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New owner - 12v issues, one start only.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by HLPrius04, Jul 15, 2021.

  1. HLPrius04

    HLPrius04 New Member

    Joined:
    Jul 11, 2021
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    Location:
    Arkansas
    Vehicle:
    2004 Prius
    Model:
    Two
    New owner here (5 days) Long Post Warning
    2004 model.

    first, I’m ordering mini VCI today as well as BT OBD2 scanner (I have a WiFi model)

    I have no codes to share today, just observations

    Im searching and reading similar topics as fast as time allows. Still hoping you guys with the experience can put me right onto some checks/fixes based upon my current symptoms

    Bought Saturday from an individual with no precious issues other than replaced the 12v battery in December. It test drove great, drove it home 3 hours. Next day my son backed out of his drive way and it dies.
    Won’t go into ready mode, have all the warning lights on, including big scary red triangle and the MFD displaying the red car icon with exclamation point.

    I learned about the diagnostic screen and found the 12V battery at about 11.4 V
    Took it out and charged it. It was at 12.8 at my house across town. By the time I installed it I had a reading of 12.5. Car would not go into ready, but we could get it into N to move it back to where it had been parked. battery had dropped to about 11.5 by the time we quit fooling with it.
    I replaced the battery with another new one (last one was 8 mo old).
    Car went into READY and off we go. A few hours later when my son is leaving my house, it’s dead again. I charge the battery with a new 4A charger with AGM mode. Reinstall it, READY mode, take a test drive with diagnostic screen up and I leave with the battery at 13.7 (iirc) but watch it drop to 13.0 upon braking (only 2nd time applying the brake on this test) about halfway through my 4 mile test run.
    I get back and shut it off and same problem, won’t go back to READY. I think the battery was showing about 11.5 on the diagnostic screen, but was measuring 12.0 at the battery as I recall. I charge the battery again and reinstall this morning. I get READY mode and Engine starts.
    I go ahead and checked the Inverter coolant and see it circulating. I didn’t have time to drive it or anything.
    So seems like I’m not maintaining 12v + volts, or more, whatever is required.
    I did notice I have “doors open” icon indicating both front doors are open. This is even when the key is out of the car. What’s that about?
    What can I check while I wait for better diagnostic tools to arrive?
     
    #1 HLPrius04, Jul 15, 2021
  2. RobertK

    RobertK Member

    Joined:
    Sep 9, 2007
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    Location:
    Norfolk, VA
    Vehicle:
    2007 Prius
    Model:
    N/A
    The icon indicates that you have one or more doors or the hatch is open. It does not tell you which one is open. Sounds like you might have a bad door switch or some kind of short in the interior lighting. Do the interior lights turn on and off when you open or close a door? There is a shutoff delay if the car is not running.

    I'd charge the battery again and check each of the door/hatch switches and make sure that all of the interior bulbs are working properly. The car should not lock with the key fob if it thinks a door is open.
     
    #2 RobertK, Jul 15, 2021
  3. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
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    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Agree its likely to be parasitic draw but not if it fails to go into Ready within minutes of a shutdown. If it is immediately failing after a drive, it would seem the car is not charging the battery. However seeing the voltage rise after a Ready is normally a good sign of charging. A well charged 12v battery will result in reduced charging voltage as you drive.

    To measure parasitic draw see this post from earlier today.
    12V Battery Not Charging | PriusChat
     
    #3 rjparker, Jul 15, 2021
  4. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
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    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    I believe the 12V battery is a red herring. The voltages you report would not cause the (non) drivability issues you report.

    We need to see the codes, so hopefully, your scan tools arrive soon and we can get that information.
     
    #4 dolj, Jul 17, 2021
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