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Dash indicator lights turned off but DTC blink codes still present

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by roonsta, Feb 1, 2024.

  1. roonsta

    roonsta New Member

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    Montour Falls, NY
    Vehicle:
    2013 Prius c
    Model:
    One
    Hi all, i'm a new poster here. I'm working on a 2013 Prius C. The other day, after driving for a few hours in snowy and slushy conditions, all four brake system indicator lights lit up on the dash [BRAKE, ABS, the skiddy one (VSC), and ((!))].

    I used the trick from this excellent post to get the blink codes. There were six of them across three of those four indicator lights.

    They were:
    ABS 31, 32, 33 -- Issues with the speed sensor circuit for the front-right, front-left, and rear-right speed sensors
    ABS 41 -- Low battery positive voltage
    EBC ((!)) 49 -- Open in stop light switch circuit
    VSC (skid) 64 -- Stop light control relay malfunction

    I haven't noticed any changes in performance, perhaps a bit of extra play in the brake pedal or having to push a bit more firmly than usual, but not as much as on a car without power braking.

    Based on these codes (and lots of message boards and youtube videos XD), i came up with a whole diagnostic plan. The first step was to check the 12V auxiliary battery. I checked it thru the diagnostic tool on the AV display and it seemed kinda low (14.2V while driving, 11.8V when no systems were on, 11.5V with systems like headlights and air conditioning on). So i tested it with a multimeter and it seemed a bit low but passable (12.5V with car turned off, 12.37V with no systems on, 12.2V with headlights and AC on). Which was a bummer because i was really hoping it was as simple as changing the battery.

    Disheartened, i packed up the multimeter and got in the car for the short drive home. A few minutes into the drive, all four of the brake-system indicator lights flicked off. Bizarre. When i got home, i checked the blink codes again. All six of the above listed codes are still blinking out. Which leads me to two questions:

    1. Are blink codes only current codes or do they also display past codes that are no longer active? At this point, now that the lights have turned themselves off, should i clear the codes?

    2. Any thoughts on if there is still likely to be an issue in the brake system now that the lights have turned themselves off?

    Thank you!!!
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Vehicle:
    2018 Prius c
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    Two
    It's not terribly uncommon to get wheel speed sensor errors when driving in wet icy slush.

    Those may have been the only active codes, the others may have been stale from previous presentations.

    Probably the best course of action is to hold for a spot of dry weather, clear the codes and see how it does.
     
  3. roonsta

    roonsta New Member

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    2013 Prius c
    Model:
    One
    Thanks @Leadfoot J. McCoalroller . So to confirm, the blink codes include all stale codes if they are not cleared?

    Would it be reasonable to clear all codes now just to see which ones come back (and, thus, are still being triggered or considered active)?
     
  4. ChapmanF

    ChapmanF Senior Member

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    I've always thought only current codes get blinked.

    Maybe I was wrong.

    Come to think of it, I seem to recall that in some generation, for some ECU, there was a way to blink either current or saved codes; maybe something to do with connecting the Tc to CG jumper before or after the ignition is on. But I don't see anything about that in the brake section of a Gen 3 manual, which is probably the closest thing I've got to a c manual. So as far as this story here, I just don't know what to say.
     
  5. roonsta

    roonsta New Member

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    Location:
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    Vehicle:
    2013 Prius c
    Model:
    One
    haha @ChapmanF, thanks for weighing in. i'm also not sure and haven't been able to get access to the repair manual for this car. If anyone has access to a 2013 Pirus C repair manual that they'd be able to point me towards, that would make this much, much easier XD