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Reverse Polarity Jumpstart, Strange Symptoms

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by Boefinator, May 16, 2024.

  1. Boefinator

    Boefinator New Member

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    So....I was in a rush after returning from a two week vacation to find my 2017 Prime Advanced dead. Jumped started using Jeep, but crossed the wires from the donor car. Long story short, the main fuse was fried, same with some fusible links and the dome fuse. Replaced all that and luckily car came back to life.

    But there are persistent issues I can't figure out. When the car is off, none of the 12v systems work. No interior lights, no keyless entry, no power door locks, no remote start, can't connect to the car via the app.

    I have to use the manual key to open the door, the push button start works and the car runs fine. With the car on, the dome lights work, the power door locks work, power windows work, all the driver assist systems all work. The HUD works but the position has to be reset every time the car is turned on and the clock always resets.

    The things that are not working regardless of car on or off is the infotainment system and the buttons on the screen and the QI wireless charger.

    I've checked all the fuses for continuity and can't find any issues. I would appreciate any ideas you may have on this one.
     
  2. bisco

    bisco cookie crumbler

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    did you check both fuse boxes?
     
  3. Boefinator

    Boefinator New Member

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    Yes both engine and kick panel.
     
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  4. KMO

    KMO Senior Member

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    Good puzzle.

    Looking at the wiring diagram, I vote for "10A ECU-DCC NO. 2" in the interior fuse box.

    Edit: Or, possibly, upstream of that, "25A D/C CUT" in the engine compartment fuse box.

    (D/C CUT is the fuse that's removed during shipping, leaving a car that can be driven on and off trailers, but doesn't drain the battery when not being driven. Dealer fits it during pre-delivery inspection).
     
    #4 KMO, May 16, 2024
    Last edited: May 16, 2024
  5. rjparker

    rjparker Tu Humilde Sirviente

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    There are fusible links that don’t look like fuses.

    Since you have devices not working, the straightforward technique is to get the schematic and trace the non-switched 12v for that device using a meter. Find it and you probably find all.
     
  6. Boefinator

    Boefinator New Member

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    I'll put new fuses in both of those. Thanks for the idea.
     
  7. Boefinator

    Boefinator New Member

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    The DC CUT fuse sure sounds like it would cause the symptoms I'm seeing. I checked fuses for continuity, but I could have missed it or just did it wrong. I'll have the car back tomorrow and post the results. I read the DC Cut fuse threads now and that sure seems like it. I appreciate the help.
     
  8. Boefinator

    Boefinator New Member

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    I'm on my way to get a 25 amp fuse, but when in pulled I got other words that popped up regarding the collision avoidance and a yellow exclamation point. So I'm guessing that it's not the DC CUT fuse. I'll also try the 10 amp ECC NO. 2, but it looks good as well. Maybe a relay or a 12v sense circuit that is preventing 12v power going to these systems when the car is off?
     
  9. Boefinator

    Boefinator New Member

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    Indoor fuse box, apparently I didn't check as well as I thought. Thanks for your help.
     
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  10. Boefinator

    Boefinator New Member

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    Winner Winner, Chicken Dinner! Your first guess was correct, ECU-DCC No. 2 restored the power and activated the locks, wireless remote, dome lights, and maintained all settings when powered off. The only thing that wasn't back was the infotainment system. So I figured if I missed the ECC fuse, maybe the 15 Amp Radio fuse I didn't check correctly and what do you know? It was a bad fuse as well. Thanks for your help!
     
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  11. KMO

    KMO Senior Member

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    Now I just feel bad for not having enough confidence to stick with ECU-DCC No. 2. :LOL: I didn't spend the time to check what else DC Cut would have killed... :whistle:
     
  12. Boefinator

    Boefinator New Member

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    It's all good just needed to drive to reset. Thanks again.
     
  13. ChapmanF

    ChapmanF Senior Member

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    Is DC Cut even an actual fuse in a Prime? In gen 3 it's just a shorting jumper.
     
  14. KMO

    KMO Senior Member

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    Apparently.

    Electrical Wiring Diagram says "25A" and shows it with a fuse symbol under "fuses", so I guess that's what it is. Also a fuse in G5, IIRC.
     
  15. RandyPete

    RandyPete Member

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    I think this post is in regardss to a 2017 Prius.
    Does a 2024 Prius Prime have a DC Cut fuse ?
     
  16. KMO

    KMO Senior Member

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  17. RandyPete

    RandyPete Member

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    Had trouble viewing that PDF like link. It seems to need a special app to view. Not willing to Install that app and agree to the use terms on my PC.
     
    #17 RandyPete, May 19, 2024
    Last edited: May 19, 2024
  18. rjparker

    rjparker Tu Humilde Sirviente

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    Pdf
     

    Attached Files:

  19. RandyPete

    RandyPete Member

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    Thank You, I downloaded that PDF and saved it.
    Viewed it. Saw the DC-DC CUT labeled item.
    Unfortunately my experience in reading and interpreting this info is very limited.
    PS: looks like the battery is depicted next to the FB/RB, like the 2022 PP, not the 2023-24 PP arrangement.
     
  20. KMO

    KMO Senior Member

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    So what are you looking for? And what was the reason for the question?

    The point is that there is an amperage value shown for it - 30A - which makes it a fuse.

    The document is covering all model variants. That would be the 1.8L 2ZR-FXE position. The (*1) footnote is presumably noting the model variant.
     
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