Need help after replacing ABS module and accumulator pump

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Gats, May 25, 2025 at 7:52 PM.

  1. Gats

    Gats New Member

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    2010 USA Prius. 165k miles. Old lady driven (really)

    My daughter borrows this car regularly since grandma doesn't drive much anymore. Daughter reported the dreaded ABS, traction, brake pad warning light holy trinity, with soft pedal. Then while driving carefully and limping home, lights went off and problem went away (supposedly).

    She reported to me and I looked it up, determined that both the ABS module and accumulator should be replaced. The pump was running for a couple of seconds, every 10-15 seconds, so it either wasn't building pressure, or it wasn't holding pressure. So I ordered the ABS module and pump accumulator from Olathe Toyota (great place, fast shipping, low prices, good followup) and swapped in the parts without much issue (I am a pretty experienced parts swapper)

    HOWEVER,
    I can't successfully complete the bleeding procedure. I have a Foxwell 614 Elite diagnostic tool with ABS bleed, linear offset, and zero down functionality. I followed the procedures to bleed, and it seemed to successfully bleed out fluid electronically from both rears. I did a normal bleed on the fronts and it also completed normally, got some debris out of the lines, pushed new fluid into the lines, no air that I could detect. Ran the solenoid bleed, and it seemed to go fine, pedal seemed pretty firm at that point. But the lights remain.

    The only issue I had during this time was the bleed procedure wants READY off but I can't get that state. I push the power button and READY comes on immediately. Also, the brake lights are on, as if i'm actively pushing the brakes. And the parking brake light is on regardless of whether the parking brake is on or off.

    I think if I can solve that, and get it to a state where READY is off, then I can try the bleed and calibration procedures again. What's my move here? Do I try to adjust the pedal position? I checked before install and it was set at the same length as the old one. How do I get it to reset?

    I can actually drive it ok (up and down the driveway at least) and it feels pretty normal at super low speeds so eventually if I can't figure it out I can take it to Toyota, but I'd love to be able to figure this out.

    Thanks Prius fam.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    If you want to be out of ready you want to be an ACC mode like in an old car where you turn the key to the first step and everything lights up to do this in the Prius you do not touch your brake pedal with your foot at all you push the power button once remove your finger and then push the power button again doing nothing with your foot and all the dash lights light up but there's no ready light correct try it now or when you're awake I have not had to completely bleed and reset linear valve offset and all that on the generation 3 they didn't make it long enough for us to get to that point they blew up all I do know is the Gen 3 is a pain in the butt to change those two parts on and then the rest of it is pretty much like the cars I drive the generation too once you get to the point of bleeding what worries me in your situation is debris came out of the line and you blew fluid back up into the line like through the bleed fitting oh boy generally on ABS cars they say you don't want to be back pumping the fluid squeezing calipers down without the bleed screw cracked to let the fluid out and then close it immediately before it stops that sort of thing but I don't know this to be fact but they say you don't want to be doing that. So see if you can put it in the ACC mode and run your linear valve offset and the other thing you need to do and see if that puts your lights off I have blood generation twos before and still had the lights on. Because I won't clear and reset the learned value of the linear offset valve until I'm fully bled and lights remain the minute you clear out what the car remembers for the linear valve offset then you have to reset the linear valve offset and if something doesn't go right it could be problematic. But you're using new parts so this is the standard procedure I just usually don't clear out my learned linear valve offset values until after I'm completely bled and I have a good pedal but I still have lights and a lot of times I have a code telling me that the linear valve offset has been unlearned or something to that effect then I will go try to learn it.
     
  3. ChapmanF

    ChapmanF Senior Member

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    That "holy trinity" is pretty much everywhere (religious scholars would agree), because the three logical functions of the ECB/ABS/skid ECU keep tabs on each other, and they pretty much all have their own comments to make even if just one of them has a problem. Sometimes two of them just have codes that mean "go look at the third one."

    The main takeaway from that is that there isn't much that's special about seeing those three come on together. Nearly all of the couple hundred conditions, from expensive to trivial, that light any of them will light them all.

    ... which is what happens if you push the power button while the brake-pedal-is-pushed switch is made ...

    ... which is also what happens when the brake-pedal-is-pushed switch is made.

    My first, second, and third guesses will be that as you mounted the new actuator, something is keeping it from being fully flat against the firewall (leftover gasket from the old one, maybe? or just cockeyed), so the brake pedal, when attached to the pushrod, is not returning as far up as it needs to in order to depress the pedal's-not-pushed button.

    Some people who get into such a situation rush immediately to change the adjustment of the pedal-to-pushrod clevis or the adjustment of the pedal's-not-pushed button, but I would resort to either of those moves only after checking very carefully, and maybe with other eyes on it, that the actuator really is seated down flat where it needs to be.
     
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  4. Tombukt2

    Tombukt2 Senior Member

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    Yeah that false adjustment has happened many times right here apparently it's a real problem looks like it's reared it's ugly head again
     
  5. wukong sun

    wukong sun Junior Member

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  6. ChapmanF

    ChapmanF Senior Member

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    Already switched the brakes. Brake switch is probably fine. Just not being switched properly by the switched brakes. Need to make sure the pedal comes up to the switch, after the switch.
     
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  7. Tombukt2

    Tombukt2 Senior Member

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    Look at the piece that goes on your firewall that you just spent all that time mounting is it flush look at the boat holes or the boat studs that go around the unit where it goes to the firewall I don't know if you can see in there good or not but it sounds like you left the old gasket on and it's holding you off the studs a bit or something like that and so now when you offered up the new unit and the old gasket is stuck on the firewall or something and you add a gasket also and then push the unit new up against the firewall you got double the thickness of space now and when it's screwed and bolted down the brake switch is not touching like it used to when it only had one of the gaskets in place