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Help! My 2007 Prius will not go to READY mode!

Discussion in 'Gen 2 Prius Technical Discussion' started by leemcgee, Jun 29, 2016.

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  1. leemcgee

    leemcgee Junior Member

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    I am unable to start my Prius. Brake pedal plus POWER button gives me 5 warning lights on the panel, shifter will only to to Park or Neutral, and most importantly no READY mode. I checked the 12v ACC battery in maintenance mode INFO three times headlight, and it shows 12.0V normally and 12.4V if on trickle charger.

    I reset the hybrid system Service Plug, pulled it out for 20 minutes then re-inserted, same problems.

    The problem first occured because I had a severe catalytic converter plug-up problem climbing a local hill, the car displayed its red triangle (!) warning, then stopped completely. The exhaust problem was noted by a local mechanic, NOT a hybrid mechanic. It would never power up to READY after that. I had the car towed home to investigate.

    My Gen 2 Prius has 420,000 miles on it. Possible problem source? Traction batteries have all been good up to this date, car was getting adequate gas mileage and driveability.

    Is there a reset method for this? Thank you, Lee McGee
     
    #1 leemcgee, Jun 29, 2016
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  2. S Keith

    S Keith Senior Member

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    Read the codes. options in my signature.
     
    #2 S Keith, Jun 29, 2016
  3. JC91006

    JC91006 Senior Member

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    1. check to make sure it's not low oil causing the warning lights and no power
    2. When you remove the orange plug on the hybrid battery, did you install it properly by sliding it downward to lock it in?
    3. Read codes as mentioned on previous post.
    4. 420,000 miles is a pretty good run.......even if you can't revive it.
     
    #3 JC91006, Jun 29, 2016
  4. leemcgee

    leemcgee Junior Member

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    #4 leemcgee, Jun 29, 2016
  5. leemcgee

    leemcgee Junior Member

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    It started! The key was to unhook the 12v battery negative terminal while doing the HV Service Plug reset. Once all hooked back up it started, thanks!

    So in general the fix to this problem is:

    1) unhook 12v battery
    2) take out then put back in HV service plug in rear of car.
    3) rehook 12v battery
     
    #5 leemcgee, Jun 29, 2016
  6. JC91006

    JC91006 Senior Member

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    sounds like if you turn it off, it might not turn on again. You didn't discover your problem, only reset to start.

    There's is no reason to do a hv battery reset....this doesn't do a thing
     
    #6 JC91006, Jun 29, 2016
  7. S Keith

    S Keith Senior Member

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    Please refer to post #2. You'll need to do it soon enough.
     
    #7 S Keith, Jun 29, 2016
  8. dolj

    dolj Senior Member

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    What, if anything, did you do to rectify the catalytic converter plug-up problem? You never said.

    As others have said, The "HV Plug Reset" will do nothing at all. It is not a real procedure. Not sure where you got the idea that it would achieve anything.

    Disconnecting the 12 V aux battery will reset most of the computers and clear most existing codes, which has resulted in your car appearing to now behave as normal. You have not really achieved anything in terms of "fixing" anything. Only removed the information that would have told you what was wrong. If you have indeed done nothing else but this procedure, you will have the the same codes come back and illuminate the dash lights.

    When they do, please read the codes. You will then have a better idea where to channel your energies.

    Options for reading codes in S Keith's signature above - click on "Reading Codes".
     
    #8 dolj, Jun 30, 2016
  9. leemcgee

    leemcgee Junior Member

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    #9 leemcgee, Jul 20, 2016
  10. leemcgee

    leemcgee Junior Member

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    Hi thanks for your post, the car has been sitting for a few weeks now, and the 12v battery goes dead, which it was this morning.

    Resetting the HV service plug plus pulling the 12v battery ground then resetting it was absolutely necessary to get my READY light going again.

    In the intervening time I bought myself a code reader, and finally was able to read some codes. It turns out that the root cause problem is P2238, "O2 sens positive current low bank1 sens1". And I learned from this site that bank1 sens1 is the upstream Air/Fuel sensor, which if not working causes the engine ECM to run very rich, the very rich running might have melted the cat, have not looked at the damage yet.

    Possible Causes per this site P2238 notes are:

    Faulty EFI relay
    Fauly Air/Fuel Sensor Bank 1
    Air/Fuel Sensor Bank 1 harness is open or shorted
    Air/Fuel Sensor Bank 1 circuit poor electrical connection
    ECM

    OK. So last night I removed the four-relay C unit which had the EFI relay in it to check the wiring etc, left it out overnight, put the C module back in the car this morning and NO COMBINATION METER DASH LIGHTS when pushing power button at all. The 12v battery was dead, no charge. I am charging the 12v battery, but still No READY, NOTHING when I press the POWER button.

    Does anybody know what is wrong what I would need to reset? Thanks Lee McGee
     
    #10 leemcgee, Jul 20, 2016
  11. JC91006

    JC91006 Senior Member

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    1st thing to do is to change out the 12v battery. After you do that, then you'll have a reliable power source to do other diagnostics. The A/F sensor will not prevent the car from starting, there's other issues with your car.

    Whenever you reset the car by letting the 12v battery die, all your codes disappear. You'll never be able to figure out your problem until you get a reliable 12v battery.
     
    #11 JC91006, Jul 20, 2016
  12. leemcgee

    leemcgee Junior Member

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    Thanks! The 12v battery certainly was reliable enough up until today at least, was giving the code readouts, starting the car etc. Do I need to let the 12v battery charge for a while until my POWER button begins to work again?

    My main concern was did I do something to that EFI relay, removing then replacing that C module, to cause the Prius POWER button to not work?

    Thanks again! Lee McGee
     
    #12 leemcgee, Jul 20, 2016
  13. JC91006

    JC91006 Senior Member

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    1. Make sure 12v is charged to full, 12.8v or above....replacement may be necessary
    2. Get a minivci cable to read the codes, what you have is most likely not able to read all the Prius codes
    3. Use the key slot in the car and try to start, don't use the SKS feature to do it.

    Your car most likely has several problems. Until you get a proper code reader that can read Prius codes, you will not be able to diagnose the electronic side of the car......basic readers only read the engine codes, that's why you have found the a/f sensor error only.
     
    #13 JC91006, Jul 20, 2016
  14. leemcgee

    leemcgee Junior Member

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    #14 leemcgee, Jul 20, 2016
  15. leemcgee

    leemcgee Junior Member

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    12.8 volts or above is interesting. Since when does a 12v battery need 12.8 or above?
     
    #15 leemcgee, Jul 20, 2016
  16. JC91006

    JC91006 Senior Member

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    You need to read some more about 12v batteries.

    A fully charged AGM battery (the prius battery) will measure 13.1 volts when fully charged. 12v is really considered DRAINED, if that's what your battery is showing. The Prius does not require much from the 12v battery, it only starts the electronics. But if the 12v is low, all the electronics will not function properly and you can get a lot of errors.

    Since you are diagnosing your car, which seems to have more than 1 issue, you would need a very good 12v battery to begin. Once the battery drains and you lose your DTC codes, you will have to start all over again..
     
    #16 JC91006, Jul 20, 2016
    Last edited: Jul 20, 2016
  17. leemcgee

    leemcgee Junior Member

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    Thanks! My 12v battery show 13.57 volts right now, measuring with voltmeter across the battery terminals, yet I still get NOTHING from the POWER BUTTON.
     
    #17 leemcgee, Jul 20, 2016
  18. bisco

    bisco cookie crumbler

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    you need to measure the voltage with the car off and after the car has been off for at least a few hours. this is the cold standing voltage. anything under 12.4 is unacceptable.
     
    #18 bisco, Jul 20, 2016
  19. JC91006

    JC91006 Senior Member

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    Something is wrong if you are getting 13.57v , the agm battery should be charged with about a 4 amp charger, any more can damage it

    You still should be able to get response on your car
     
    #19 JC91006, Jul 20, 2016
  20. leemcgee

    leemcgee Junior Member

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    Thank you JC and Bisco. I just measured the 12v battery this morning and it is at 12.33 volts. I see all the usual 12v battery indications on the dash, such as it knows a door is opened, it knows when my smart key is in the car, etc.

    My problem is that the POWER BUTTON does NOTHING. I think we are losing sight of what the real problem is here. Any knowledge to share on this?

    Thanks!
     
    #20 leemcgee, Jul 21, 2016
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