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Replacing 89892-47020 Sensor Battery Voltage ECU P0B42 B Circuit Low

Discussion in 'Gen 3 Prius Main Forum' started by kilimar, Dec 6, 2022.

  1. kilimar

    kilimar Junior Member

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    I have 2010 Prius (Gen 3). I'm curious if anyone has replaced their Battery Voltage Sensor ECU part # 89892-47020 with part # 89892-47080. I believe the units are interchangeable but that's "WWW" knowledge -- I'm looking to see if anyone has actually done it.

    I believe the 89892-47080 units can be found Prius 11-15.

    The Long of it:

    So, I got check engine with
    P0B42 Raw code: 0B42 ECU: 7EA Status: Confirmed OBDII: Hybrid battery voltage sensor B - circuit low
    Opened up the hybrid battery pack and saw minor corrosion along on the bus bars (both). I cleaned it with a brass brush and then light solution of vinegar/water and dried everything. For the ones with the sensor wire, I took all the nuts off and soaked in the acidic solution. It was very difficult removing the sensor wiring harness from the Sensor module due to corrosion on pins 1, 11, & 12. I cleaned as best as I could using the brass brush and acidic solution. For the wiring harness, I checked for continuity from the eyelet to the connector -- all were good. Before reinstalling, I used DetoxIt D5 on the wiring harness head and the ECU socket. Result was no joy. Current conclusion is that the Battery Voltage Sensor ECU is bad. eBay.
     
  2. Elektroingenieur

    Elektroingenieur Senior Member

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    The interchange is also listed in Toyota’s Electronic Parts Catalog data: for all models and years where 89892-47020 was used, it was superseded as a service part by 89892-47080, effective September 27, 2012.
     
  3. kilimar

    kilimar Junior Member

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    Doh! Thank you. Don't know why that didn't come to mind... looking on the Toyota parts website.
     
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  4. kilimar

    kilimar Junior Member

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    The used eBay replacement battery ECY module fixed the issue (no more Check Engine light). However, I do have a question about the code. If you look at the attached image, it states "Archive (inactive)" and "Status: Permanent". Even after clearing the code and the Check Engine light is out, the below 'code' shows up when scanning for codes. Is this correct?

    P0B42.png
     
  5. ChapmanF

    ChapmanF Senior Member

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    Typically for a permanent code, it will be there until the system has successfully passed its monitor test after the problem's been fixed. The confirmation driving pattern in the manual for P0B42 doesn't seem to involve much beyond doing a code clear and a universal trip.
     
  6. kilimar

    kilimar Junior Member

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    Ah, thank you. I do, now, recall reading the above some where with other codes as well. I'll have to check again as we did drive to the grocery store this morning (very short drive; but we are also driving to Tampa tomorrow (2 hr drive).
     
  7. KozNouri

    KozNouri New Member

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    Did you have to do any programming after replacing 89892-47020?
     
  8. kilimar

    kilimar Junior Member

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    No programming was done. Just replace the unit and put everything back together... Of course, with that said, about a month ago, I got a P0B51 code.... (Hybrid battery voltage sensor E - circuit low)... going to have to open it back up again and check all the connectors as well as check the torque on the nuts. I don't think I use an toque wrench when I put it back together....

    48"-lb. or 5.4N*m. (https://attachments.priuschat.com/attachment-files/2020/01/181225_Torque_Value.jpg)
     
  9. kilimar

    kilimar Junior Member

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    So this is the replacement board that I put in 1 year ago. More KOH leakage from the battery made it through the wiring and into the connector. You can see a chunk of the blue crystal on the the top pin by the orange connector. I'm guessing enough liquid made it the connector that it started sparking between the sensor connectors? There was enough heat and/or corrosion that for one pin there is a gap between the pin and the board.

    57e5a3d8751f0627c4e203df5272e1c80aa589bc-1.jpg 7931ccbdb529e348a1171ee03e1d85949f814ff0-1.jpg

    I'm going to pick up another board ... additionally, this time, I soaked the whole "bus bar" (Prius 2010 Toyota 82165-08140 Wire, Frame, NO.2 or Toyota 82165-26560 Wire, Frame, NO.2) in diluted white vinegar over three days -- hopefully to neutralize any KOH inside the wiring as well as cleaning/neutralizing the oxidized copper/acid on the metal contacts.

    So.... replacing the board when there is KOH leaking through the wiring is a short term fix (1 year in my case). Replacing the wiring harness is probably also a short term, but possibility a longer term.