Replaced the 12v battery, now the car won't start

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Nirosorin, Oct 30, 2019.

  1. Nirosorin

    Nirosorin Junior Member

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    Guys, I need help!

    With the cold weather approaching, I decided it is time for a new 12v battery on my 2005 Prius. Being the original battery, it showed multiple signs it wasn't holding the charge anymore: the red triangle for a few seconds after ignition the morning, or after a few minutes with the hazard lights on, etc.

    I've purchased a new battery and Installed it today. Reconnected everything back and the car won't start. I have nothing, like I have no 12v battery Installed. No dome light, no power lock, nothing.

    I've connected the old battery with jump cables to the back, still nothing.

    But when I connected the old battery to the front jump-starting place, it started immediately and everything seemed ok.

    I thought the new battery is the problem so I put the old battery back to the car. The same result: has no power, but jump-starts ok when connecting the new battery with jump cables to the front.

    Both batteries (old and new) 12.37v. When the car is running, I have 13.6v in the front at the fuse box, and the same 12.37v in the back at the battery.
    When the car is off, the battery in the back stays at 12.37, but ground and + terminal at the fuse box mesure 0 volts. It looks like I've managed to blow a fise or something, it's like there's no link between 12v battery and fuse box.
    I've measured voltage at the connector exiting the + terminal of the battery, so after the Fusible Link Block on the + battery terminal, and the voltage is 12.37.

    I was extremely careful about polarity in all the steps I took: installing the battery, jump starting, everything. I've followed the steps exactly by the book. No shorts, no sparks, nothing happened.

    What did I do wrong?
    What should I check? Fuse, relay?

    Thanks!
     
  2. bisco

    bisco cookie crumbler

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    it is usually a bad connection at the negative cable to body ground spot

    and, you should charge up the new battery, the car won't do it for you, it just maintains it. a new battery should hold close to 13 volts
     
  3. Nirosorin

    Nirosorin Junior Member

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    You might be right. But now I have the old battery installed. Witch is not dead yet. And it's like I have no 12v battery at all.
     
  4. bisco

    bisco cookie crumbler

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    read the first sentence
     
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    Like Bisco said, plus....make sure the heavy cable is actually fully inserted into it's socket. Try removing it and inserting it again to make sure it clicks into place.

    The + terminal passes power through the terminal clamp, a bolted joint, into a busbar inside the fusible link assembly, through a 120 or 100 amp link and then to the plug where the heavy cable inserts. The small wire taps off the busbar through a 5 amp fuse.
     
  6. Nirosorin

    Nirosorin Junior Member

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    I have inserted everything multiple times (swapped the battery 2 times), I sanded the terminals and the ground connection spot. Sprayed electrical contact cleaner at every connection. I don't think is that.
     
  7. bisco

    bisco cookie crumbler

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    okay, thanks. i will keep thinking(n)
     
  8. bisco

    bisco cookie crumbler

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    afaik, the positive wire goes directly to the jump point. maybe a fuse at the battery?
     
  9. TMR-JWAP

    TMR-JWAP Senior Member

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    I have no idea of your electrical troubleshooting ability, but are you confident in your ability to trace the voltage from the + terminal all the way to the large cable crimp connector inside the fusible link assembly? Do it once with the negative meter lead connected to the battery (-) terminal. Then do it again with the (-) lead connected to the car body. Is anything different?

    Other options:

    Resistance checks:
    1. Put your (-) lead on the negative battery terminal and your (+) lead on the car body. Have someone wiggle the negative battery cable. Are there any fluctuations in the resistance reading? It should be ~0 ohms with no fluctuations.
    2. Put your negative lead on the (+) terminal of the battery. Jam the (+) lead into the crimp of the large cable and then wiggle the fusible link assembly. Check for the same.
    Other voltage check. Put negative lead on the car body at a clean metal point away from the battery. Put positive lead on battery + terminal. Is it showing 12v?
     
    #9 TMR-JWAP, Oct 30, 2019
    Last edited: Oct 30, 2019
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  10. Nirosorin

    Nirosorin Junior Member

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    I managed to insert my mesuring needle in the back of the white plug, there's a cupper bracket there, where the cable exits the plug, so after the battery fuses. And it mesured the same voltage as the battery.
     
  11. bisco

    bisco cookie crumbler

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    frustrating
     
  12. TMR-JWAP

    TMR-JWAP Senior Member

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    Especially to those of us that are electrical GURUS and know in our heart it would be a 2 minute job if there in person...……….
     
  13. bisco

    bisco cookie crumbler

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    that counts me out :oops:
     
  14. TMR-JWAP

    TMR-JWAP Senior Member

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    changed it slightly, lol.
     
  15. Nirosorin

    Nirosorin Junior Member

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    I'm pretty confident it's not a connection issue. Everything is cleaned and tight. And I don't think I can replicate the same connection issue with 2 batteries.
     
  16. Nirosorin

    Nirosorin Junior Member

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    Both batteries are able to jump start the car, with the other battery installed.
     
  17. bisco

    bisco cookie crumbler

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    it just doesn't make any sense, there's nothing beyond the fuse but a big cable. how about the connection at the jump point?
     
  18. bisco

    bisco cookie crumbler

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    you might be the first to mod a battery under the hood :p
     
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  19. Nirosorin

    Nirosorin Junior Member

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    Yeah it would be quite a menaj a trois of batteries
     
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  20. Nirosorin

    Nirosorin Junior Member

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    I haven't touched that, except from my jumper cables. Don't see how I could have break it.
     
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