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No READY Mode AGAIN!

Discussion in 'Gen 2 Prius Technical Discussion' started by leemcgee, Sep 12, 2016.

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  1. leemcgee

    leemcgee Junior Member

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    AGAIN! After over a month of driving the Prius, ready light every time, after using it for a 225 mile trip today, brought it home, I reset the DTC codes with my OBDII scanner (autel maxiscan) to turn off the check engine light (it had catalytic converter P0420 and P1121 a new one which I understand has to do with service bulletin and something called a coolant control value "stuck". Turned it off, then I hit the power button and guess what! No READY mode. Four lights,but transmission will not go into reverse or drive.

    Last time this was fixed by charging the12v battery enough to get a reasonable voltage, then reset the battery by unplugging ground in back of car. Should this work after a good charge this time? I noticed from my charger that the battery seemed low.

    By the way, I resolved the catalytic converter problem by scraping off a thin film of carbon (was either oil or too much gas), this got me down to reasonably good honeycomb, car has been running now with good gas mileage 48 mpg, not bad for 400,000 miles.

    So again my question, do we think I might get the READY light again after a good 12v battery charge?

    My 12v battery was down to 12.4 volts, not enough. So I tried a jump start from another car with the negative 12v terminal removed, I got 13.07 volts from this, still no READY light.

    I am at wits end. I have no idea how to start this Prius.

    Thanks all, you are the best!

    Lee
     
  2. bisco

    bisco cookie crumbler

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    try replacing the battery.
     
  3. fotomoto

    fotomoto Senior Member

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    Two things come to mind:

    1) Power switch may be going out.

    2) Brake sensor switch may be out of adjustment. Check and see how far you need to push the brake pedal before the brake lights come on.
     
  4. dolj

    dolj Senior Member

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    No, the 12 V battery is most likely not the problem.
    Who said? While 12.4 V indicates that the 12 V is low (a full OEM AGM battery will be in the region of 12.8-13.2 V) and should be charged anyway, just because it is low, it is not low enough to cause problems. Unless your battery is in such poor condition that it is dragged to under 10.5 V on the start up cycle. You can verify this easily enough by using a digital multimeter (DMM) to measure the voltage on the 12 V accessory socket (formerly known as the cigar light plug), and then firstly, put the car in IG-ON read the voltage; then secondly, try and make the car READY and watch the voltage as it goes through the boot-up. If it does drop significantly, then throw out that battery and buy a new one.
    Even if these codes were the only codes your car has, clearing them and doing nothing else is not fixing anything. This process is the same as thinking that you have fixed your mortgage default by throwing the default letter in the bin.

    Further, given the lights that you say are on, I would bet that your reader is not reading any of the codes set by Prius specific ECUs. You need to get a hybrid compatible reader (such as VxDiag with Techstream) or go to a place that can read all the code that are being set. Without doing this all anyone can do is make WAGs, which may get you blindly replacing perfectly serviceable parts.

    Next, having got the codes you need to follow Chap's (ChapmanF) opt dispensed advice and go to techinfo.toyota.com where you can access the new car features manual in conjunction with the all the information you need for each code in the factory repair manual. This can be accessed on an all you can eat basis for US$15 for 2 business days (can give you Fri, Sat, Sun and Mon, if you're clever) or US$75 for a month. Each code (and sub-code) has a specific diagnostic tree that can be followed to isolate where and what the fault is.

    Your other option is to take it to a suitable repair shop if this is all too much.
     
    #4 dolj, Sep 12, 2016
    Last edited: Sep 12, 2016
  5. leemcgee

    leemcgee Junior Member

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    Thank you very much bisco, fotomoto and especially dolj for your replies. I will check that battery voltage today, I agree with dolj however that this is likely not the battery, here is my reasoning:

    1) I did a test yesterday with the battery completely disconnected (negative ground terminal wire removed), and jump started the Prius from another car with perfectly good 13.07 volt battery. I still got NO READY light.

    2) The Prius lights up the panel with ALL warning lights when it gets this not ready condition, you see all the warning lights and the transmission will only go to neutral and park, no reverse or drive. But I see all warning lights even if I do the "no brake pedal' power on. Is this normal, or does this mean my brake pedal

    3) Climate control, air, doors, windows all work correctly and have power.

    I managed to eventually get a READY a couple months ago by disconnecting battery negative terminal and pulling the HV service plug, then reconnecting both after 10 minutes or more wait time, then starting with POWER.

    Thanks, planning to try a bit more today, will have more posts here I'm sure! Lee
     
  6. leemcgee

    leemcgee Junior Member

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    dolj, where do you find a suitable ground inside the passenger compartment for checking voltage at the accessory plug?
     
  7. leemcgee

    leemcgee Junior Member

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    On another thread in PriusChat, titled "inconsistent-start-fail.", I found this note:

    --
    The issue sounds like an intermittent electrical connection between the DC/DC converter (which is part of the inverter and produces power to feed the 12V bus when the Prius is READY) and the main relay/fuse box which is next to the inverter. The reason there are no error codes is because when 12V power is lost, the memory on most ECUs (other than skid control and SRS ECUs) is erased.

    Next time the issue happens, it sounds like if you wait for a while, the car might become READY again - since the dealer tech cannot locate the problem.
    --

    This indeed sounds like some kind of intermittent problem to me, I might be confusing correlation with cause. If I had a dollar for every time I've done that, I would have a lot of dollars by now.

    Is there a possibility that this could be some sort of electrical connection problem? A fuse somewhere? Is there a way to look at the DC/DC wiring? Thanks all -Lee
     
  8. dolj

    dolj Senior Member

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    The side of the socket will do.
     
  9. leemcgee

    leemcgee Junior Member

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    Thank you dolj. I got 11.3 volts before start, hit brake pedal and POWER, went to 11.03 volts and stayed there throughout getting into NO READY mode (all five warnings lit up on dash). No red triangle. No DTC codes.
     
  10. The Electric Me

    The Electric Me Go Speed Go!

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    You have a 2007 Prius with 400,000 miles on it.

    And it is routinely showing you codes for various problems.

    And your avenue to resolution seems to be homespun remedies.

    Don't mean to be snarky, but with 400,000 miles on it, and it telling you it has issues, it doesn't surprise me too much that your Prius is being uncooperative.

    Resetting codes, Charging dying batteries, and scrapping film off of 400,000 mile catalytic converters will only get you so far, for so long. Masking or delaying problems can cause things to snowball, and suddenly you can be at a point where you don't know what problem is causing what reality.

    You might be reaching the point of decision. Permanently solve some of these problems with full fledged replacement or repair, or simply expect that you will continually be in a cycle of not being able to rely on your Prius.

    400,000 miles, is a point where most vehicles need full fledged maintenance if they are to be expected to be anything near reliable going forward.
     
  11. leemcgee

    leemcgee Junior Member

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    I am trying to solve a no ready light issue here.
     
  12. leemcgee

    leemcgee Junior Member

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    Here, from a hybrid specialist in my local area (Berkeley, CA), is a good diagnosis checklist:

    So from a distance, there isn't much we can do for you aside from describe what the Prius is thinking while it attempts to READY.

    1. First, it checks whether the ON button is pushed.
    2. If so, is the brake also being pressed? -- check that your brake lights light up, otherwise there may be a problem with the stop light circuit
    3. If the brake is pressed, then it asks the TCM about the current position of the parking pawl. -- a bad 12v battery will cause TCM to "forget" whether the car is in park.
    4. If it still cannot ready, then the MWI will illuminate (big red triangle) with information codes pertaining to the high voltage (HV) side of things required in the next steps. Sometimes there is no power to the MG1 to crank; sometimes the engine is cranked properly, but it does not run.
    5. If the engine is cranked but does not run, it can be caused by anything that might cause a normal engine to fail to start
    6. If the engine cannot be cranked, it could be a discharged HV battery or similar power supply/distribution malfunction
    7. If the HV battery is discharged, the vehicle will not attempt to crank even if you attempt to trick it by disconnecting power. The 2001-2003 Prius used to let users attempt to crank following a forced restart, but consumers would completely discharge their HV batteries to 0% SOC and cause all sorts of problems. Now the 2004-2009 protects you from yourself!

    I was going through the checklist and I think that I may have FOUND THE PROBLEM! The brake light switch (stop light circuit) is not working #2. Apparently the startup uses the brake light switch not the brake position sensor. I have no brake lights.

    Thank you all for all of your help! Lee
     
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  13. dolj

    dolj Senior Member

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    This does not look good, and I'm assuming you have tried to charge the 12 V battery in the past, and also given that you acknowledge #3 in your subsequent post:
    you would do well to bite the bullet and just replace the 12 V battery, I gather you have had a good run out of this one.

    You also need to address your coolant control valve and catalytic converter issues, in addition to the brake switch.

    After that, you can clear all codes and then see what codes come back.

    Like I said before, your code reader is not up for the job - if there are lights on you should be reading codes.

    Good luck with getting her all fixed up.
     
  14. leemcgee

    leemcgee Junior Member

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    Thanks dolj, there were lights on but that is what the Prius does when you don't have READY mode, there are no issues with those lights at all.

    I found the problem! My STOP LIGHT fuse, #9 in the instrument panel fuses, had blown! Per my diagnosis checklist above, in #2, if there is any problem in the stop light circuit the car will not go to READY mode. A blown fuse is a problem in the stop light circuit. I replaced fuse #9 and I now get READY mode with no problem.

    Yes I want to see the correct codes once car completes a good drive cycle again. Thanks for all of your help! Lee
     
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  15. dolj

    dolj Senior Member

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    Oh, I see what you mean about the idiot lights, so just a red herring to throw us off. LOL

    Glad you got it sorted.

    Nothing like good old step by step methodical troubleshooting.

    All the best.
     
  16. Dxta

    Dxta Senior Member

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    Hi. I just wanted to be clear here.
    I have similar issues.
    I replaced my 12V battery, no success.
    Swapped another battery, no success.
    I'd check my brake switch tomorrow then
     
  17. leemcgee

    leemcgee Junior Member

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    Good morning, my Prius was TOTALLED last fall, another car hit it from behind right rear quarter, the 12V battery area completely damaged, Optima Yellow Top will not fit there any more, the Yellow Top was damaged and no longer works. I have the totalled car here at home.

    I bought from Ebay a 31 dollar Power Monster 12V deep cycle AGM battery, smaller than the yellow top and only 20 amp hour, but this battery starts the Prius to ready mode just fine. With 20 amp hour vs. the yellow top 38 amp hour I will not be able to play my CDs with car turned off for as long.... But the new 31 dollar eBay battery works fine.

    The positive cable is much smaller, needed rewiring, the negative cable still fits.

    31 dollars is a lot cheaper than 166 dollars for the Yellow Top.

    My experience has been - 9.5 volts on the battery gets you READY mode just fine. 9.4 volts will not do it.

    All of this just an FYI for you all. I guess I will not get 500,000 miles on that Prius!
     
  18. bisco

    bisco cookie crumbler

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    is it age and vented, in case you get hit in the arse again?