Replaced Hybrid Battery - Won't Start

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by marksongs, Jun 4, 2022.

  1. marksongs

    marksongs New Member

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    I'm new to this forum, but for the short time that I have had my 2005 Prius, I have to say that I really love it - even in spite of the current problem!

    Background:

    About a month ago, I got the red triangle of death. I took my Prius to the local Toyota shop told them my budget was really tight and asked if they could just check the OBD codes for me so I that I could confirm what I suspected, that the Hybrid battery was going bad. They helped me (thank you, Toyota!) and this was confirmed. Having a tight budget, I scoured the internet for possible solutions, and decided to try to rebuild the battery to keep the car running until I could afford to replace the batter with a "new" battery (probably a rebuilt aftermarket battery with a 3yr warranty). So, I went to a nearby salvage yard that specializes in foreign cars and picked up a Gen 2 Hybrid battery core, hoping that there might be some salvageable modules in it to swap into my current battery. I then purchased a hobby charger from a local hobby store, that charges 2 NMIH batteries at a time and set out to test the modules on the core. I ended up having to order another hobby charger that can discharge and cycle NMIH batteries because the first charger did not have that capability, and because in order to ascertain the true capacity of each module, I needed to run a discharge cycle.

    So, because it takes about 3 hours on average to cycle (charge/discharge) a module to check its capacity, I spent the past couple of weeks charging and discharging modules as time permitted. During this entire time, I was still able to drive my Prius with the "red triangle of death" on, but I had to stop frequently to charge up the battery on my way home in order to have enough power to make the ascent into the mountains where I live. By last weekend, I was ready to pull the Hybrid battery from my vehicle to see what I had and to rebuild it. I only found 2 modules that had decent capacity left - most of the other modules were around 50% or less - so I ended up using the 26 modules from the salvaged core and added the two good ones from my battery and put them into the battery block, hooked them together in parallel to make one big 7.2 volt battery, and charged them all of them at 5 amps for an hour, at 2.5 amps for the next hour, and so on until I reached .3 amps. Then I let the battery sit for about 12 hours so that the voltages between the modules would equalize. I was in a bit of a rush to get back on the road, or else I would have let the battery sit longer to make sure that the voltages were all balanced as closely as possible. I then rebuilt the modules into the original configuration, pairing the highest capacity modules with the lowest capacity modules into the 14 blocks in order to normalize the capacity and voltages for each block, since the ECU reads by blocks and not by individual modules. I then fastened the battery block back into the battery housing, and reattached all of the temperature sensors, bus bars, and vent hosing, and fastened to cover in place.

    I reinstalled the Hybrid Battery, and inserted the orange safety plug, pulled lever up, and slid it down into place.

    First Problem:

    At this point, I attempted to start my Prius and the console would not even come on. I searched online for a solution, and decided to check the 12 volt system, and indeed, the 12 volt battery only had 5.74 volts! At this point, I know what happened: thinking that the Hybrid battery was needed to power the trunk latch, I left the trunk propped open with a floor mat without thinking to detach the negative terminal to the 12 volt battery, and so even though there were no visible lights on in the trunk area, there must have been a circuit that was closed due to having the trunk open, causing the 12 volt battery to discharge over the weekend. So, I took the 12 volt battery inside and charged it over night, and by the morning it was reading 13 volts (which is pretty amazing - but I recently checked it and it is currently reading 12.2 volts).

    Second/Current Problem:

    I put the 12 volt battery back in my Prius and tried to start it. This time the console lit up, but it would not shift into Drive or Reverse, or start the gas engine (from what I have read, I believe that this means it will not go into ready mode). Today, I went to a nearby auto shop and borrowed an OBD reader. The reader was just a generic reader, and so it did not give me a lot of information. It generated the following codes -> C1241, C1259, C1310, and U0293. I called some shops that work on Hybrids and got some feedback about the codes and the situation - but nothing conclusive. There was one person who seemed to be very sharp, and who knew what the codes were without even having to look them up. He explained that the C1241 related to my 12 volt system, and indicated that my 12 volt battery was low (does 12.2 volts count as low?), that C1259 relates to my regenerative braking, that U0293 indicated that one or more modules were not communicating with each other, but that the core issue was with C1310, which indicated some kind of problem with the HV System.

    So, what could the problem be? I called a few more people who were nice enough to try to help me, and I tried to get some more clarity - specifically, I was concerned about whether I had balanced the battery properly/sufficiently so that the ECU would not pick up too great a difference in voltage between the 14 blocks in the battery. People gave me different answers: one person told me that new batteries shipped not more than a .05 volt variance between modules; another person told me that the variance between blocks could be up to 1.2 volts. But he also seemed to think that the car would still start. He advised me to reset the error codes by removing the negative terminal to the 12 volt battery (just in case). I tried this, and no codes were cleared (this didn't make sense to me anyway, because the 12 volt battery had been out of the car over night when I was charging it).

    This is all the information that I have gathered to-date on the problem. Any help with troubleshooting would be greatly appreciated!
     
  2. dolj

    dolj Senior Member

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    Any time you have disconnected the 12 V battery, the first time you attempt to start the car (foot on the brake press Power button once) after reconnecting the 12 V battery, it will light up the dash as if you pressed the Power button twice with your foot off the brake. You need to press the Power button a second time (with your foot still on the brake) to get the car to go READY.
    C1241 means that at the point the code was set voltage was sensed low inside the skid control ECU. It does not necessarily mean the battery is too low as indicated by that 'one person.' 12.2 V while is low, it should not have a material effect on what is going on. It wouldn't hurt to monitor the voltage when you start the car, and as long as it remains above 10.5 V it is not going to cause a problem in and of itself. However, if the voltage is dropping low, (less than 11.5 V) you might be needing a new battery. They don't do well when deeply discharged.
    C1259 can mean that the orange service plug grip is not actually connected. Although you said you 'pulled the lever up, and slid it down into place', did it actually click when you pressed it firmly down?
    C1310 is a feedback code set by the VSC/TRAC system to acknowledge that it heard there was a problem in the hybrid vehicle control system.
    U0293 means communication between hybrid vehicle control and battery ECU has been lost.

    So I'd go check that the orange service plug is indeed firmly connected. That would explain all but the U0293.


    BTW, Your posts are moderated until you've posted 5 or more times. We cannot see your posts until they are released by a mod, Go find another few posts and post a comment on each to get up passed 5 posts.
     
    #2 dolj, Jun 4, 2022
    Last edited: Jun 4, 2022
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    C1259 can mean that the orange service plug grip is not actually connected. Although you said you 'pulled the lever up, and slid it down into place', did it actually click when you pressed it firmly down?

    Another thing that is semi-common on DIY rebuilds is that the battery wire harness that plugs into the bottom of the safety disconnect socket gets forgotten about. It often gets unplugged when disassembling the battery, but being out of sight, gets forgotten about during reassembly. If this plug isn't installed, the car still thinks the safety disconnect is removed.
     
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  4. marksongs

    marksongs New Member

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    Thanks for the quick response! After looking at your post, I was alerted to the significance of code U0293. I was originally focused on the work that I had done on the Hybrid Battery in terms of balancing its voltages, but was unclear as to whether or not unbalanced voltages would cause the car not to start. However, I just looked at an article on this code. The article indicates the code U0293 would prevent operation of the vehicle. I will definitely go check the orange plug again to see if it "clicks." I have read that this is a common issue, and although I have gone through the process at least 3 times, it won't hurt to try it one more time.

    But, if the orange plug clicks into place and the car still refuses to start, then I think that I am going to need a diagnostic tree to follow in order to check for possible grounding problems, shorts, and/or blown fuses.

    Thank you again for your response. Any help is appreciated!
     
  5. marksongs

    marksongs New Member

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    I just checked the orange plug for the 4rth time, and it definitely clicks into place.

    When I was removing the Hybrid Battery, one of the bolts that fastened a part over the two orange cable was stuck, and the sheet metal was apparently pretty thin and started to unexpectedly twist. When I reinstalled the Hybrid Battery, I used some needle nose pliers to try to straighten the twist out as much as possible, but after I fastened the cover that connects the driver's side chassis to the hybrid battery, it looked like the connecter cables were awfully close to touching the sheet metal cover. I am hoping that this did not cause a ground-out.

    Also, there was this thin bit of tin that draped over the two cables, but because I did not recall exactly how it was supposed to drape/attach to the cables, I did not attempt to install it. It might be some kind of shielding - I'm not certain what its function is.
     
  6. marksongs

    marksongs New Member

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    Here are pictures of the twisted section.
     

    Attached Files:

  7. dolj

    dolj Senior Member

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    It is installed with the two 'divots' facing down and touching the cable shielding, kind of the opposite of what you'd think.

    You need to straighten that tab a bit more so it is in line with the other one and you definitely need to install that strap. It provides a necessary earthing connection. I use a long flathead screwdriver poked in down to the floor and wedge the tip against a convenient anchor point then apply opposing force at the handle end to stop the tab twisting. It is not the best design in my opinion. Makes me wonder if there is a Toyota 'special service tool' they use to brace it.

    upload_2022-6-6_0-26-14.png
     
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    Did you fully understand TMR-JWAP's post? Did you confirm that the small 2-wire connector that goes into the bottom of the orange service plug socket is connected? Sliding the plug handle down SHOULD connect two little pins in the socket that connect to the battery ecu (and then up to the inverter cover and all the way back to the hybrid control ecu). If anything is wrong with that circuit anywhere, then you get an interlock code.

    Are all of the connectors for the battery ecu fully seated? Did you check all of those connectors and the receiving sockets on the ecu for corrosion or damage to the terminal pins?

    If the battery ecu can't talk to the car then the hybrid system won't work. I might suggest that you should have your own scantool in order to be able to check codes and data as needed.

    There's a review for apps at the top of the Gen2 Technical discussion board (the "sticky"section ). I like the Autel Maxi AP200, it gives you codes and data for all ecu's on a Gen2.

    Lastly, if the HV battery block voltages are different (enough) from each other, then it can throw certain fault codes and completely prevent operation. More often the car will operate but one "just" gets poor performance and P0A80 (replace battery) code.

    Posted via the PriusChat mobile app.
     
    #8 mr_guy_mann, Jun 5, 2022
    Last edited: Jun 5, 2022
  9. marksongs

    marksongs New Member

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  10. marksongs

    marksongs New Member

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    Thanks. I will see what kind of straightening I can do, and see if I can locate that aluminum piece of shielding and put it back in place. Are there any particular fuses/relays that I should check while I am at it?
     
  11. TMR-JWAP

    TMR-JWAP Senior Member

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    Yes, you really should fix that a bit better, and install the strap. You are likely losing continuity between the car chassis and the cable shield at that location.

    Look at the photo where you showed the three car harness plugs that connect to the three sockets on the HV battery.
    The plug on the right inserts into the ECU
    The plug in the middle supplies the operation of the relays and other 12v stuff.
    The plug on the left is two wires that go down behind the safety plug socket. Those wires go down behind the socket and into another white plug that inserts into the disconnect. That plug is what carries the signal that the disconnect is fully inserted. If that is not inserted, the car will never know if the safety plug is installed.

    So again, look at the left plug and follow the cable that goes behind the orange plug, it's only a few inches long. Make sure its other end is inserted correctly.

    This is what it looks like: The socket is connected to nothing. It has a small hole in the top. When you insert the safety disconnect, there's a tab that aligns with that hole. When you perform the final (3rd) step, a shorting wire is pushed down into that hole and connects the two wires from the plug. That short provides the signal to the car that the safety disconnect is inserted correctly.

    interlock socket.JPG
     
    #11 TMR-JWAP, Jun 5, 2022
    Last edited: Jun 5, 2022
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  12. marksongs

    marksongs New Member

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    So, what this picture is showing is the place where the safety plug goes - right? If the wires are all connected properly, could the female plug fixture have an issue?

    BTW, I inspected the connectors in my last picture above, and they all seemed to be clean and intact. I also checked fuses that looked relevant, but they all looked fine.

    I'll go take a look at this - maybe the connector came loose or something when installing/uninstalling...

    Thanks.
     
  13. marksongs

    marksongs New Member

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    From what I can tell, it is inserted correctly. At this point, it looks like I am going to have to remove the battery again, at which point, I can inspect it more thoroughly. But, unless it was somehow jostled loose, that plug should have stayed exactly where it was because I never detached it.
     
  14. ChapmanF

    ChapmanF Senior Member

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    C1259 and C1310 are both such "feedback" codes. They are set in the skid ECU whenever the hybrid vehicle control ECU has reported any trouble codes (of any kind). So when you see C1259 or C1310, you generally see them together, and they just mean you should make sure to get the codes from the HV control ECU and pay attention to those.

    If the safety interlock circuit is open (usually at the orange plug on the battery, but it protects certain covers on the inverter too), that'll be a P0A0D code in the HV ECU. So you'll get the C1259 and C1310 because there's a code in the HV ECU, but it's that HV ECU code that tells you what the issue is. If it's not P0A0D but something else, then it's telling you about some other problem.
     
  15. marksongs

    marksongs New Member

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    The code reader that I borrowed from the local shop only showed the 4 codes that I provided (above). Are you saying that: 1. I should be getting some additional P-codes with those 4 codes, and 2. that another code reader, such as one that could be purchased from Amazon and connected to my smartphone via bluetooth would provided me those P-codes?
     
  16. marksongs

    marksongs New Member

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    Update:

    I removed the battery block from the vehicle and tested the voltages on each module to see if there were any issues. My max voltage was 7.85, and my minimum voltage was 7.34. Most of the voltages come in around 7.80 and jump either up or down by .01 volts. About 10 of the modules have voltages that jump across a .03 to .05 volt range. When I pulled my original batter block, each module (except for maybe one or two) tested at 7.95 volts within .01 volts and did not jump up or down in voltage at all - but load tests on those modules showed that most of them were at about 30-50% capacity. The rebuild battery block contains 26 modules from the salvaged core. I suspect that a longer balancing time will help to stabilize the voltages within each module, as well as normalize them across the battery block.

    Someone was helping me look through these forums earlier, and that said that they found a couple of posts that indicated that a 12 volt battery with less than a 12.6 volt charge on it might also cause issues. The last time I checked my 12 volt battery, it was at 12.2 volts. Would this be a legitimate cause for preventing the car from engaging drive/reverse/starting-the-gas-motor?

    Thanks.
     
  17. ChapmanF

    ChapmanF Senior Member

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    Exactly. This kind of thing frequently happens; some generic code reader will have no trouble seeing the C1259 and C1310, because those are in the brake ECU, and cars very commonly have brakes, so code readers look there. But the generic reader won't show you the codes in the HV control ECU, because not all cars have one of those, and the generic code reader doesn't know to look there.

    On the bright side, this gives you a good way to know when you're using a code reader that isn't giving you the goods. If you see C1259 and C1310 and you don't see any HV control ECU codes (which the C1259 and C1310 tell you must be there), then you know you need a better code reader.

    mr_guy_mann has recently reviewed a bunch of the options:

    Gen2 OBD2 app review | PriusChat

    As for the aux battery voltage, if you look in the repair manual, you'll typically see notes advising you to charge or change the battery, before proceeding with diagnosis, below a certain voltage, 10.5 in many spots in the Gen 2 repair manual, usually 11.5 in a Gen 3 repair manual. If you like, just take the more-conservative 11.5 figure. And yes, those are conservative figures; the only voltage-related difficulties I've ever had in a Prius were well below those.

    The idea that the something after the decimal point in 12 point something is going to explain some misbehavior of the car is one of those PriusChat things that just won't go away.
     
    #17 ChapmanF, Jun 6, 2022
    Last edited: Jun 6, 2022
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  18. marksongs

    marksongs New Member

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    Thank you. This makes a lot of sense.
     
  19. marksongs

    marksongs New Member

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    I'm reassembling the battery pack, and I am trying to pay close attention to details as I go. With the pack out, I was able to see that the plug that you mentioned was inserted correctly. I also inspected the temperature sensor wiring, and visually, everything looks good. As I am attaching the base of the housing to the bottom of the battery block, I am noting that there are 6 modules that will not take bolts - either because there are bolt pieces stuck in the threaded holes, or the bolt hole size is different, or the bolt hole is cross-threaded. Could this cause a grounding problem, or are these bolt holes strictly for fastening the battery block to the battery unit casing?
     
  20. marksongs

    marksongs New Member

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