won't start, no lights on dash, all batteries charged

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Gilberty, May 9, 2018.

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  1. Gilberty

    Gilberty New Member

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    2007 Prius, no problems until last week, would not start, no lights on dash except door light. towed it in to dealer, sat for 2 days, started fine, no trouble codes. sent home, same problem next day, sat at home 2 days still would not start, towed in again. Toyota service says they can't figure it out, both 12 volt and hybrid batteries fully charged, no trouble codes. It starts when at the dealer.Thanks for any help.
     
    #1 Gilberty, May 9, 2018
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The next time that the car does not start, measure voltage at the dedicated jumpstart terminal located in the main relay/fuse box next to the inverter. Use a front strut top mount nut as the ground connection for your digital multimeter. I think you will find the voltage is too low, and if you find this is the case, then measure the voltage at the 12V battery itself.

    If you find the voltage at the battery is also low, then replace the 12V battery, regardless of any prior claims that the battery is charged. If you find the voltage at the battery is OK, then look for a loose or failing battery cable. Especially, check the negative cable where it bolts to the body.

    Recall that a fully-charged AGM battery, open-circuit, should measure 13.0V. A discharged AGM battery will measure 12.0V. See how your measurements relate to this range.
     
    #2 Patrick Wong, May 10, 2018
    Last edited: May 10, 2018
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  3. edthefox5

    edthefox5 Senior Member

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    My pretty new 12 volt battery lives at 12.6 volts with car off.

    Do what pat says but do this also. With car off turn on the headlights in high beam and then measure
    The voltage at the front jump points again. I think you will find you have a bad 12 volt battery.

    I think the car is also throwing an instantaneous red master caution alarm on the dash during start up and your not seeing it. It’s a big red triangle. That’s the car warning you the battery is bad.

    The reason we want you to measure at the front jump points is that’s where the battery voltage is used.
    The battery had to go through many connections and a big fuse in the trunk to get to that front fuse box.
    Doesn’t matter that battery measures in the trunk. It only matters what it measures where it gets to where it’s used.
     
    #3 edthefox5, May 10, 2018
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  4. Gilberty

    Gilberty New Member

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    well it seemed like it was hopeless, batteries fully charged. it seemed like it only happened after a rain. Th dealer said they could only figure it out if it did not start and it always started for them. I took it to Auto Tech Solutions in Chatham NY and they patiently searched the system. turned out if was a problem with the power button having a break in the wiring so it only intermittently got power. Auto Tech rewired it and now it starts. Thanks Auto Tech 518-392-2500
     
    #4 Gilberty, May 30, 2018
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  5. Andyprius1

    Andyprius1 Senior Member

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    Great!
     
    #5 Andyprius1, Jun 10, 2018
  6. bisco

    bisco cookie crumbler

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    how many miles on her?
     
    #6 bisco, Jun 10, 2018
  7. Mygirlsprius21

    Mygirlsprius21 New Member

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    Please help !!!! | PriusChat
     
    #7 Mygirlsprius21, Dec 15, 2021
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