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No READY LIGHT, car can't start!

Discussion in 'Gen 2 Prius Technical Discussion' started by Dxta, Oct 19, 2018.

  1. Dxta

    Dxta Senior Member

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    Hi people! I was called by a client of mine today, to come check out a Prius 09, with about 75000miles that could nor start.
    The ready light, was not coming on the dashboard.
    According to the client, he barely drives the car, and when he tried driving it last week, from his compound, the the ready light came on the dashboard, and during his exit from the compound's gate, the vehicle suddenly stalled.
    He disconnected the 12V battery, and reconnected it, the ready light didn't come on.

    ME:
    1.Got there, tested the 12V battery. Was 11...volts, and was the original battery that came with the car.
    2. Tested all the fuses at the fusebox at the hood, and the driver side kick panel. They all checked OK.
    Checked the relays too.
    3. Opened up the hybrid battery pack, to inspect the contactor relay assemblies.
    I'm planning to get another assembly relay contactor to swapped it in there, and see what happens.
    4. Checked the SOC using tech stream, got 55.0%.
    That tells me the pack has got no issues.

    YOU!:
    1. What do you think could be the problem?


    PS: .
    1.I'm suspecting maybe the HV ECU, isn't sending out the normal 12V to the HV contactor assembly relays, in order to give them the go ahead to feed high voltage to the inverter assembly (that's y no ready light?).
    2. No codes retrieved from the vehicle; no check hybrid system and check engine lights on dashboards.
     
  2. Skibob

    Skibob Senior Member

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    Isn’t 11 volts on the 12 v kinda low?
     
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  3. brdmb

    brdmb Junior Member

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    Did you try jumping the 12v? Be careful as you do this, as always. 11v might not be enough to get the computers to boot up? They have to be booted before hv contactor will close

    Posted via the PriusChat mobile app.
     
  4. bisco

    bisco cookie crumbler

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    yes, this ignoring the 12v is perplexing, are we missing some info?
     
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  5. Dxta

    Dxta Senior Member

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    Got a replacement battery (12v) that read 12v, still no ready light.
     
  6. bisco

    bisco cookie crumbler

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    still too low? a new battery should be 12.8 - 13 volts, but may not be your problem.

    do you have rodent issues there?

    what about the fob battery?
     
  7. TMR-JWAP

    TMR-JWAP Senior Member

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    With foot off the brake pedal, will pressing the power button allow the car to go to acc mode or ignition-on mode?

    Also agree with previous posts that the 12v is sketchy at best. If unable or unwilling to replace it, I would at least hook a jumper pack to it or charger while trying to troubleshoot.

    Have you tried inserting the fob into the slot to see if it will go ready?

    Can you post a photo or video of the dash when trying to power up?
     
    #7 TMR-JWAP, Oct 19, 2018
    Last edited: Oct 19, 2018
  8. Dxta

    Dxta Senior Member

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    No one ignored the 12v battery. I go
    1. The ignition comes to power mode, when I'm not pressing brake.
    2. I brought a fresh aux battery from another car, still the same thing happened.
    3. I have not tried inserting the fob key into the slot.
     
  9. The Electric Me

    The Electric Me Go Speed Go!

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    So this has all manifested since the vehicle evidently stalled?
    Did the Client simply try restarting it after it stalled before disconnecting the 12V battery?
    Did the vehicle throw any codes or warning lights when it stalled?

    I'm hoping no damage was done in disconnecting and reconnecting the battery.

    Also, he barely drives the car?
    Does this mean it sits for long periods? Had it been sitting for a long period?

    Then if you answer all this?
    I really have no idea....
     
  10. Skibob

    Skibob Senior Member

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    Have you checked the voltage at the jump points under the hood? Just to rule out a bad battery cable.
     
  11. Dxta

    Dxta Senior Member

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    No any sort of codes, and no check hybrid system and check engine light that came on.
    You for no idea, OK, thanks
     
    #11 Dxta, Oct 19, 2018
    Last edited: Oct 19, 2018
  12. Dxta

    Dxta Senior Member

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    Even with the new 12v battery, the HV relay contactor's don't even click, when you try putting it in ready.
     
  13. Dxta

    Dxta Senior Member

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    Can a weak dead battery in the key fob caused the ready light not to come on?
     
  14. brdmb

    brdmb Junior Member

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    It would usually make the key light flash in the error lights section when you press the power button, and the ready does not come on. Putting the fob in the fob slot eliminates that as a possible problem.

    Posted via the PriusChat mobile app.
     
  15. bisco

    bisco cookie crumbler

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  16. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    Make sure the battery negative connection to the chassis is in good condition.
     
  17. bisco

    bisco cookie crumbler

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    check the brake light switch
     
  18. TMR-JWAP

    TMR-JWAP Senior Member

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    check the brake light switch

    X2. If the car will go to acc and to ig-on each time you press the power button with no foot on brake, the car is recognizing the key. Foot on brake but not going to ready would lead me to believe there is possibly an interlock missing for that step. The brake switch is part of that, but I'm not certain what else may be required. I know it's been discussed on the forum previously, so it should be in here somewhere. Not sure how that relates to the engine stalling in the original episode, unless there is a common electrical glitch that hasn't been discovered yet. Is 12v power present on the relay control wires when trying to go to ready?

    Another thing to think about is the HV battery state of charge. I know you said you checked it with techstream and it showed 55%, but that is probably not true. Your client disconnected the 12v battery. This would set the SOC back to a default value. If the car has been un-driven since that time, the computer has not had a chance to actually re-cal to the true SOC.

    There's been many times I've just hopped in my car and gotten out of my driveway and down the road a little bit before the engine kicked on for it's warm-up routine.
    Maybe, what he thought was a stall was just the engine never running, just trying to start and then giving up. Then all codes were reset when he disconnected the 12v?

    Maybe the shift lever or it's circuit failed or came unplugged?

    Throwing stuff at the wall until something sticks.....:)
     
    #18 TMR-JWAP, Oct 19, 2018
    Last edited: Oct 20, 2018
  19. Dxta

    Dxta Senior Member

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    Would try putting the fob
    Would try putting the fob closer to the fob slot and see what happens.
     
  20. Dxta

    Dxta Senior Member

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    Would check that out when I get to the car this week.