1. Attachments are working again! Check out this thread for more details and to report any other bugs.

125 amp fuse replacement

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Chabelo, Dec 8, 2022.

  1. Chabelo

    Chabelo Junior Member

    Joined:
    Jul 4, 2014
    24
    5
    0
    Location:
    Valley Springs, Ca
    Vehicle:
    2014 Prius Plug-in
    Model:
    Plug-in Advanced
    Has ANYONE figured out how to replace that buried fuse inside the main box? Is there an instruction in the technical manual?
    (THis is the fuse that blows when reverse polarity is applied during a jump start).
     
  2. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,913
    4,677
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    You have to remove the fuse box primarily from the fender. At that point the top and middle sections can be separated.

    * 125a fuse visible from top.jpg Prius gen3 125a fusible link.jpg Fuse Box top view typ.JPG fuse box right side typ.JPG Gen3 125A fusible link part.jpg
     

    Attached Files:

    bisco likes this.
  3. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    6,044
    3,245
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    What a pain in the butt! I think that if I ever had to replace that thing I'd solder on some this
    wires and mount it elsewhere!
     
  4. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,913
    4,677
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Some have used a bypass but the one I saw had corroded badly and failed again. It has to handle over 100 amps which precludes normal small gauge wire.
     
  5. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    6,044
    3,245
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    Clean up the corrossion, solder 145gauge wire to and external fuse holder.
    Since it's so rare these blow, like someone hooking a jumper up incorrectly, I'm not going
    to worry about it.
    But "if" mine blows, after fixing the problem that caused it to blow, external it is!
     
  6. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,913
    4,677
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    As an academic exercise I've put together the way I would bypass a blown 125 amp if were caught on the side of the road in West Texas with only a NAPA store at my disposal. The tricky part would be finding an appropriate fine stranded cable, either a cheap jumper cable or a junk yard piece of the original white fuse box cable.

    C0488DB7-81C0-4B33-8C82-8831B8C88267.png
     

    Attached Files:

    Mendel Leisk likes this.
  7. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    55,395
    38,635
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
  8. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    6,044
    3,245
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    I have plenty of wire..... And that ground connector....
     
  9. Chabelo

    Chabelo Junior Member

    Joined:
    Jul 4, 2014
    24
    5
    0
    Location:
    Valley Springs, Ca
    Vehicle:
    2014 Prius Plug-in
    Model:
    Plug-in Advanced
    It’s extraordinarily difficult to separate the center section of the fuse box from the main body to replace the 125 amp fuse. I spent an hour struggling with a junkyard piece and basically had to destroy it to get the fuse out.
    I am just going to beef up the bypass method on mine and call it a day.

    as near as u could tell, there are 3 bolts fastening the main body down then a plastic pin that snaps into a hole in the fender. Once the box is free, there are 5 cam/clips that secure the center section to the rest of the box. They have to be simultaneously pressed while you push the center section down. I’m not even sure if you’d have to disconnect ALL the wiring harnesses to gain clearance to separate the box.

    I cant believe Toyota buried a fuse in an un-accessible location!
     

    Attached Files:

  10. Chabelo

    Chabelo Junior Member

    Joined:
    Jul 4, 2014
    24
    5
    0
    Location:
    Valley Springs, Ca
    Vehicle:
    2014 Prius Plug-in
    Model:
    Plug-in Advanced
    In my 2014 pip, the white wire labeled 1e in your diagram is aluminum. The same white wire in a 2010 at the junkyard is copper…
    Galvanic corrosion here we come!
     
  11. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,913
    4,677
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    You can get connectors that work with al and cu. There is also an anticorrosive compound you can use. In any case my scenario would be cu to cu and only temporary.

    Bottom line - use a lithium jump pack with polarity protection - only!
     
  12. Tanager

    Tanager New Member

    Joined:
    Jan 25, 2024
    3
    0
    0
    Location:
    France
    Vehicle:
    2008 Prius
    Model:
    LE
    I don't know if Nyone still needs this, but this is the video I used to replace it.

    Pulling out the block was much, much harder than in the video, but I managed.

    Now my car starts, but only for a few seconds before cutting out, also no interior lights etc brand new 12v... so I needed more than this...

    Best of luck!
     
  13. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,913
    4,677
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    The hard to replace125a is in the gen3 cars rather than the gen2 shown in that video, although gen2 is certainly not plug and play.

    Usually there are more fuses blown.
     
    #13 rjparker, Feb 1, 2024
    Last edited: Feb 1, 2024