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HV relays not being energized after battery replacement

Discussion in 'Gen 2 Prius Technical Discussion' started by CWShop, Mar 26, 2012.

  1. CWShop

    CWShop New Member

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    Codes indicate bad battery block 10. One of the cells in block 10 had lower voltage than any other cell in the battery. Ordered new cell and replaced it. The 12V battery was never disconnected, but the battery ECU was disconnected to allow it to be moved out of the way for bolt access. After reassembling the battery with the replaced cell, the no-load voltage of the battery is 215V. The car powers up with the alarm indicators still on (as expected) but putting the car in drive and pressing the accelerator has no effect. I double checked my connections. The HV relays are not being energized. Do the codes need to be reset before the car will move?
     
    #1 CWShop, Mar 26, 2012
    Longinus876 likes this.
  2. edthefox5

    edthefox5 Senior Member

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    Check 12 volt battery under load.

    And you probably not have the hi volt connector all the way engaged & fastened. It has to be pulled all the way down then locked. Easy to think its all the way on.
     
    #2 edthefox5, Mar 26, 2012
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  3. uart

    uart Senior Member

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    There's an auxiliary contact on the orange HV isolation plug that doesn't engage unless the handle is engaged in a certain way. There's quite a few descriptions of it here if you do a thread search. I think it causes exactly the issues you mention.
     
    #3 uart, Mar 27, 2012
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  4. CWShop

    CWShop New Member

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    Thank you, that was it! The isolation plug was fully inserted and the handle swung up but not slid down to lock it. On the first start, there was no change in the symptoms, but the second start reset all but the master alarm and the ICE did start. We shall see if the master alarm goes away after a few starts, or if it must be reset by the dealer.

    Update: The master alarm did reset after the fourth start. Repair complete. Total cost $35. Dealer quoted $3800. :)
     
    #4 CWShop, Mar 27, 2012
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    An alternative is just to disconnect the 12V battery negative terminal cable where it connects to the body, for several minutes, then reconnect. That will clear any DTC other than those logged by the SRS and skid control ECUs.
     
    #5 Patrick Wong, Mar 27, 2012
  6. vovila

    vovila New Member

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    Hi guys,
    I got some problem with my 2008 Prius, I would appreciate your help. My problem looks similar to the one here, but the info did not help. I changed 12 V battery of my 2008 Prius, but I can not start it. This was the second time I changed the battery, so can't say I did something wrong. The difference was that, this time I started changing the battery in the evening, since it was dark in my garage decided to finish in the morning. So battery stayed disconnected until the morning, does this make difference? Thank you for any help. I checked all the fuses, all fine. Also, I noticed that fuses on the driver side show zero volts, on the engine side 12 V as should.
     
    #6 vovila, Dec 17, 2020
    Last edited: Dec 17, 2020
  7. R-P

    R-P Active Member

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    Could you elaborate? This doesn't make sense to me. EDIT: you mean in the cabin the fuses don't get any power but in the engine bay they do?

    I recently left the 12V battery unhooked for a day and it lost all mpg and day-odometer settings. And possibly the fuelgauge had to recalibrate itself. So it does do something, ut I doubt it would criple the car in the way you describe.
     
    #7 R-P, Dec 28, 2020
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    If you have 12.6V at the battery and at the engine - underhood fuse block (the jump start point), did you try to hold down the brake pedal and press the power (ready) button several times?

    I also wonder if you have a bad capacitor in the Combination Module (aka "speedo")? It is a very common failure on Gen2, will cause this very same symptom, and can be "triggered" by high(er) voltage of a brand new 12V battery. Check the sticky thread "diy combination meter repair" in the gen2
    Care maintenance and troubleshooting forum.

    Posted via the PriusChat mobile app.
     
    #8 mr_guy_mann, Dec 28, 2020
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