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No start, no nothing!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Martinf, Feb 20, 2024.

  1. Martinf

    Martinf New Member

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    Hi all,
    New here and new to Prius (tho I'm a subaru mechanic).

    My daughter has a 2008 and she's stranded. She said she went to start her car that the fob won't do anything...no door lock unlock (fortunately the door wasn't locked, no lights, no start. Dead.

    I thought maybe it was the battery bad in the key fob so she put a new one in, but still nothing.

    She's in Seattle and I'm 3 hours away, so I can't diagnose. Any suggestions as what to try to fix or further diagnose would be greatly appreciated.

    I guess I'd start with the 12v battery...I suppose it could be dead...but that conepletly dead as to do absolutely nothing seems weird to me as she drove it last night (tho, she did say that it felt like the fob has been a little irratic lately)
    Thanks for any assistance.
     
  2. JC91006

    JC91006 Senior Member

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    There is a keyslot in the dash, just plug the keyfob into the slot and it should start.

    If it doesn’t start, then you probably have a drained 12v battery. Just need a jump start
     
  3. Martinf

    Martinf New Member

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    Tried the keyslot...nada. not even dome lights or engaging door locks. So you would think 12v battery, but seems weird that it would just go so completely dead overnight.

    I'll get over there, jump and then take a charging volt measurement. If that's above 13, I guess I'll just assume the battery failed and replace it. Thanks.
     
  4. JC91006

    JC91006 Senior Member

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    The battery can drain if a light was left on. Also if the battery is old and weak, it would even drain faster.

    If someone has AAA or a friend can jump start the car, that would save you a long trip. AAA may even replace the battery at car's current location
     
  5. rjparker

    rjparker Tu Humilde Sirviente

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    Not weird at all. The 12v battery is one of the most common things that can go wrong in a Prius.

    First the agm battery is small and lacks the capacity of a regular car battery that has to crank 200 amps to the starter.

    Second your old Prius battery could now be limited to 20% capacity even when fully charged. It can still work enough to boot ecus. In the past I have started a Prius with a worn out 4 amp hour alarm battery.

    But add one hatch light left on because the two stage latch was not closed all the way and you discharge from full to empty overnight. A jump and 30 minutes of driving charges the 20% battery capacity to full. It might be flawless for two months of driving every day. Until the day she just parks it at the grocery and it won’t start 30 minutes later.

    You can load test the battery but cheap electronic testers are unreliable. In your case it would probably fail the battery regardless.

    If the battery is 5-8 years old, change it. I would not chance it for my daughter. Consider getting an oem version which has a far superior warranty because of its quality.
     

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    #5 rjparker, Feb 21, 2024
    Last edited: Feb 21, 2024
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  6. Tombukt2

    Tombukt2 Senior Member

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    Yuasa. Micro AGM .that's a battery
     
  7. Danno5060

    Danno5060 Member

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    Probably what @rjparker said. It sounds like the 12V accessory battery. Being a Prius, it has less than half of the capacity of a normal car's battery, so it's easier to drain. (I gave my wife the birthday present of having her car detailed. They didn't put on a battery maintainer and flattened the car's battery while they cleaned the interior.)

    It's a pain to get to, especially since it's a 12V circuit that unlocks the trunk.

    There's a 12V battery access point inside the fuse box though. Open the hood and pull off the cover to the fuse box (driver's side above the wheel well). There should be a red cover over the 12V battery positive. Flip that to the side and measure the voltage between that and a vehicle ground. That's as good a place to hook up a battery charger as any.

    Since it's a smaller battery, I wouldn't recommend giving it 100 amps like you could for a dead full-sized car battery. I've got a 6 amp charger, which peaks out at 10 amps before tripping out. It's enough to get the battery back to life after a couple hours or so.

    Be warned, a Prius with too low a charge on the 12V battery can be a LOT worse than one with a dead 12V battery. When you step on the brake and push the power button, that's the time when the car draws the most current from the 12V accessory battery. It draws a bunch (relatively speaking) of current for the brake and steering boosters as well as powering up all the rest of the 12V systems. A near-flat 12V battery will lose enough voltage at that point to where it can't complete the power-up cycle, so it crashes - then starts powering up again - and crashes... leaving your car in a long-term powering up, crashing, powering up, crashing... cycle.

    Maybe the best thing to do after you get a charge on your battery will be to open the trunk. At least that way you can disconnect the 12V battery if you get into the cycle.

    At least that's been my experience with a low 12V battery.
     
  8. Tombukt2

    Tombukt2 Senior Member

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    Best thing to do with the Prius is put one of those power sports charging cord adapters on the battery when you install it drill a little hole and you can stick that wire head plug or you can easily access it by reaching on the inner side of the rear quarter panel pulling on it attaching your cord turning on the charger and walking away with your charger and your cable that close to the battery You can give it 20 amps for about 20 minutes and that'll get it up pretty good
     
  9. Martinf

    Martinf New Member

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    All very helpful info and I appreciate you all taking the time to write it. I'm more confident, based on what you've said here, that it is the battery. I'll confirm charging, perhaps do a quick load test, but really just replace and not gamble with it (like I absolutely would if it was my car and my shop available). Thanks.
     
  10. mr_guy_mann

    mr_guy_mann Senior Member

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    All good advice above. I work on a number of Gen2s. The only parasitic draw problems I have seen are tailgate not fully latched or a map light left on. Normal key off draw is around 15-20mA.

    Toyota battery is very good. I have had good results with AGMs made by East Penn manufacturing (sold by Deka, Federated Auto parts, and I think Napa)

    Posted via the PriusChat mobile app.
     
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  11. Tombukt2

    Tombukt2 Senior Member

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    Deja and Yuasa are the gold standard in batteries or have been Deka is well known all my power sports stuff has Deka
     
  12. AzWxGuy

    AzWxGuy Weather Guy

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    We still don't have a post measuring the battery voltage. That would tell a lot. A weak battery will still provide some indications, such as dim interior lighting. The no, nothing, is characteristic of another possibility. The battery grounding strap that connects below the hatch lip. Loosen and reseat that also.
     
  13. Martinf

    Martinf New Member

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    Hi all. Just wanted to report back. The 12v battery was completely dead (a volt or 2). Don't know if it was because my daughter left something on ans it drained it--she says not-- or the battery crapped out.

    Being she lives in Seattle and me 200 miles away, I choose not to mess around with recharging and monitoring the battery (like I definately would have had it been my car) and just installed a new one.

    It was a little tricky because I had to get enough charge on the old battery in order to be able to open the hatch. Grrr. Used the jump point and got it opened. New battery and all done. I did have a few codes, including death triangle I had to clear, but now it's all good. Thanks all for your help.