Help! 2006 Prius won't start, 12 volt battery and fuses good

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by JFoxPrius, Jan 1, 2018.

  1. JFoxPrius

    JFoxPrius New Member

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    Hello, this is my first post. My 2006 Prius won't start and nothing is powering up. The 12 volt battery was replaced less than a year ago. I pulled it out of the car and it was reading at 12.93 volts. I checked all of the fuses and they are all good. I put the 12 volt battery back in and the car still will not start. I measured the voltage of the jump terminal inside the fuse box and it was reading at 3.9 to 4 volts. With the key fob inside the slot the car will not start and no lights are coming on. The only noises that I get are clicking noises coming from what sounds like the relays in the fuse box.

    This started last night when it was driving fine. I pulled up in front of my house and turned the engine off like normal, but it shut off more abruptly than normal. It sounded like something went wrong when I turned it off and the check engine light came on when I pulled the key fob out of the slot. After that it would not start and the check engine light remained on. I decided to disconnect the 12 volt battery until I had more time to work on it this morning. After checking the 12 volt battery and re installing it, the car will not start and no lights including the check engine light will come on.

    I am very confused. Any help will be much appreciated.

    Thank You
     
  2. frodoz737

    frodoz737 Top Wrench

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    "I measured the voltage of the jump terminal inside the fuse box and it was reading at 3.9 to 4 volts.".

    Can't speak for Gen II, but on my Gen III 2010 I read Battery Voltage >12VDC from the jump terminal under hood to ground. You need to get the engine light fault code.
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I assume that you are measuring voltage from the jump terminal to unpainted metal, such as one of the nuts on the strut tower. If this assumption is not correct, please do the voltage measurement again.

    If you still measure such low voltage at the jump terminal, then check the tightness of the battery cables, especially the negative cable where it bolts to the body. Make sure that there is no corrosion or physical damage to the cabling.
     
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  4. JFoxPrius

    JFoxPrius New Member

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    I'm pretty sure the code was cleared when I disconnected the battery. Do you think I should try to jump start it, and see if the check engine light comes back on? I don't know if I should try to jump start it when the 12 volt battery is reading at 12.93. What does it mean when the jump terminal volt reading is low but the battery is reading as basically new?
     
  5. frodoz737

    frodoz737 Top Wrench

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    I always hesitate to tell Prius folks how to T/S because most don't there way around a wrench. But...given the info you gave that I quoted...I believe Patrick is pointing you in the right direction. If the weak link is "after" the battery, a jump won't fix anything.
     
  6. JFoxPrius

    JFoxPrius New Member

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    I double checked the jump terminal voltage and it's reading around 4.5 volts. I checked the tightness of the battery cables, and did continuity test on the negative battery cable and everything checked out. There is no visual corrosion or damage to the cabling. I put my multi meter on the battery terminals with the clip in wires still connected and it was reading at 4.5 volts. When I removed the clipped wires the voltage reading went back up to 12.53 volts. I put the positive probe of the multi meter inside of the positive battery terminal clip on housing, right on the metal piece and the negative probe on the negative battery terminal and the reading came out 12.53 on both the terminals where the wires connect to the clip on housing.

    I am still confused as to what is wrong. I am going to try connecting a portable jump start device to the jump terminal and see what happens. The problem doesn't seem like it is the battery. It seems like it is the connection from the battery to the fuse box jump terminal.
     
  7. davecook89t

    davecook89t Active Member

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    When I measure the voltage at the jump points under the hood of our 2007, I will often get voltages much less than 12V, depending on how forcefully I stab the grounded bolt with my probe. After 10 years, that exposed metal seems to get a pretty good layer of crud on it. Are you getting a consistent 3.9 to 4V when you measure there, or does it jump around a lot?
     
  8. JFoxPrius

    JFoxPrius New Member

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    Yeah it is consistently around 4.5 volts, and surprisingly not that dirty. I am going to take my 12 volt battery to AutoZone, where I got it from, to be tested and charged. The voltage of the battery has dropped to around 10.88 volts after trying unsuccessfully to jump start it with a portable jump start device.
     
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  9. davecook89t

    davecook89t Active Member

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    It sounds like that battery may be a little weak. I have a jump kit that instructs me to leave it connected to the battery for 3 minutes before trying to start the car, supposedly to allow time to transfer the charge to the battery. It sounds like your device may actually be drawing charge from the battery. Does it have lights showing that everything is hooked up correctly? Also, to properly measure the voltage on a battery, it is recommended that it be given a time interval with no load to allow what I believe is called the "surface charge" to dissipate (I believe the electrons need time to migrate to the negative terminal, from a layman's point of view). It's true voltage may be something greater than 10.88V.
     
  10. ChapmanF

    ChapmanF Senior Member

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    This indicates that there is an electrical load active in the car that is pulling the battery voltage down to 4.5.

    That suggests there are two problems.

    A healthy, fully-charged auto battery will not be pulled down to 4.5 volts by any reasonable load (in a Prius, any load heavy enough to do that would probably also be making smoke, which would make it easy to find, at least).

    So it sounds like that battery has developed a bit of excessive internal resistance.

    If you know somebody with a clamp-on DC ammeter (not as common or cheap as the AC kind), it would be interesting to clamp over that cable while it is pulling the battery down to 4.5, and see what size current is doing that.

    One potentially reckless thing to try would just be to swap in a well-charged, known-good 12 volt battery.

    One of two things may happen.

    1. The load that was pulling the old battery down turns out to be some normal load in the car (the brake pump, for example), and the good battery just runs it successfully until it shuts off, and all is good.

    2. The load that was pulling the old battery down turns out to be an electrical fault somewhere, that the old battery could not drive hard enough to make smoke, but the good battery can, which would make it easy to find, at least.

    Now you know why I said "potentially reckless." :)

    If it were me, I would try to get that amp reading with the old battery, first.

    -Chap
     
  11. Sam Spade

    Sam Spade Senior Member

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    You likely have a bad main battery connection somewhere.

    This most often occurs at the body/frame end of the negative cable but can occur right at the battery even if those connections look clean and tight.

    First, measure on the cable end connectors at the battery posts (not the actual battery posts).
    If that is OK, then attach your negative meter lead to the negative battery post and measure to the frame.
     
  12. ChapmanF

    ChapmanF Senior Member

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    If the OP really meant the meter probes were directly on the battery terminals here (which seems to be the most literal reading of the sentence), then I don't think I can join in attributing excess resistance to any other connections in the car, but only to the condition of the battery itself.

    Or, if the probes were touching the cable clamps attached to the battery terminals, there could be an issue of bad contact between the clamps and the terminals, but not elsewhere.

    (I actually saw that once in a friend's car; it seemed fine, everything powered up, etc., until you tried to start it; then everything went dark, and stayed dark for five or ten minutes, then lit back up again. It was like there was some crazy self-reset circuit breaker in there for the whole car. It was really just one battery clamp making such poor contact that the starter current would heat it up and expand it, not enough to see, just enough to break the circuit, until it cooled off and got tighter again.)

    But in this case, assuming the OP really meant the meter probes were on the battery terminals themselves and not the clamps, even the clamp connections can't be implicated.

    -Chap
     
  13. JFoxPrius

    JFoxPrius New Member

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    The battery is at AutoZone right now, being charged. The guy at the counter said the battery was not giving him a "bad" indicator, but it said 0% charged. I tested the battery with my multimeter right before bringing in it and it read 11.5 Volts. When I get it back I will try putting it in the car and making sure all connections are solid. I will post the results.

    I'm wondering what could be making the voltage drop to 4.5 volts when I connect the battery to the car. A lot of the other posts on "car won't start with a good battery" tell the person to check the voltage of the Jump terminal. I haven't seen anybody post there results of the jump terminal test. Since my jump terminal reading is so low, that has to mean something. What does it mean when the jump terminal has a low reading but the battery checks out as normal?
     
  14. bisco

    bisco cookie crumbler

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    usually a bad connection or ground. but in your case, i think chap is right. either the battery is defective, or you have a major load on the system, probably caused by a short somewhere.
    how many miles on her?
     
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  15. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Yeah, if voltage at the battery was 12.93, and at the jump point around 4, wouldn't that point to bad connections, not an ailing battery? You could check the battery condition fairly conclusively with an electronic load tester, most battery retailers have them now I think. A DIY version is Solar BA5.
     
  16. Sam Spade

    Sam Spade Senior Member

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    At 11.5 volts it really IS near to 0% charged, and in that case a lower reading well away from the battery might not be unusual.
    I'm wondering why YOU had a battery measurement that was so much higher ??
     
  17. JFoxPrius

    JFoxPrius New Member

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    I just got back from AutoZone and at first they said the battery was not done charging yet. It had been there for almost 3 hours. The guy went to check on the battery and came back saying that the battery had not charged at all, and was still at 0%, after all that time on the charger. He said he would try charging it again and call me when it is done.
     
  18. Sam Spade

    Sam Spade Senior Member

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    And you bought that story ??
    You need a new battery.
     
  19. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    Assessing the battery by seeing how it does on the charger, is not that professional. Most retailers, and dealerships for usre have a pro-quality electronic load tester for checking a battery's health. Basically the big brother of a DIY level Solar BA5. Google that for more info.
     
  20. JFoxPrius

    JFoxPrius New Member

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    It is still at AutoZone and they haven't called back yet. It is one of those yellow Optimus batteries. I bought it at AutoZone less than a year ago, so it should still be under warranty. If it doesn't work, or they can't charge it, I will ask them to replace it with a new one.
     
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