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Tricky voltage issue

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by R.J.C., Mar 11, 2018.

  1. R.J.C.

    R.J.C. New Member

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    Greetings,

    I've been lurking around the forums for a couple of months now and finally found something I couldn't figure out by searching.

    I recently bought a 2004 Prius with a bad HV battery. I bought an RC charger and went to work on it. I was able to salvage all but 3 of the modules, changed them out, did a final balance connecting all grounds and all positives, things were looking great. Reinstalled the battery and I'm getting a P3030 code and blocks 10 and 11 are bouncing from positive to negative voltage. It reads decent positive voltage in relation to the rest of the battery, but about every five seconds or so it'll jump to negative 14 or 15 volts for a second then go back to a normal positive voltage. Anyone have any ideas? Thanks in advance!
     

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    #1 R.J.C., Mar 11, 2018
  2. Dxta

    Dxta Senior Member

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    Your problem might be coming from corrosion ridden voltage sense wires on the particular blocks, or the maybe the battery ECU pinouts has got some rust and all that in it. Try removing the ECU and take a look at it. Did you clean the bus bars of coreoa, and applied dielectric grease on the module studs?

    If after the above, you're still getting the same problem, modules on the blocks you referenced are faulty.
     
    #2 Dxta, Mar 11, 2018
    R.J.C. likes this.
  3. R.J.C.

    R.J.C. New Member

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    If the weather isn't too crazy I'm gonna pull the battery back out tomorrow. I was hoping to avoid it as I've already replaced all of the interior, such is life.

    I did clean the block bars and the nuts fairly well. There was still a little buildup, but not as much. I did soak the nuts too long and they lost their coating, I didn't think it'd be an issue. I didn't think to use any dielectric grease. Also sprayed some clear coat I had lying around on the contacts before I put the lid back on in hopes it'd prevent further corrosion.
     
    #3 R.J.C., Mar 13, 2018
  4. edthefox5

    edthefox5 Senior Member

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    Where did you spray clear coat? There really should be nowhere that clear coat should be used.
     
    #4 edthefox5, Mar 13, 2018
  5. R.J.C.

    R.J.C. New Member

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    I applied the clear to the bus bars and nuts after I'd reinstalled them and everything was tightened up. I'd seen it done in a video or thread I was looking at.
     
    #5 R.J.C., Mar 13, 2018
  6. padroo

    padroo Senior Member

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    I wonder if the clear coat could be conductive?
     
    #6 padroo, Mar 14, 2018
  7. exstudent

    exstudent Senior Member

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    The original bus bar and nuts, do not have a clear coat.

    Take all videos with a heavy grain of salt, unless it comes from the manufacture. You wouldn't jump off the Golden Gate Bridge because 26 known jumpers actually survived, despite some living with life altering injuries?

    Module replacement is short term, and not a long term reliable repair.
     
    #7 exstudent, Mar 14, 2018
    edthefox5 and padroo like this.
  8. R.J.C.

    R.J.C. New Member

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    Well that's not good...
    Safe to just clean this junk out?
     

    Attached Files:

    #8 R.J.C., Mar 23, 2018
  9. edthefox5

    edthefox5 Senior Member

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    No cleaning it out is not going to work very well because the female socket side is going to be rotten too and thats impossible to clean.
    Its not just surface crap the pins and socket are corroded.

    It will be extremely intermittent at the very least if just cleaned up and the ECU needs very solid connections. I would buy a new harness and cut the end off and unsolder and remove the male plug on the ecu circuit board and solder the new harness wires right to the ecu board. Pin for pin.

    Take the ecu metal case off the circuit board and take the circuit board off it may have alot of corrosion on the board itself. You got a rotten box there I'm afraid..
     
    #9 edthefox5, Mar 23, 2018
  10. Prodigyplace

    Prodigyplace Senior Member

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    The "junk" in the female connector is the remains of the corroded pins from the other connector.
    The connectors need to be replaced. Perhaps some other parts too. Something caused that connector to sacrifice itself.
     
    #10 Prodigyplace, Mar 23, 2018
  11. R.J.C.

    R.J.C. New Member

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    Popped open the ECU, looks great aside from a little corrosion on the backside of the orange connector. Does anyone know where I could find a replacement connector to put in so I don't have to buy a new ECU?
     
    #11 R.J.C., Mar 23, 2018
  12. Prodigyplace

    Prodigyplace Senior Member

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    #12 Prodigyplace, Mar 23, 2018
  13. R.J.C.

    R.J.C. New Member

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    After spending a couple of hours looking for the connectors to no avail it appears I have to buy a new ECU, crud.
     
    #13 R.J.C., Apr 3, 2018
  14. Prodigyplace

    Prodigyplace Senior Member

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    You also need the connector from the harness that attaches to the ECU.
     
    #14 Prodigyplace, Apr 3, 2018
  15. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Look on eBay for a used unit, they are not very expensive.
     
    #15 Patrick Wong, Apr 3, 2018
  16. ChapmanF

    ChapmanF Senior Member

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    I would just go buy that harness. It would be very tedious to try to disassemble an old rotting one and reconnectorize it with the pins in the right order, and safely. Because that one is made with skinny wires, it can be easy to forget it's a high-voltage harness, but it is, and the place where all those wires neck together ahead of that connector is the one place in the battery where you have the very highest voltage gradients (voltage difference divided by the physical distance between them). I do not know what insulation they use on those wires, but definitely not every formula can be that skinny and still up to the job. I would go ahead and let the factory build that harness.

    Another place you can find a lot of pictures of connectors in that condition is on the "Battery fires at ECU sense connector" thread. Just sayin'.

    -Chap
     
    #16 ChapmanF, Apr 3, 2018
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