Stuck ABS solenoid

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Deveak, Nov 27, 2025.

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  1. Deveak

    Deveak New Member

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    I’ve been driving it this way for the last 80k miles. I didn’t pay much for it but I want squeeze the last drop out of this car. Serious front end deer damage. I’m at 195k miles on a 2008. I have a c1344 code and no brake flow or pressure at all to the left hand rear side. Right hand side works. I took it to a mechanic with a proper tech stream enabled scan tool, he pulled the code and tried to bleed it with the scan tool and we walked it all the way back to before the proportioning valve. I think it may be a stuck valve. The original owner said it happened after he changed the brakes and jammed a cylinder back in with the cap on the brakes. I think he may have forced some gunk or debris into the valve. Is it possible to clean or fish a fine wire back into it and clean or unjam it? I’ll need to check and see if the solenoid itself is good but I’m pretty sure it is.
     
    #1 Deveak, Nov 27, 2025
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    Do you know if the mechanic cleared the code before trying to bleed the system? (won't bleed if you don't). Did the other rear brake bleed normally?

    I'm not sure what you mean by "proportioning valve". The brake actuator (ABS hydraulic unit) has the pump, accumulator, and solenoid valves all in one assembly. From there the lines go out to each wheel - no other valves.

    While I have seen ABS valves leak (not sealing or "stuck open"), I personally haven't heard of one being "stuck closed" - in theory the solenoid winding or wiring can fail, but that should set a circuit code.

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Nov 27, 2025
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  3. Deveak

    Deveak New Member

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    I thought it was a proportioning valve, traced it back to the firewall at least, no flow up to that point. He cleared the code and it came back.
    It does weep on that side, the rest flow and bleed fine.
     
    #3 Deveak, Nov 27, 2025
  4. ChapmanF

    ChapmanF Senior Member

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    Gen 1 had a proportioning valve, but starting with gen 2 that's just been added to the actuator's job description.
     
    #4 ChapmanF, Nov 27, 2025
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  5. pasadena_commut

    pasadena_commut Senior Member

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    More details on what the mechanic did please. Did he verify a clear tube all the way from the ABS unit to the brakes? Did he try hooking up up a tube and forcing brake fluid into that brake directly to see if it would work? Did he put any kind of pressure sensor on the brake end of that line to show that the ABS was not sending fluid down it?

    Seems a bit more likely that a clog would be in/near the little cylinder/piston thingy on the rear brakes than all the way up and in the ABS.
     
    #5 pasadena_commut, Nov 27, 2025
  6. Deveak

    Deveak New Member

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    He cleared the code, put it into abs pump mode and also had the brakes pressed in I believe. Traced the line up to the firewall so pretty much the ABS by the sounds of it. It seems to weep and dribble. I looked at a schematic, looks like there is a second solenoid that removes pressure back to an accumulator, could that be stuck open and preventing it from building up pressure in that line? I don’t think the ABS has failed. Pump runs and cycles pretty normal, plus I’m pretty sure the other side wouldn’t work in a complete pump failure, that’s why I’m thinking clog. No other codes.
     
    #6 Deveak, Nov 27, 2025
  7. pasadena_commut

    pasadena_commut Senior Member

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    So you're saying there was no pressure/flow at the ABS outlet port for that line? That would seem to narrow it down to the ABS.

    Except sometimes it is something else, see the 11th and 14th posts here:

    Brake code C1344 and warning lights! | PriusChat
     
    #7 pasadena_commut, Nov 27, 2025
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  8. Deveak

    Deveak New Member

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    Wouldn’t an ABS failure be complete with no pressure in both sides and hard pedal effort?
    I get full and powered braking on the front brakes and the rear right/passenger side. I was under the impression when you have an abs pump/actuator failure you lose all braking power.
     
    #8 Deveak, Nov 27, 2025
  9. ChapmanF

    ChapmanF Senior Member

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    The Prius brake actuator, an intricate box of valves and sensors with more responsibilities than just ABS, has many more than one way to not work right.

    What's more, its behavior when it has detected unexpected low pressure in one line and valves that line off to avoid fluid loss, could be considered a feature—a way of working right.
     
    #9 ChapmanF, Nov 27, 2025
  10. pasadena_commut

    pasadena_commut Senior Member

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    Is there a way using Techstream to confirm that this is happening?

    Or to go at it from another angle, once the car has seen such a problem and entered the "lock out" state, does it stay in it "forever", until some event clears the state, even if the original problem is resolved? If so, how would one tell the actuator to clear that state?
     
    #10 pasadena_commut, Nov 29, 2025 at 1:02 PM
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    I would expect you have to clear the code from ecu memory.

    Posted via the PriusChat mobile app.
     
    #11 mr_guy_mann, Nov 30, 2025 at 8:26 PM
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