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Reverse Polarity Jump Start - Gen3 Prius wont Start

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Sergey K, Jun 19, 2015.

  1. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Well, the problem will be when the OP finds that link is dead. Then I think he will have to remove the relay/fuse box for access to the bottom of that link.

    Or, is it possible that if he removes the bolt at Terminal A, that is the other end of the fuse link which can be snaked through?
     
  2. jdcollins5

    jdcollins5 Senior Member

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    I think you are right. Terminal A is where cable from Inverter DC/DC connects. The 1E connection goes back to the 12V battery. So the Fusible Link looks like it is between A and 1E, which is probably under the relay/fuse box as you say.

    The Repair Manual just says if Fusible Link is open, to replace it but does not show how.
     
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  3. jdcollins5

    jdcollins5 Senior Member

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    IMG_0217.JPG

    Find attached a picture of the relay/fuse box.

    It looks like the metal piece under the bolted connection could be part of the fusible link but I cannot tell without removing the bolt.

    The white cable to the right that plugs in goes to the 12V battery.

    The cable under the bolt goes to the Inverter module and connects to the DC/DC circuit.
     
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  4. LostViet408

    LostViet408 Junior Member

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    Well, most likely I believe the problem is a burnt fusible link. It can be either the engine compartment, kick panel or the rear positive terminal, but the positive terminal looks good, then I would check the other 2. I think it's bolted down as well.
     
  5. CR94

    CR94 Senior Member

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    Or maybe finds the fusible links are all OK, but a few much more expensive components are dead.
     
  6. bisco

    bisco cookie crumbler

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    let's hope not.
     
  7. SageBrush

    SageBrush Senior Member

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    No doubt complete coincidence if the inverter is fried immediately after a jump start.

    Liar, liar, pants on fire.
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Cautionary tales about being REALLY sure to not reverse jumper cables aside:

    If it's the case that a cable reversal can destroy $1000's of fragile electronics, is Toyota remiss? Is is possible for them, at reasonable cost and complexity, to protect against this?
     
  9. bisco

    bisco cookie crumbler

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    good question. is it possible for them to keep the 12v from draining if you leave the dome light on?
     
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  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The inverter frequently will fail with a reversed polarity jumpstart because the inverter output transistors will be shorted out when negative voltage is applied to the positive battery terminal. To protect against that would require an inline diode in the inverter output which can withstand 125A current flow. Further, having the diode inline would reduce the output voltage by 0.7V. Hence this would not be an elegant solution.
     
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  11. Sergey K

    Sergey K Junior Member

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    Thanks to jdcollins5 post with the image and resistance value, I pulled out the white cable and sure enough the resistance check failed between 1E and A points. The next problem was to actually find where the fuse or the fuse-able link actually was as I was not able to see it anywhere from the top or the sides.

    After over 2+ hours of disconnecting as much wires as I could from the fuse box, or sorry, sorry I meant the "Engine Room Junction Box Assembly" ;), I was able to pry the fuse box up high enough to look underneath. This was A BEAR to do and I hope no one ever has to go through this. Sure enough, there is a 125A fuse attached with two 8mm screws way under the fuse box that connects the 1E and A points from the image above. After shining a flashlight on the fuse, it was definitely blown.

    The next problem was was that one of the two 8mm screws that held the fuse in place was covered up and inaccessible. I had to literally pry the fuse box assembly into two pieces. The fuse box plastic assembly is made up of two pieces, the outer edge slides on top of the inside area. There are small wedge lock clips around the "inside area" of the fusebox. I had to get a standard screwdriver and pry one at a time to separate the two pieces. Even after all the separation, the two pieces of the fuse box would not completely split in two due to all the attached wires underneath holding them together due to space/clearance. I just separated them enough to get to the fuse screws.

    I've now removed the fuse. The next problem is trying to find a replacement as it's not a typical fuse. I'm going to call the Toyota dealer and auto parts stores. Today being a Saturday, I may not be able to find one until Monday unfortunately. Praying that nothing else is wrong. I'll keep you all updated. Pics also coming soon.
     
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  12. Sergey K

    Sergey K Junior Member

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    Here is a side view of the fuse box pryed up showing the hidden 125A fuse. It is underneath the fuse box almost near the center. It's VERY difficult to get to.

    20150620_122734.jpeg

    Here is a close up view of the fuse itself. The right 8mm screw is not accessible until you pry the fuse box into two pieces.
    20150620_122629.jpeg
    I hope this info helps someone in the future. I'll keep you guys updated once I find this fuse replacement.
     
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  13. DoubleDAZ

    DoubleDAZ Senior Member

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    Hope you find a replacement fuse and that solves your problem. If nothing else, we're getting an idea of why some repairs cost so much. I have a Dodge truck with a $28 heater part that costs over $600 in labor to replace. I had it replaced once and it broke again 18 months later. Fortunately, I live in Phoenix, so I may never replace it again. Good luck!
     
  14. Former Member 68813

    Former Member 68813 Senior Member

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    Sergey, strong work! thanks for the pictures. i'm sure this will help some other people down the road.
     
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  15. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Please take and post a photo of the fuse after it has been removed from its socket.
     
  16. jdcollins5

    jdcollins5 Senior Member

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    Ditto to the above.

    Thanks Sergey.
     
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  17. bisco

    bisco cookie crumbler

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    this may be the first time this has been diy'ed. great job. and thanks to all who helped, especially jd.(y)
     
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  18. LostViet408

    LostViet408 Junior Member

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    So I was right about the fuseable link good find sergey
     
  19. Priusguy78213

    Priusguy78213 Junior Member

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    Sorry to hear about the battery issue; I hope you get it resolved soon. Just my opinion, probably less grief to just bite the bullet and take it to the dealership. You could spend lots of time and effort trying to troubleshoot and probably still end up having to take it to the dealership. Keep us posted on the outcome and best of luck with it.
     
  20. Sergey K

    Sergey K Junior Member

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    So no dealerships or auto part stores had this fuse in stock. It's a specialty Toyota only fuse as it has two "ears" sticking out on the sides where those two 8mm screws go into. Ordered one that should arrive on Monday afternoon for $15 at a local Toyota Dealer.

    FYI, for those who recommend just taking it to the dealership, this car has a branded title from a light fender bender about 2 years ago and it's out of warranty. Even if it was in warranty, I believe the dealer would still charge me a ton for all the repairs due to "user error" as this particular fuse doesn't blow on it's own.

    Thanks for everyone's help and input, especially Patrick Wong and jdcollins5! You guys rock and are very knowledgeable. I'm new to this site and will definitely be a regular here now as I have two Prius's.

    Again, I will update you all on Monday or Tuesday and I'll upload a pic of the fuse itself per PW's request sometime soon.
     
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