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P0A0D to no end…

Discussion in 'Gen 3 Prius Technical Discussion' started by Awells80, Jul 15, 2024.

  1. Awells80

    Awells80 Junior Member

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    IMG_4173.png IMG_4173.png IMG_4179.png IMG_4069.jpeg IMG_4076.jpeg IMG_3994.jpeg IMG_3985.jpeg Hello to all. I had a hybrid battery that I had to replace a few modules in, so I took it out of the vehicle and did several different load tests on each individual module in different conditions and the failed modules have now been replaced and grid charged to 137v total pack voltage, then discharged, then charged back up, left for 24 hours, checked voltages, then load tested, etc. Everything was fine so I topped off the charge and put the battery pack back in. With the downtime on waiting for charging and discharging, I also cleaned the whole EGR system, which doesn’t amount to much on my concern I don’t think.

    I put the battery is back in and all plugs are plugged in, including the interlocking switch (yes it’s in correctly, 100%). I have tested this circuit and it’s good but the battery voltage sensor ecu is saying otherwise.

    This has been a nightmare and I’m reaching out in hopes of someone out there who has experienced this because I’m out of what the heck to do next.

    Will not go into “READY” mode. Hybrid battery COOLING FAN is on as soon as the ignition is “on” and remains on until I power off the ignition.

    I have replaced all the bus bars and nuts. I have replaced the bus bar wiring harness to the battery ecu and I have also replaced the whole junction relay box with new relays.

    Techstream says as follows:

    P0A0D
    P0AE7
    U029A
    P0453

    Also,
    Anyone know what “connector cover assembly” is in the “ILK” circuit right before it gets to the “air conditioning harness”?

    Thanks in advance. I’ve learned so much from this forum!
     
  2. ChapmanF

    ChapmanF Senior Member

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    The ECU that's responsible for monitoring the interlock circuit is the power management control ECU.

    Not positive, but in the diagram you are referring to, all three of ("inverter terminal cover", "no. 4 floor wire", and "connector cover assembly") are shown as being within the inverter with converter assembly. My first guess would be that you find more than one independently openable terminal cover on the inverter, and a pair of interlock contacts beneath each one.

    None of those would normally be the cause of a P0A0D unless you had removed any of those covers on the inverter.

    Only the P0A0D code is about the interlock circuit. The other codes you have indicate other issues and should be looked up on their own.
     
  3. Awells80

    Awells80 Junior Member

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    Not positive, but in the diagram you are referring to, all three of ("inverter terminal cover", "no. 4 floor wire", and "connector cover assembly") are shown as being within the inverter with converter assembly. My first guess would be that you find more than one independently openable terminal cover on the inverter, and a pair of interlock contacts beneath each one.

    None of those would normally be the cause of a P0A0D unless you had removed any of those covers on the inverter.

    Only the P0A0D code is about the interlock circuit. The other codes you have indicate other issues and should be looked up on their own.[/QUOTE]

    ahhh.. Yes. The inverter cover I’m not sure why I didn’t realize that yesterday. That should be fine under the cover. This P0A0D that has been brought upon me is beyond me and I’m not understanding what could possibly be the problem but when I can accomplish that, I can at least get into ready mode and other codes my disappear along with it would be nice.

    My fan kicks on and it remains on which could indicate a stuck relay by chance and will check it as soon as I get a moment..?..
    As for this interlocking switch trouble code, I think I might just trace the 2 wires back and see where they go exactly. I jumpered them together at the interlocking switch at the connector, so that’s isolated from being the problem. The leads coming off the battery have the packs volts being delivered to the junction box with the switch engaged as well.
     
  4. Awells80

    Awells80 Junior Member

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    I’m not sure that I replied correctly, format wise...
     
  5. Awells80

    Awells80 Junior Member

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    **Update**

    Last week I bought a subscription to Alldata to diagnose my situation. All my symptoms and testing lead to a faulty Power Management ECU. I ordered the part and received it in the mail today. I will be replacing the old with the new and will post my results afterwards for anyone who has a similar situation at hand, but I do recommend anyone with a no “ready” mode problem, to use the repair manual for their own diagnosis that will likely be different than mine.
     
  6. Awells80

    Awells80 Junior Member

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    Well I replaced the Power Management control unit, as Alldata suggested and not a damn thing changed but another code added to my list. B2799 Awesome.
     
  7. ChapmanF

    ChapmanF Senior Member

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    Now that you've subscribed to service information, you ought to have access to the wiring diagram, which will let you plan out your troubleshooting without having to physically trace wires back (which can be hard, with so much of the wiring harness wrapped up in tape or tubing). The diagram is really your friend for this stuff.

    The interlock circuit is a very, very simple series DC circuit that could be used as an early textbook example for diagnosis with a simple meter.

    That was a good step that shows you thinking on the right lines, and if you can just stay focused on locating the open in that simple circuit, I'm pretty confident you will get somewhere.
     
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  8. Awells80

    Awells80 Junior Member

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    A little update for those interested. After replacing the power control management, I decided to test the individual modules. During my testing, I found that one of the two modules I bought off eBay was reading around 7V. All the others tested between 7.6 to 7.7 V. This is after the battery pack sat for about a month. I have yet to accomplish getting it back into ready mode.

    I put a good module in its place, charged the pack all the way up and reinstalled the pack. Nothing changed. The only difference I saw was Techstream didn’t pull my vehicle up automatically with the Vin number as it used to. I manually put in the Vin number. Now the hybrid battery has a full charge as well as 12 V because I keep it on a maintainer! What I am doing wrong I am eager to find out one day! LMAO.
     
  9. ChapmanF

    ChapmanF Senior Member

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    Do you still have a P0A0D code? If so, track down where the open circuit is and fix that.
     
  10. Awells80

    Awells80 Junior Member

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    I do indeed still have the P0A0D code. My Techstream does not display any of the battery cell values correctly, Same goes with the hybrid battery’s overall voltage.( Reads exact same numbers no matter what ). Is this because of the U029a code?
     
  11. ChapmanF

    ChapmanF Senior Member

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    Why are you doing so much other stuff before tracking down the open interlock circuit indicated by P0A0D?
     
  12. Awells80

    Awells80 Junior Member

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    Well, actually today I did some testing on the interlock wiring from the interlock to the connectors and I made some progress. Big time. You’ll never believe this, but come to find out, there are two identical plugs, right there around where all the plug-ins are for the GEN three that you disconnect in order to remove, the hybrid battery pack. Why they decided to do this is beyond me. W Idiot hile looking at the Alldata wiring diagrams for the interlock circuit, I noticed the wiring was going through one of the two connectors that are IDENTICAL. The key giveaway here was That one was going through the Tire, well to the side of the vehicle. (Canister). I thought to myself, there’s no way on earth that’s the right plug. I started searching around and not far from that plug was another. That was the exact same plug so I swapped them. Made more sense that I looked at it because the wiring kind of matched much better than the connector through the tire well!!

    I was finally getting continuity between The inverter and the interlock plug. From here, I went through every single connector with some carburetor cleaner and spray them with air cleaning them all. Few other things but long story short these are the before and after codes. I’m making my way.
     

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  13. Awells80

    Awells80 Junior Member

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    went through all the steps for the interlock code. Everything test perfectly except for this step here as I posted an image of below. It’s asking for 12 to 14 V and I’m only getting 5.8 or so.
     

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  14. ChapmanF

    ChapmanF Senior Member

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    So the voltage sourced by the power management control ECU on the other end of that wire is not making it to pin A62-35: even the high impedance of your voltmeter is able to pull it down to half what it should be.

    What does that say to you about the only places left where the problem can be?

    Your screenshot of the manual doesn't show what comes next, but that test should be followed by where to go if the test is NG, and where to go if the test is OK.

    Yours is NG, and I'm guessing the step it says to go to next will be called something like "check harness and connector (power management control ECU - inverter with converter)", and it might be a working hyperlink in the online manual you are viewing. If it doesn't work as a link, you should find the step with that name, maybe half a dozen pages or so further on in this same workup.
     
  15. Awells80

    Awells80 Junior Member

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    Thank you for the response. Your input is always inspiring and helpful. The next step following the ng is to replace the power control ecu, in which I have already done so previously and it didn’t change a single thing.

    The only thing I know to try would be to put the original power control ECU in and see what happens..?
     
  16. rjparker

    rjparker Tu Humilde Sirviente

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    What year and model hybrid do you have?

    I have to agree that you are going down the parts cannon road without solving your interlock problem. That road often leads to two or more concurrent problems when you started with one.
    Often assumptions like 100% good and total voltage good can turn out to be wrong but we can’t see it because we are sure it’s right.

    I would find a hybrid battery rebuilder and take your battery to them for inspection.
     
    #16 rjparker, Aug 1, 2024
    Last edited: Aug 1, 2024
  17. Awells80

    Awells80 Junior Member

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    #17 Awells80, Aug 1, 2024
    Last edited: Aug 1, 2024
  18. rjparker

    rjparker Tu Humilde Sirviente

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    Your scanner reported several problems but one battery problem often creates multiple other codes that go away once the root cause is resolved.
     
  19. ChapmanF

    ChapmanF Senior Member

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    I didn't see that because it was outside of your screenshot of the manual. Can you recheck that, and maybe screenshot the part of the manual that says where to go for ng and ok?

    I'm looking in a 2010 Prius manual instead of a 2015 CT200h manual, but that's definitely not the next step for ng in the manual I'm looking at. And I doubt the systems are different enough for that procedure to change.
     
  20. Awells80

    Awells80 Junior Member

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    The resistance between my A19-32 plug on the Power Control ECU to the A62-35 plug on the converter is below 1 ohm. With this step passing as good, the results are to replace the Power Control ECU, as I have done.
     

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    #20 Awells80, Aug 4, 2024
    Last edited: Aug 4, 2024