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ABS module went out ... again

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by chronon, Feb 26, 2021.

  1. chronon

    chronon Active Member

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    went to leave road and continuous tone .. oh gee .. what could it be .. nuthin but the thing u just replaced ...

    ABS accumulator break pump module ... syptoms : break pedal spongy and braking slow with pedal going all the way to floor (like pump is no longer working) ...

    the replacement was a yard pull that someone else did and resold to me .. -- now to get my money back i have to pull this unit out and get it back to him ... this is just gonna double my fun factor for this weekend and i'm so excited i dont know what to do ......

    NOTE: *** the replacement was a 'revision' or somewhat newer module than what was already in the car ... ( the replacement did have the error that it showed (viewed by snap-on scan tool as well as techstream) that Right Rear pressure sensor was reading high (5v) when it should be somewhat half or less .... ) - was able to drive car with 2 fronts and 1 back brake mostly as normal ..... until today ...

    ***have heard of this ' under dash resistor' needing to be matched up to each particular module .. i did no such thing ..
     
    #1 chronon, Feb 26, 2021
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  2. chronon

    chronon Active Member

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    so i got the techstream out and had 3 ..
    C1202 'fluid brake level low'
    C1343 hydraulic system problem
    and the same problem i know about which is RL pressure sensor as seen on the
    *C1364 freeze frame data ....

    So i put fluid in resoirvor just under max (it had fallen to about min lvl) ...
    C1202 went away .. took for 2 min spin .. seems ok ? wondering what the new c1343 is about ..
    after i checked resoirvor after a drive it seemed higher than max level ( it went up) ...

    Took about 3 weeks for it to fall from max to min ? slow leak somewhere ????
    more time and more surprises to come !!!! woo hoo
     
    #2 chronon, Feb 26, 2021
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  3. Todd Allan McIntyre

    Todd Allan McIntyre New Member

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    I haven't ever replaced one but I think when you change it you have to use a high level scan tool to have it do the bleeding? Sounds like you have air in the lines.

    Posted via the PriusChat mobile app.
     
    #3 Todd Allan McIntyre, Feb 26, 2021
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  4. chronon

    chronon Active Member

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    i did pay a friend of family mechanic to use his fancy Snap-on scan tool to do an ABS bleed .. (because my flaky techstream crashes when attempting) ... so there's that but He didnt do antyhing other than run his app .. he didnt open any bleeder valves at the wheels ..
    so .. .. who knows .. but I found the vaccuum device at the wheel cylinder effective as well as stick shoed on pedal and pushed under steering wheel .. the key thing is that the hyrdaulic pump pushes fluid to the front brakes where 2/3 of the braking happens .. any additional at the rears is bonus .. ( have fun improving your 60-0 time ) .... an additional bonus is the 'pulsing - anti-skid 'action of the ABS system
    a controlled stop is so many times safer/ better than skidding and loss of control ... .... ABS great for sandy/wet/icy road surfaces ...
     
    #4 chronon, Feb 27, 2021
  5. ChapmanF

    ChapmanF Senior Member

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    A lot of that could be true if the brake system you were describing were like the one that comes in a Prius.

    Working on the one that comes in a Prius, though, I would want to get the air out of all of the passages.

    That's pretty goofy. Just step through the prompts of the bleed program without bleeding anything?

    There is, amazingly, one situation where that actually makes sense, but it is only if C1451 is the only code and you know there isn't any air in there.

    In any other situation, like after you've just replaced an accumulator or actuator, you know full well there is air in there, so the diligent mechanic will go through the long-form bleed program and actually open the bleeder valves when it says to. If that isn't done, there's no reason to expect the brakes to work right.
     
    #5 ChapmanF, Feb 28, 2021
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  6. chronon

    chronon Active Member

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    ** Well .. ..I was a bit agitated that there was no opening of wheel valves during his operation .. but then again .. he did fill and add dye to my AC refrigerant some months ago without pay so i imagine there was hesitancy to do much manual labor as he probably goes on weather he gets paid by wether he got paid on the last visit ... and as the saying goes 'always pay your mechanic to ensure top level maintanence on each visit' .. ...

    If I were to post 60-0 times .. would there be any data to compare it with + ? all kinds of 0 - 60 data though .. about 10-11 seconds ....

    ***** I don't see anybody, except in some utubes , mentioning much about the __matching resistor to the particular ABS module__ (that goes under the dash in the steering area) ... that errors on the dashboard will continue also until this change is made ...
     
    #6 chronon, Mar 3, 2021
  7. ChapmanF

    ChapmanF Senior Member

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    and after all, bleeding brakes without opening the bleeders is at least as good as a fillup without opening the fuel door.

    That might be because I don't see any indication of that being the case. The resistor gives you a 'low' pump speed (there are two relays switching power to the pump, and the resistor is in the path from one of them, so the ECU has the option of closing that relay when it wants to run the pump at a reduced speed). The only thing the Repair Manual says about the resistor is if you don't use the one matched to your actuator, you might have increased pump noise. Nothing about any errors that would result.
     
    #7 ChapmanF, Mar 3, 2021
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  8. chronon

    chronon Active Member

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    sho nuf car do be sofistikated .. by why it be lacking a computer to monitor break pressure ..
    it has break pressure sensor for each will .. but if dere be sum air in dat dang line why dis smart azz car cant be reportin dat air ?
     
    #8 chronon, Mar 3, 2021
  9. ChapmanF

    ChapmanF Senior Member

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    When you've got a big can of 2,000 psi brake fluid and some valves, bubbles of a certain size aren't going to prevent the target wheel pressure being reached. The valve just stays open a fraction longer and enough fluid flows to compress the bubble and reach the target pressure anyway. Then when you release the brake the bubble expands again and more fluid returns to the reservoir. If the effect is large enough there'll be codes set, if it's smaller there might not.

    But weren't you saying you do have codes set?

    When I was in college there were some awk scripts floating around that you could run on any old file of text and get it 'translated' into various 'dialects'. I think your last post got run through one of those. (I thought the 'valley' script was a hoot, would make your post into a Valley girl.)
     
    #9 ChapmanF, Mar 4, 2021
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  10. chronon

    chronon Active Member

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    I think .. his daughter was pretty cute in that 'valley girl' vid of 1986? .. I think she was about 16 ...
    (1 of Frank Zappa's daughters) that is ... i thought the ebonics were more of .. .. ok ..back to subject ..

    Thx 4 the planation of the plantation .. it volleyed well in the deep well of thought ... -
    You must have some good engineering background ---

    Yes I do have codes set .. at least 2 .. C codes .. the one for thepressure sensor and the other new one .. (listed above) ..

    Well .. Getting new tires and so far replaced michelins in the back .. they were 185 / 60's .. short.. so car handling and driver 'tilt' was not great .. huge improvement putting the 185/65's on back .. .. will be replacing the 'niki's' on front soon with the same as on back .. so my brakeing effect will be more evenly distributed ... ;)
     
    #10 chronon, Mar 4, 2021
  11. chronon

    chronon Active Member

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    so .. i checked the brake fluid and the level is inbetween .. so when i filled it to 'max' it has not dropped 1l2 way to 'min' -- somewher sumthin is slowly going out of the system.. so slow that about a pint? is lost about every month ...
     
    #11 chronon, Mar 6, 2021
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