Front defroster causes red triangle of death

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by SFPriusonr, Jan 18, 2018.

  1. SFPriusonr

    SFPriusonr New Member

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    When I use my front defroster, not long after, I get the red triangle of death. The steering wheel climate controls used to be yielding the wrong outcomes: push front defrost and air recirculate would light up, push rear defrost and front defrost would light up, now none of the 3 buttons respond to pushing. I think there is a short in the circuit that drains the 12 volt starter battery which yields the red triangle and check engine christmas tree.
    Has anyone had this experience? If so, how was it resolved?
     
  2. edthefox5

    edthefox5 Senior Member

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    Replace the 12 volt battery. Not charge it replace it.
     
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  3. Prodigyplace

    Prodigyplace Senior Member

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    With a weak 12 volt battery the computers get confused.
    By the way, it does not start the engine. It just boots up the computers.
    The large traction battery uses MG1 to start the engine.
     
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  4. WilDavis

    WilDavis Senior Member

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    I'd be curious to know if it was throwing any codes, however a bad AuxBattery (12V) can cover a multiple of sins! Good luck, and welcome to PriusChat! (…you've come to the right place, but be warned! :eek: PriusChat can be addictive! :rolleyes:;))
     
  5. bisco

    bisco cookie crumbler

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    welcome!
    a parasitic drain on the 12v can be difficult to find. you need a degree in electronic testing equipment and schematic reading.
    are you prepared to tackle it, or looking for a qualified shoppe?
     
  6. dolj

    dolj Senior Member

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    Sounds like your clock-spring cable (aka spiral cable) is broken. Purchase a genuine Toyota replacement for the best price you can find. Be very wary of cheap clones on eBay and Amazon. Buy only from a genuine Toyota user on those sites. A reasonable price for genuine OEM is $90-$130.

    Don't take too much notice of all the 12 V alarmist and waste too much time on the 12 V battery other than ensure it is fully charged and can hold a charge.

    Even better, if the master caution light (MCL) is on, there should be codes. Read them and report back here with them. Then we can all stop guessing.
     
    #6 dolj, Jan 18, 2018
    Last edited: Jan 18, 2018
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  7. SFPriusonr

    SFPriusonr New Member

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    I did replace it... ( the 12 volt battery) it is doing the same thing again, but only when I use the front defroster, and since the only mode that operates it is the dash screen, I just don't use the front defrost. And, magically, the red triangle of death disappears. However, when it rains, the window fogs up and it requires open windows that balance fog clearing with interior soaking from the rain.
    I hear talk of the coil spring and have seen another discussion of it being the source of this problem, or at least the location of it on the steering column (steering wheel).
    I agree, trying to debug electrical circuits is a fool's errand, or a cost-prohibitive Toyota shop visit.
    If I follow the YouTube video of the replacement of the right side circle of controls holding the defrost button, I just don't know what I would be looking for other than an obvious break in some wire, or default to the assumption of a bad switch that in its failure is shorting.
    Sounds like the Toyota service route is my only real opportunity to resolve this. Though, frankly, I don't trust them to be efficient or reasonable... or actually solve the problem, having understood it.
     
    #7 SFPriusonr, Feb 16, 2018
    Last edited: Feb 16, 2018
  8. Prodigyplace

    Prodigyplace Senior Member

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    When 12 12 volt battery is good, if the steering controls are not behaving properly that usually points to the "clockspring" wiring connecting those controls, and the airbag, to the rest of the car's systems.
    People replacing that part have generally had the most success with a new or used Toyota part rather than an aftermarket one. Since the airbag is potentially impacted too, this could be a safety concern.
     
  9. SFPriusonr

    SFPriusonr New Member

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    By the way, thanks for the warm welcome. Already, with the answers and such selfless contributions, I feel at home.
     
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