08 with vsc, red brake light, car with exclamation point light

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by 08priusowner145, Dec 4, 2016.

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  1. 08priusowner145

    08priusowner145 Junior Member

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    Vehicle:
    2008 Prius
    Model:
    Two
    100k. I have an intermittent condition where the vsc, red brake light, car with an exclamation point light all come on occasionally. There is no notable difference in brake performance and if I shut off and restart the car just once, the lights are off again. This happens unpredictably and anywhere between one day apart or 4 days apart, and I drive 100 miles a day. I can only pull codes when the lights are currently on. They are:
    C1241-low or high power supply voltage
    C1249-open circuit in stop light switch
    C1378-capacitor communication malfunction
    Can anyone tell me what this is? I don't want to pay a dealer to drive my car forever to recreate the condition and/or have them just throw parts at it endlessly. I would like to fix this the first time. I used to be a mechanic but have limited knowledge of Prius vehicles.
     
    #1 08priusowner145, Dec 4, 2016
  2. valde3

    valde3 Senior Member

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    C1249 – You probably just need new brake light switch. It’s at the brake pedal. Shouldn’t be expensive or hard to replace.
    C1249 – Detailed code or other freeze frame information may help to diagnose this.
    C1378 – Detailed code or other freeze frame information may help to diagnose this.

    Mini-VCI would get that information for you if you want to be able to read codes yourself. Mini VCI is cheap and good tool and it’s also needed for some work on Prius anyways.

    Both C1249 and C1378 are related to 12V system. I would first just check the 12V battery. Is it fully charged? Can it supply current? Check connections on battery posts. Check all connectors on battery+ and capacitor (located right next to 12V battery). Also check the connection on battery negative cable at body side (both ring terminal to body and ring terminal to cable).
     
    #2 valde3, Dec 4, 2016
  3. Neohybrid

    Neohybrid Not-so-junior member

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    Location:
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    Still running the original 12-volt battery?

    I had similar "warnings" on the 08. I noticed it more when the weather started to get colder and the car was sitting outside overnight (usually in the heated garage). About a year ago I would get a long beep (like unlocking the doors) when I shut the car down. It was so infrequent I ignored it except for changing the FOB batteries - I thought that fix it. Then I started getting intermittent lights coming on (VSC, red triangle) and occasionally the MFD would display "put the car in park" when trying to start. It always disappeared after I turned the power off and then back on. Several threads led me down the path of replacing the 12-volt battery. After checking it through the diagnostics and confirming that it was weak I replaced it. The car just turned 92,000 miles. No more warning lights! And I may be crazy, but my gas mileage has improved.
     
    #3 Neohybrid, Dec 9, 2016
  4. andrewclaus

    andrewclaus Active Member

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    It's not unusual for a new 12V battery to increase gas mileage slightly. An old battery takes work from the engine to try to keep it charged.
     
    #4 andrewclaus, Dec 9, 2016
  5. JC91006

    JC91006 Senior Member

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    Anytime intermittent lights come and go, check all your cars fluid levels first
     
    #5 JC91006, Dec 9, 2016
  6. 08priusowner145

    08priusowner145 Junior Member

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    Does it make any difference that all this started happening while going down a section of street with a lot of potholes?
     
    #6 08priusowner145, Dec 10, 2016
  7. valde3

    valde3 Senior Member

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    Might give even more reason to check the stuff that I mentioned on the bottom of my previous post.

     
    #7 valde3, Dec 10, 2016
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