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Will not start, then it did.

Discussion in 'Gen 2 Prius Technical Discussion' started by Blackwlf, Sep 1, 2009.

  1. Blackwlf

    Blackwlf Junior Member

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    My parents have a 2008 Prius. My mother went to start it, put her foot on the brake and hit Power. All of the dash lights lit up and flashed for a couple of seconds, then went dark. She pressed the e-brake, released it, and tried Power again. Nothing. She stepped out of the car, taking the key with her for about 30 seconds, then returned, pressed the brake, hit power and this time, it started. I am wondering if anyone else has had this problem. If so, what caused it? My thinking is that maybe the 12v battery got too low. That would not explain the fact that it did eventually start. I am not sure, I was thumbing through the manual while all this was going on, trying to find the troubleshooting section. I figure these things are closer to computers than cars, so I should be able to find a troubleshooting guide.
     
  2. jdenenberg

    jdenenberg EE Professor

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    Your guess about the 12v battery sounds right. Check that the voltage is more than 12v when the car is off and then doesn't drop too much when you turn on lights in ACC mode (press power once without brake). The voltage should rise to 13.8v when the Prius is in "Ready" mode.

    If the 12v battery is no longer holding a charge, get a new one.

    JeffD
     
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  3. qbee42

    qbee42 My other car is a boat

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    12V battery or keyfob battery. Either one could be a problem. If she has this trouble again, have her insert the fob in the dash slot. If that works, the fob is the culprit.

    Tom
     
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  4. richard schumacher

    richard schumacher shortbus driver

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  5. Sandy

    Sandy Hippi Chick

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    Mine was the 12V had it replaced and all is all good
     
  6. GaryGarland

    GaryGarland New Member

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    FWIW my guess would be the 12v contact is maybe corroded? It seems a bit early to me for the 12v battery to die already (unless you habitually left headlights on or otherwise drained it) - I don't know why the dash would start and then stop if it was the fob - i'd imagine it simply wouldn't start.
    I've previously posted queries and received responses - unless i'm mistaken the 12v battery essentially powers up the computers, and then the real workload comes from the traction battery - so my armchair diagnosis is the 12v wasn't powering up the computers because of a voltage issue - either the battery was deadish or the wires were - my .02 and worth exactly half of that.
     
  7. V8Cobrakid

    V8Cobrakid Green Handyman

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    as others have said... 12v battery. a fob battery would either work or not... it wouldn't give you a half boot. at first i was thinking cell interfearance.. but that wouldn't give you a half boot... so 12v battery is kinda the only thing.

    the connections really don't corrode as they really don't ever pull that much power through them. in a traditional car, the battery is a buffer for lots of electricity being pulled though it. (not so with the prius)
     
  8. richard schumacher

    richard schumacher shortbus driver

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    Reports of this are uncommon but the battery terminals and the negative cable connection to the car body can corrode enough to cause trouble. It's worth a look before replacing the battery.