07 Prius Master Warning Light w VCS, CE, & Brake System

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by cigarette, Feb 16, 2021.

  1. cigarette

    cigarette New Member

    Joined:
    Feb 16, 2021
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    Location:
    Indiana
    Vehicle:
    2007 Prius
    Model:
    Three
    Hello, I have a 2007 Prius that just recently started throwing the lights mentioned above. Earlier this evening, about three hours ago, I passed 142k miles on the way to my friends house about 15 miles from where I live. I was there for about an hour, and when I started the car to leave the all of those lights came on for the first time. I turned the car back off to research what was happening and after a minute started it again. Since my friend doesn't have a car and I had no other option I drove it home. It drove fine even on the highway, no issues going into drive, no issues accelerating. I monitored the battery levels and noticed that while at times it would reach full rather quickly, it depleted just as fast. I went back out about a half hour ago to make sure I'd remembered which lights were on, and I also started and drove the car to the end of my culdesac with no problems. All Autozones and the like are closed, so I can't have the codes read until tomorrow.

    I've read it could be a multitude of things from the HV battery or 12V battery to low oil(although I don't think that's it). It's currently 18 degrees where I live and the car had been sitting for a few days, could this have had an effect? In the last few months Ive also noticed an issue with the fuel gauge being inaccurate. I read that this could have something to do with the HV battery, but I also know that it's a common issue in Prii.

    Any help, knowledge or words of wisdom are appreciated! Thanks!
     
  2. SFO

    SFO Senior Member

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    Location:
    Northern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    Welcome to PriusChat!!
    Find a toyota hybrid compatible OBD2 scanner and retrieve the DTCs (codes), then post them here for additional guidance. If you can't locate an appropriate device, we can recommend such. The best in class would be a 'mini-vci' cable (20 usd) and techstream.

    My WAG would be a failing HV battery, corroded ECU / sense harness, but knowing the codes will likely lead you in the right direction.

    Do you have some tools and a DIY attitude, or would you be looking to pay someone to diagnose and make the problem(s) go away?

    FYI : you're moderated until you've posted five (5) times, and here could be a lapse in your replies and responses.
     
    Raytheeagle likes this.
  3. cigarette

    cigarette New Member

    Joined:
    Feb 16, 2021
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    Location:
    Indiana
    Vehicle:
    2007 Prius
    Model:
    Three
    Hey, thanks for the quick response. I actually remember seeing your name in some of the threads I read haha.

    Most of my "mechanic" experience in the past has been with pretty simple vehicles outside of an Audi, but I'm certainly more knowledgable/willing to do it myself than the average person with no automotive background whatsoever haha. This is the first hybrid I've owned and I bought it a year ago, so outside of changing the oil I haven't had to do anything to it—especially with how little I've been driving due to the pandemic.

    Some of my friends that have worked in Toyota garages, unfortunately not on Prii, have told me in the past about how dangerous it can be to mess with battery stuff so I depending on what it is/difficulty I might be leaning towards taking it to a shop. That could have been exaggerated though.

    What would you imagine the costs might range from on a corroded ECU/sense harness if I took it to a shop? If I didn't, how difficult are those to fix? I know HV replacements are pricey, but if its something that's reasonably straightforward and safe then I'd consider doing it myself. Can't really take a $3k hit right now.

    Thanks again!
     
  4. ChapmanF

    ChapmanF Senior Member

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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Another vote for reading the trouble codes. The MWL is on because the HV ECU has some codes it wants you to know. The brake and skid lights are on because the skid ECU has heard that the HV ECU has codes it wants you to know.

    So those codes should get read. Until then, it's early to be stressing about what any of the numerous possible reasons it could be.
     
  5. SFO

    SFO Senior Member

    Joined:
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    Location:
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    Vehicle:
    2007 Prius
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    N/A
    Try scanning for the OBD2 codes (DTCs) at each of the auto part store chain locations that are nearby or within a reasonable distance, as each store may offer a different OBD2 scanning device, and not all scanner are toyota hybrid compatible. Don't let them clear the codes, though the OBD2 codes will likely return even if they did.

    Post all of the retrieved codes (DTCs) in this thread for further guidance and help.
     
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