ABS/Brake warning light magically disappeared?

Discussion in 'Generation 1 Prius Discussion' started by vaughnstark777, Jan 22, 2017.

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  1. vaughnstark777

    vaughnstark777 Member

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    2001 Prius
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    I
    I bought a 2003 that had been sitting for a couple of years with the hv battery removed and sitting in the trunk. After I replaced the battery with a good one and managed to get the ice to start and run. There was the telltale high pitched screeching noise with the ABS and Brake warning lights on. So as I was looking through the forums and whatnot looking for the solution to the problem I left the key on and let the ice cycle on and off. Low and behold, after some time of this, the screeching noise disappeared. But since the idiot lights were still on I kept looking and let it cycle. After I read as much as I could I decided to take it out on the road and get it up to speed and test everything else. I decided to hammer the brakes a few times to see if that ABS would work or if it would actually lock up the brakes. The ABS seemed to work but not as I thought it should so I tried it again. We'll strangely enough they seemed to work fine this time and the lights disappeared. I'm a little weary of cars that seem to fix themselves so I'm inclined to believe that the long sit might have caused things to gum up, as it were, and a little workout loosened things up.

    I'm just wondering if our veteran Gen 1 enthusiasts could tell me if my hypothesis is on the right track or if anyone has had a similar experience?
     
    #1 vaughnstark777, Jan 22, 2017
  2. Brian in Tucson

    Brian in Tucson Active Member

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    I've been doing brake work lately, replacing a broken booster pump. The lights and tone were constantly on. After I fixed the pump, techstream cleared the codes and the light and tone went off. As I was bleeding the brakes, if I pumped 'em, the light and tone would come back on until the booster pump could catch up.

    I hypothesize that the ABS computer senses a low fluid pressure and set off the warning lamps and tone. Not so much a hard code set, but just a warning kinda like the brake fluid sensor does. It may be that a solenoid was locked open or closed and pumping the brakes allowed it a little extra pressure to activate a solenoid. Count your blessings. You got off easy.
     
    #2 Brian in Tucson, Apr 26, 2017
  3. vaughnstark777

    vaughnstark777 Member

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    It came back on the next time I started it. I bought a factory set of manuals and will be tackling, what I've come to understand, is not a fun job.
     
    #3 vaughnstark777, Apr 26, 2017
  4. Brian in Tucson

    Brian in Tucson Active Member

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    I think I couldn't have done the brake booster without the manual--or at least it would have been a lot harder. For me, the pain of working on my Prii's is not the actual labor, it's the cost of the parts. Fortunately, there have been 3 gen 1's in the local u pull it style junk yard in the past 6 months.
     
    #4 Brian in Tucson, Apr 27, 2017
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