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Blown AM4 (??) fuse

Discussion in 'Gen 2 Prius Technical Discussion' started by JamieLF, Jul 3, 2019.

  1. JamieLF

    JamieLF Junior Member

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    Heya Prius Pals!

    I have a 2007 with roughly 79K miles. She's been with me for about 3 years now, single owner before that with solid maintenance records.

    Was driving the other night, going about 45 mph and the mfd went dark, radio turned off, all dash displays went dark (no speedometer, odometer, etc.) and I had no power steering. Managed to coast into a gas station and a tow truck came to take her to the shop. My headlights and emergency flashers still worked, and the blinker lights on the dash still worked, but she would not start even if I put the key in the slot.

    At the shop, it was determined that I lost power because of a blown fuse- I think they told me AM4 fuse?? Also, the 12V battery was bad, which I kind of figured from reading other posts here.

    So question is this- would the bad 12V cause the fuse to blow or should I be looking for an underlying issue?

    Car had been running fine and was checked out by a mechanic maybe 6 weeks ago and all looked good. I did notice, though, that when I got in the car after work that my mileage was only about 25 mpg. I live in Florida, so thought it was due to car being hot? (I park in he shade and use a windshield shade and keep my trunk cover closed.) Could the bad 12V battery have messed with the cooling system leading to low efficiency and blown fuse??

    Thanks in advance for your thoughts.

    Jamie
     
    #1 JamieLF, Jul 3, 2019
  2. Skibob

    Skibob Senior Member

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    I think you mean the AM 2 fuse and it usually blows if the inverter pump is bad. Search the site here for more information.

    Your 12v is probably dead from using the flashers and towing the car. The battery has a small capacity and won’t go for very long without the car running.
    If they just replaced the fuse and it didn’t instantly blow again and you went on your way, I suggest you get some spare 15 amp fuses and go to your preferred shop to get the inverter coolant pump replaced. It will happen again.
     
    #2 Skibob, Jul 3, 2019
    Last edited: Jul 3, 2019
  3. edthefox5

    edthefox5 Senior Member

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    And when that pump fails you'll never know till the fuse blows and that means the pump is shorting out. Problem with pump not working well is that's the cooling pump for the inverter and the trans and they are getting extremely hot without that pump working. Both very expensive.

    Put the car in ready open the hood and open the inverter coolant reservoir its the white bottle to the left of the inverter with the black cap. Open the cap with flashlight look inside. The red coolant in that bottle should look like its boiling which means the pump is on and you have good circulation. If no movement in the coolant the pump is dead and continued driving will damage the inverter and or trans.

    Its a very important pump do not use an aftermarket pump buy the original at the dealer online or ebay.
     
    #3 edthefox5, Jul 5, 2019
    Skibob likes this.
  4. JamieLF

    JamieLF Junior Member

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    Thanks so much- appreciate you both weighing in. Fuse is AM2- you are correct about that. Mechanic says that the inverter cooling pump is running, but is recommending that we replace it anyway???? Any other thoughts about what could have caused the blown fuse?? Again, thanks so much for your thoughts.
     
    #4 JamieLF, Jul 6, 2019
  5. Skibob

    Skibob Senior Member

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    The blown fuse is usually caused by a short trim the inverter pump. There are cases where the fuse blows but then runs again, for a short while. Get the pump changed, and use a Toyota Factory pump not an aftermarket one.
     
    #5 Skibob, Jul 10, 2019
  6. eljefino

    eljefino Junior Member

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    I've lost my inverter pump on my 05 and fuse and it's awful as far as making the car appear super-dead.

    There was an open recall on my car and Toyota would have fixed it for free. Also one for unhardened steering shaft splines. You can look your VIN up online to see.
     
    #6 eljefino, Jul 14, 2019
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