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Help with an electric gremlin P0A08 and fusible link

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by SparklePimp, Dec 27, 2021.

  1. SparklePimp

    SparklePimp Junior Member

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    My issues started back in August or September of this year (2021). Get a warning code P0A08 DC/DC inverter issue (NOT P0A80) and through some checking, I get my inverter and inverter coolant pump changed out at a specialist shop. I had my 12V and big battery checked and both are working perfectly. 12V battery was installed May 2021.

    At the beginning of December I start to have some other issues. First being the main coolant pump needed replaced. Then my car started acting up even more. First was to have the 12V battery completely dead in a parking lot where the door would beep 10 times, but not unlock with the key. Changed battery in the FOB and still would not start, but would show lights on the dash. Take it to a Toyota dealership and they decide that it was a faulty brake light switch. I get that replaced and the car now starts and runs. My specialist repair tech said that brake lights not working are a sign of a blown 125 AMP fusible link. More on that later.

    Then the car does it again where it refuses to start. I hold the start button in for 30 seconds and force(?) the car in to aux mode which says "ready" but would not let me put it into gear. The engine kicks in so I leave it be. I let the car run in front of my house for a while and I guess it charged the 12v enough to allow the car to stop and start normally as well as drive. I start getting the P0A08 code again, so I reach out to the shop for a warranty replacement and drive it in. The car dies on the way there with a bunch of lights on the dash as well as the speedometer going to zero. I was able to snap a photo of it while getting myself to the shoulder.

    Inverter #2 is put in and I'm happy to leave. Put the car in reverse and it shuts off with a full array of lights. The tech and I are both confused. He starts looking deeper into the car and finds some rigged up system going on. It was tucked up under the fusebox and I tried to take multiple photos of it.

    The shop that my car is currently at only works on inverter and battery replacements. I have no issue with getting the parts and fixing this myself. Here's what we've found:

    In the fusebox the 12V line in from the battery has been tapped to bypass the 125 amp DC/DC inverter fusible link inside the fusebox.

    An inappropriate buss fuse was put in line from the battery line and is jumped to the inverter terminal in the fusebox.

    Battery line has puncture & possible damage. It appears that maybe someone tried attaching the 12V cable directly to the inverter terminal.

    From what I'm being told from the tech, the fusible link should be under the fusebox. Or it's the long white box with the Toyota sticker in the fusebox? I need to know what are all the parts I should get to fix this. I want to take the buss fuse off and put the proper fuse in place. His theory is maybe someone tried improperly jumping the Prius and thus blowing the fuse. This is an absolute mess, but I really want it fixed. The photos I have show the exposed wires and buss fuse, but when we found it, everything was wrapped in electrical tape and tucked under the fusebox.

    Also, is the 12V cable one long cable that runs from the back battery to the engine compartment? Or are there links along the way that I can replace just the front section? Any an all help is going to be greatly appreciated.

    I live in Orlando FL, but my car is currently in Clearwater FL. I will have to move it off his site because he was nice enough to allow me to keep it there over the holidays, but it's not supposed to be there.
    [​IMG] [​IMG] [​IMG] [​IMG]
     
    #1 SparklePimp, Dec 27, 2021
    Last edited: Dec 27, 2021
  2. bisco

    bisco cookie crumbler

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    how long have you owned her? how many miles?
    are you sure that the 12v and connections are good?
    if the car is in clearwater, i would call todd at tampa hybrids
     
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    What in the world...............
     
  4. rjparker

    rjparker Tu Humilde Sirviente

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    The 125amp fuse is inside the fuse box. It gets blown by a reverse jump. I doubt your issues are the hacked in fuse, but if you want to replace it the ecu next to it has to be removed followed by the fusebox. Then the fusebox is taken apart. I will include a pic where you can see the fuse from the top using a light.

    * 125a fuse visible from top.jpg

    *Fuse box diagram with jump point.jpg

    Fuse box gen3 w view of fusible link.jpeg

    Fuse Box top view typ.JPG
     
    #4 rjparker, Dec 27, 2021
    Last edited: Dec 27, 2021
  5. ChapmanF

    ChapmanF Senior Member

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    Definitely a "thereifixedit" approach to replacing that very-tedious-to-access fuse.

    Once you have the fuse box freed from the body and opened up, that large middle section ("Unit A" here), which carries the fuse, pushes downward from the outer frame, when you release it at five clippy places, which are kind of where the green arrows indicate here.

    [​IMG]
     
  6. SparklePimp

    SparklePimp Junior Member

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    Thank you for the quick response on here. I've had the car since July of this year. It has about 147,000 on it give or take.

    The connectors at the battery itself are clean and tight. I've tested it with a multi tester to confirm 12.8V just sitting there and having it go to (I think) 14.3? when the car was running. This was of course when it wasn't throwing codes at me.

    I actually called Todd before I came on here, but he said that he doesn't touch anything that has been modified and suggested I take it to Toyota.

    My theory is that if the fusible link is supposed to get the 12V AFTER it goes through the fusebox and this hack job is leeching the 12v before, then it might be causing the voltage to drop slightly more than what the ECU tolerates and just shuts it all down.

    I have had codes come in saying brakes, ABS, power steering, main water pump all at the same time with P0A08.

    So now comes the part ordering. I'm sure I can find the fuse no problem. Any idea what the part number might be for the white 12V cable? I'll have to tow it to my in laws in St Pete to work on it there I guess.
     
    bisco likes this.
  7. rjparker

    rjparker Tu Humilde Sirviente

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    It is possible that a badly made crimp connection has corroded on the 125a bypass. There is nothing inherently wrong with a bypass done right. I would also verify all fuses one by one. Don't mix them up or replace them into the wrong slot.

    The 12v current moves from higher voltage to lower (conventional current) and your hacked 125amp fuse does exactly what the factory fuse would do. A bad connection where the bypass connects (four points) would be my only concern. Those points are easily inspected by looking for heat discoloration, obvious loose connections and by measuring for voltage drops across the joints.

    Then the inverter would become my prime suspect - again. These inverters are known to be a flawed design. In fact a new one was available free from Toyota prior to the independent shop's work. In addition, revised inverter software should have been installed.

    The factory white 12v cable is one big harness all the way back to the battery I believe. Most would get a salvage part from ebay or a LKQ type of local salvage yard. I would carefully exam your cable and use it after inspecting the "work" for corrosion. I can't tell if the splice is soldered. If it is a good shiny solder joint it is probably good. Instead of tape, I would use "liquid tape" first, let it dry, then wrap with the good 3M electrical tape. Both available at Home Depot.

    Buying factory parts? Take the vin to the parts department and get the part numbers or just order them. You can also call or email a Toyota online dealer like McGeorge with the vin and usually get a healthy discount.

    This is a 2012 v 125amp fuse.
    11009CE0-83DF-48D0-9C2A-5FF2C60D8C24.jpeg Gen3 125A fusible link part.jpg
     
    #7 rjparker, Dec 28, 2021
    Last edited: Dec 28, 2021
  8. SparklePimp

    SparklePimp Junior Member

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    I'm not sure how right the bypass job was, lol. Looking at the fuse you listed and the picture of the one in the bypass, there's a 2v discrepancy. I'm not sure if that would make any issues arise, but I would rather have the correct value.

    I had contacted Toyota's service line when I was first getting some code issues. The representative told me that in the system, my car had the recall performed at Miracle Toyota in Haines City, but it wasn't "validated". The rep said that it was the final step to double check that the software was correctly installed? I did not get to take my car back to Haines City for them to do that, but the Toyota shop that I had a brake light switch replaced said they would check it for me.

    The splice is crimped on with a metal ring and there is a good amount of solder. It's quite a mess.

    I will be looking for liquid tape and will be buying at least 2 of the fusible links from my local dealership just to have the part faster (if they are in stock)
     
  9. SparklePimp

    SparklePimp Junior Member

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    I wanted to update the thread here. It’s been some time, but a lot has happened that had me without my Prius for a bit (unrelated).

    I did attempt to take apart the fuse box to get to the fusible link, but I had to concede. I wasn’t doing something right, or missing a bolt somewhere. I ended up taking it into Toyota and the mechanic there was able to remove the hack job and replace the fusible link.

    At least I didn’t have to pay for the fusible link lol. Anyways, all is going well, and I have not had a single code come up since the repair.

    I am happy
     
  10. ChapmanF

    ChapmanF Senior Member

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    Thanks for the update!

    Though I didn't see this part at the time, it deserves a little clarification, just for future readers of the thread:

    The amps stamped on the fuse (125) tell you at what current the fuse is designed to blow. It's important to get that right.

    The volts stamped on a fuse are there to keep you from misapplying the fuse at a higher voltage than it can handle. If the fuse is marked 32 volts, and you're using it on a Prius electrical system that never goes above 15, it's fine, and so is another fuse even if it's marked 2 volts higher or lower. Neither one would be misapplied in that case.

    Now, there can be other differences between fuses, like how fast they blow at what levels of overload. But you don't see that info stamped on the fuse; you can usually find a graph with the details if you hunt down a data sheet for that particular fuse. So that's probably the more important reason for going with the fuse the engineers selected.