Gen 3 2010 Prius - Troubleshooting ABS Brake Codes 33,34,36 - VSC 43

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Lynard55, Mar 7, 2020.

  1. Lynard55

    Lynard55 New Member

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    I have done a bit of reading and figured I would make a quick post to see if those of you who know much more than I do are able to help me out.

    After filling my front tires with air the other day at the gas station, I turned back on my 2010 Prius with 113K miles and the dash displayed several brake warning lights on the dash. Prior to this there were not any known issues and it has been over a year since I replaced the rear pads and rotors. Admittedly the front pads and rotors may be in need of replacement. Since the codes were displayed the brake pedal feels "soft".

    After doing a bit of research I was able to get the error codes by shorting CG4 and TC13 located on the DLC3 connector. Below are the codes that I determined what I believe to be the "problem":

    Note: These all came on at once just after the car was started

    ABS: 33,34 ----> RR & LR Speed Sensor Malfunction
    (!): 36 --------> LF Foreign object attached to speed sensor ---- Seems kinda odd
    VSC: 43 --------> ABS Control System Malfunction ---- Assuming a general code that is a result of above

    *** Electronic Power Steering: -----> 42 (Not sure what it is, but this light is not on normally, only in diagnostic mode)

    I reset the codes and they all were removed. The brakes seemed to function normally but the lights and softness in the pedal were back by the time I got to the end of the driveway.

    I also checked the 12v optima battery that was installed about 2 years ago, here is what it tested at:

    Car off: ---> 12.4v after sitting 24 hours, after the car was moved and turned off again it came in at 11.4v
    Car on: ---> 14.4v
    Car off: ---> Immediately dropped to around 12v and continued to fall

    Battery is now being charged so that I can at least rule out problems arising from low voltage.

    If anyone has any information or things that I can try please let me know. If there is additional information that would be helpful but I did not include please let me know.
     
    #1 Lynard55, Mar 7, 2020
    Last edited: Mar 7, 2020
  2. ChapmanF

    ChapmanF Senior Member

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    Ya gotta look these codes up in the right tables in the repair manual; the different lights blink codes from different subsystems.

    The ABS light blinked the 33 and 34. Those seem to both be issues with the speed sensors at the back of the car. Possibly wiring maybe, something common to both sensors?

    The VSC light blinked 43, and you look that up in the VSC codes table, and yes, it means "hey, did you hear you've got ABS codes?"

    The (!) light blinked 36, and you look that up in the ECB codes table, and that one turns out to also mean "hey, did you hear you've got ABS codes?" (The "foreign object" business came from looking up the code in the wrong table.)

    What did the light look like that was blinking this? Could you find it on a diagram of the dash lights? I'm not sure there is a power steering light in there....
     
  3. Lynard55

    Lynard55 New Member

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    First of all thanks so much for your reply, I have seen your previous posts many times already in researching the issues I’m currently experiencing. It is great that you are willing to help myself and others out.

    The light that came on during diagnostics looks like the attached image, of course on a black background in reality.

    I drove the car again after resetting the error codes. About 10 seconds in the error codes came back and braking and charging through braking is limited. I drove a few minutes and the lights turned off for the rest of the 10 minute trip.

    I waited an hour and the same thing happened. Error codes came on before I left the driveway, but turned off again with full braking restored a few minutes later.

    Is it possible that the battery voltage is dropping when I first put the battery under a load causing the error codes to flash before the alternator charges the battery back to 14v and then they go away? Not sure myself, any guidance is very much appreciated.
     

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  4. GrGramps

    GrGramps Active Member

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    You "filled the front tires". Is there much difference in the pressure between the front and rear tires?
     
  5. Lynard55

    Lynard55 New Member

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    First of all thanks so much for your reply, I have seen your previous posts many times already in researching the issues I’m currently experiencing. It is great that you are willing to help myself and others out.

    The light that came on during diagnostics looks like a steering wheel with an exclamation point next to it. I tried posting a picture but it requires moderator approval.

    I drove the car again after resetting the error codes. About 10 seconds in the error codes came back and braking and charging through braking was limited. I drove a few minutes and the lights turned off for the rest of the 10 minute trip.

    I waited an hour and the same thing happened. Error codes came on before I left the driveway, but turned off again with full braking restored a few minutes later.

    Is it possible that the battery voltage is dropping when I first put the battery under a load causing the error codes to flash before the alternator charges the battery back to 14v and then they go away? Not sure myself, any guidance is very much appreciated.

    Tire pressure was 33 psi in the front and 28 in the rear, I just brought the rear back up to 33.
     
  6. ChapmanF

    ChapmanF Senior Member

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    My mistake, that's the power steering light all right. I see it on page 498 of the owner's manual.

    I'm not finding blink codes for it though. That doesn't mean it hasn't got any (obviously). My Gen 1 had steering blink codes and they were in the repair manual. Most of the ECUs did at one time, and many still do, but for some the codes aren't given in the manual any more, so you just have to get the full five-character code with a reader to see what it is trying to tell you.

    In the old days, some of the ECUs had blink codes that were just the two last digits of the DTC, but the 2010 steering DTCs are mostly C15xx and there isn't any C1542 that I can see.

    So I'm drawing a blank on that one. I would get some access to Techstream and ask it for the full story.

    I am not one of the enthusiasts of the 'low battery voltage explains everything as computers making up random codes' theory; I'd be especially skeptical of it if the computers keep coming back around to exactly the same 'random' codes. Chances are it's trying to tell you something close to what it looks like it's trying to tell you.
     
  7. pjksr02

    pjksr02 Active Member

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    It's not unusual for a rear speed sensor to go bad. Sometimes these loosen up, even. Have you inspected them?

    What may be unusual is getting both rear codes at the same time. There's no sign of damage to the wiring, either in the back, or near the ECU, is there? No accident history? 20190924_102130.jpg
     
    Raytheeagle likes this.
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