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12v voltage / symptoms

Discussion in 'Gen 3 Prius Main Forum' started by nicoj36, Nov 11, 2023.

  1. nicoj36

    nicoj36 Active Member

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    Vehicle:
    2010 Prius
    Model:
    II
    I got the ABS, VSC, brake lights on the dash the other day while driving. I parked the car, turned it off and checked under the car to see if anything is stuck by the brakes, sensors, abs, etc. Clean and clear. Checked under the hood fluids/fuses good. I started the car back on and the lights went away after 5 mins of driving.

    When I got home I plugged in my OBD to check for codes and it said C1467 Rear LH speed sensor. Also, my OBD scanner also has a 12v monitor and I noticed that my 12v voltage was at 11.8 while I was scanning the car with it on the on position (press on twice) not running/started.

    Is that voltage normal or pretty low while its in the on position getting scanned with OBD? Also is it possible that the ABS/VSC/brake lights and speed-sensor code was just one of the weird symptoms of a bad 12v battery? I know I've read in the past that bad-12vs on priuses can show a lot of different symptoms.
     
    #1 nicoj36, Nov 11, 2023
  2. ASRDogman

    ASRDogman Senior Member

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    11.8 is very low. How long ws it after you stopped?
    While the car is "ready", you should have over 13 volts.
    But a low voltage 12v battery creates a lot of issues.

    You should charge the battery at 4amps or less overnight, or 8-12 hours.
    Wait about an hour after removing the charger then check it.
     
    #2 ASRDogman, Nov 11, 2023
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    While really low voltage to various ecu's can cause problems, the 12V battery is treated like the "boogie man". You have to have maybe 9V or less for some seconds before the electronics get flakey.

    Your ABS code set while the car was ready and the DC DC converter was supplying 14V to everything.

    It's not a bad idea to properly charge and load test your 12V battery. However, just follow the service manual diagnostic procedure for the wheel speed sensor code.

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Nov 11, 2023
  4. bisco

    bisco cookie crumbler

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    if you pressed the power button twice (no foot on brake) the car is not made ready, and there is a load on the battery. 11.8 is probably considered within normal range. how old is it?
     
    #4 bisco, Nov 11, 2023
    CR94 and kc410 like this.
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