Blown A2 fuse mystery solved

Discussion in 'Gen 2 Prius Technical Discussion' started by Sherlock Prius, Dec 10, 2021.

  1. Sherlock Prius

    Sherlock Prius New Member

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    2007 Prius
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    Two
    My faithful 07 died in a parking lot. No dash lights. Nothing. Checking this site, someone recommended checking the fuses, particularly the A2.
    Sure enough, blown. Got a pack of 10 amp fuses, plugged one in. Car started as normal. Next time I shut it off, the same system failure.
    Checking this forum, someone said the A2 fuse failure likely caused by inverter cooling pump failure.
    How could this be, I thought. I just changed it a year ago. And when it failed then I got the triangle of death and a code that pinpointed the problem. No such warning this time.
    Anyway, I managed to unplug the electrical connection to the pump, put in another fuse and drive 15 minutes home. Cool day, fingers crossed the whole way. Made it!
    Despite not having the same warning as last time, I figured the problem was another bad inverter cooling pump because they ar so prone to failure.
    Changed it out a week ago and I’m back in the game!
    Tips:
    Definitely take out the left headlight. So much easier to swap out the pump.
    And if your coolant drain plug doesn’t want to come out, remove lower coolant hose and drain. Don’t forget to bleed system. I gallon of Asian HOAT coolant needed for the swap and drain.
     
  2. dolj

    dolj Senior Member

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    Did you mean the AM2 fuse?
    Was this replacement pump OEM?
     
  3. edthefox5

    edthefox5 Senior Member

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    Very very common.

    Fuse blows because when the inverter coolant pump fails
    many times it shorts out and blows the am2 fuse.
    If you had used the search form link up top and searched
    AM2 FUSE
    there are hundreds of posts about it all pointing to a bad pump.

    And not sure what you mean about removing a hose to drain it. You must remove the drain bolt in the trans to drain all the inverter coolant loop which is the big inverter aluminum cooler and trans. So if you removed a hose above that you did not drain the system.

    The factory oem pump is very high quality and will last many years the crappy pump they sell at auto parts stores does not. I lost a pump that lasted 100k miles before it failed and was able to limp 5 miles to get car to a safe place without blowing the fuse. You probably cannot do that with a junk pump.
     
  4. alftoy

    alftoy Active Member

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    Why does a failed OEM pump allow you to limp 5 miles without blowing a fuse versus an aftermarket pump.

    Interesting, I did buy a spare OEM inverter pump, may have to store it in the car with some fuses and coolant.
     
  5. edthefox5

    edthefox5 Senior Member

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    Because a OEM Denso pump is much higher quality than the Chinese pump you have. And twice the price. And worth it.

    That pretty much goes for any auto part you buy from an after market parts store. Not to mention the huge counterfeit issue parts now have.
    For instance you buy sparkplugs from rock auto or Amazon really good chance there counterfeit. Box looks really close too.
     
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