very common you'll do this a few times more than likely No you shouldn't be pumping quartz out of the rear brake once you get to the rear you should be doing short bursts You will see some fine fine air bubbles in the mix if you're letting out lots of fluid like letting out big long streams there's no reason for doing this your person pushes the pedal you crack the zerk You see fluid come out count one two close the zerk person off the pedal Wait a couple seconds have them apply the pedal again You hear the motor and the pump you crack dessert You're not looking to make a bunch of turns You're just cracking dessert fitting see the fluid coming out without any air noises close it up If you have a tube attached to dessert and you're pushing this in a bottle or a cup you might see a few bubbles You're worried about big air noises coming out of the cup what you don't have teeny tiny micro bubbles are not needed to be worried about it the present time. Now go to the other side and make sure you don't have any air noises coming through the zerk with the fluid or lack thereof do it a few times on this side Make sure you have no air noises fluid squirting out close it up and now have that person apply the brakes Is it going to the floor halfway down does the person know this car if not you get in and check. Unless you drain the whole system which is highly possible you could have a mess. So in other words if you didn't clamp off the three feed lines coming off of the reservoir on the passenger side of the car feeding the strokes emulator and the ABS pump and accumulator which are changing You've already screwed up so you've let the whole system bleed out now you have a bigger mess to contend with.? Ideally you would have clamped off the three lines from the reservoir feeding the stroke simulator and the actuator and what have you so then when you unplug the feed line to the actuator that you're changing the stroke simulator and everything else stays full of fluid and doesn't take on air If the stroke simulator takes on air you're fixing to have a lot of fun read that section of the manual which is here on this forum somewhere. When you take one of these from the salvage car if it's a pretty much a wreck or a done deal usually I cut the lines the brake lines on the actuator so they kind of swag as I cut them with my dykes and the fluid that's in the actuator stays in the actuator It doesn't bleed out and then I turn it up on its side and I take out the broken lines and I put in these plastic caps and all of those brake line fitting so I keep the brake fluid in the actuator then I install it on the bracket set it in the car and I start adding the brake lines from the bottom up this way I'm not letting the actuator completely bleed out yeah there's an air bubble or too. But nothing that's going to seriously cause me to lose prime or my bleed or whatever you want to call it sounds like you have lost fluid in many places and now you've got to get it all fluid and no air again and that's kind of a big problem.
     
  3. Jeff Moss

    Jeff Moss New Member

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    2008 Prius
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    Okay, thanks! So there weren't huge air bubbles coming out of the left rear valve, it was all small bubbles. The front brakes had a few larger bubbles, but the bubbles in back were all small. I thought you wanted zero air, is it okay to have a tiny bit?

    Is there a way to test the actuator to see if it's good? When I held down the pedal it was pumping fluid to the back brakes. I'm just not sure what my next steps should be. I could try to bleed it again, but I'm not sure if that would do anything.

    Thank you for you time!
     
  4. Tombukt2

    Tombukt2 Senior Member

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    So now you have all the codes but not the low voltage? If so the corresponding orange lights are on on the dash and I would say that you're actuator is probably fubar or bad You should try bleeding again I usually just leave the relays out and bleed everything by drip bleeding because usually I've gotten very little air in the system as any at all and I just sit there and watch each wheel on my little stool and if any air comes out while it's drip bleeding you can see the bubble form on the end of the zerk fitting and I go around all four wheels and do this and if there's any question I go and do it again. And then I hook up tech and go through the bleed procedure and make sure I get through the pumping the brakes 30 times business and I hear those valves open. And then after that I usually try it in my driveway and up and down my street and I'm got a pretty good run there where I can get the brakes pretty warm. Then if I still have lights and all that I might check it again but usually that's just the bad actuator