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ABS light is on

Discussion in 'Gen 2 Prius Main Forum' started by Larry Kosher, Apr 18, 2022.

  1. Larry Kosher

    Larry Kosher New Member

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    Hello.
    05 Prius, had been sitting for a while before getting acquired by a friend of mine. The extended outside parking resulted in the rear brakes rusted out. We've got a replacement from a local junkyard. That included bearing assemblies and all the drums, etc. Having all that installed we are struggling to bleed the system. I've got a cheap VCI USB with teachstream software and we were trying to use that for the bleeding procedure. However, the ABS light is always on and the active test procedure in teachstream always fails. A while ago there was a trouble code regarding an open circuit for the RL vehicle speed sensor. It took us a while to investigate the issue, and I'm not sure what was it at the end, but that trouble code is gone. Not the ABS light, however. Thinking that it might be a damaged ABS/skid module we swapped in another one from the junkyard. That didn't help. However, there was a moment when the brake red light on the left of the dash wasn't on. Now it's back on again. Of course, all the fuses and relays checked/swapped from a working car, etc. How do we investigate the issue? What could it possibly be? No trouble code in the ECU now, resetting the ABS light doesn't help - it stays on.
     

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    #1 Larry Kosher, Apr 18, 2022
  2. dolj

    dolj Senior Member

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    That doesn't make sense. If you have a trouble light for the ABS showing on the dash there will a one or more codes in the ABS/TRAC/VSC section of Techstream. Finding out what they are will go a long way toward knowing on what to focus.
     
    #2 dolj, Apr 18, 2022
  3. ChapmanF

    ChapmanF Senior Member

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    You could also use the code-blinking method to see if any codes are reported that way. I usually reserve that advice for people who are using scan tools other than Techstream; Techstream really ought to have no difficulty here. But as dolj said, the light with no codes makes little sense.

    (It could, of course, be a malfunction of the light itself in the combination meter. You can probably find steps in the repair manual for troubleshooting that. But that seems highly unlikely to be the story here, with the background you've given.)
     
    #3 ChapmanF, Apr 18, 2022
  4. Larry Kosher

    Larry Kosher New Member

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    Okay, teachstream now reports these. These weren't there before. What's going on? I'm certain it is not a bad 12-volt battery. I did test that.
     

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    #4 Larry Kosher, Apr 19, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    If you're confident the power is ok, then it is likely those codes mean what they say, and you have communications issues to diagnose.

    That's a bit fiddly to do, but you'll find the information for doing it in the "CAN communication system" section of the repair manual.

    Toyota Service Information and Where To Find It | PriusChat
     
    #5 ChapmanF, Apr 19, 2022
  6. Larry Kosher

    Larry Kosher New Member

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    I am ashamed to confess, that it turned out to be a bad ground wire from the 12-volt battery. All is fixed now, thanks, everyone!
     
    #6 Larry Kosher, May 2, 2022
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    Well you fixed it, so that's good. It ain't likely that you'll overlook THAT particular bit again- that's how you learn. Make a mistake- then fix it.

    Posted via the PriusChat mobile app.
     
    #7 mr_guy_mann, May 3, 2022
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