100Amp DC/DC Fuse Fusible Link Replacement - 15 Minute Job

Well... maybe 45 minutes the first time around.

I recently purchased a used 2009 Prius Hybrid, and it only took me one week to reverse polarity jump across the jumper points under the hood. I've since spent 18 hours or so, researching the Gen2 Threads and Posts related to my issues. Eventually confirmed my 100Amp DC/DC fusible link was blown. I was misled by a couple of posts on this topic, that a blown 100Amp fuse would be very visually apparent. It may be for some, but not with mine. Only after testing all the drivers side under dash junction box (fuse box) fuses and confirming there was no power to any of the fuses with the 12volt auxilliary battery connected, and then reviewing the wiring diagram for the power feed to that fuse panel, did I know for a fact the 100Amp fusible link was toast. I then went back and examined it closely, and could see the small separation in the fuse (like a 1/32" gap where the wire was separated).

I didn't really find any straightforward cook-book replacement thread in the Gen2 Forum. It could be there, but my searches never led me to a thread with good photo illustration and discussion. What I read here led me to believe I could expect to spend ~4 hours changing out this fusible link. So before tackling this job, I went to YouTube and found two videos covering replacement of this fuse on Gen2 Prius. The best of those two videos is titled:
2008 TOYOTA PRIUS FUSE BOX REMOVAL and is dated Sept. 9, 2020. The guy in this video shows how to replace this fusible link in ~15 - 20 minutes. I had my doubts... I I headed out to garage and following his procedure, I had the fuse out in about 15 minutes. If I had to do this a 2nd time, I could do it in about 8 minutes. But I was being careful, still stinging from the reverse polarity jump start.

I took some photos during the process, and will post them here, because I didn't really find much in the way of photos when I searched PriusChat:

This 1st photo shows the 100Amp Fusible Link in the Under-Hood Fuse Box. It's the tall narrow white one on the left side of the photo. I've already removed the red plastic cap that covers that 10mm nut at the upper end of the fusible link.


This 2nd photo shows the passenger side of the fusible link along with the low profile mini fuses attached, after releasing all the small plastic clips that hold this bank of fuses in the junction box, and having pulling the bank of fuses up to clear the shell of the black plastic junction box. This photo is taken from the Inverter side of the junction box, with camera pointing toward the driver side of the engine compartment. Photo taken before removing the 2 - 10mm nuts, one which fastens the copper cable to the side of the fusible link, and the other, which fastens the 100Amp fusible link to the bank of 7.5 - 30 amp mini fuses (to the right of the 100Amp fuse in this photo). They all pull up and clear the junction box as one unit. This provides easy access to the 5 nuts with a 1/4" drive wratchet and the 8mm and 10mm sockets.


This 3rd photo (below) shows the driver side of the 100Amp fusible link, after it's been pulled up from the junction box, and before removing the 3 - 8mm nuts holding three copper cables to the side of the fusible link.


This 4th pic is another look at the driver's side of the 100Amp fuse, before removing the 3 nuts holding the cables to this side of the fuse. Access to these nuts is easy-peasy after lifting the fuse bank up out of the junction block housing.


This 5th photo shows the driver side of the 100Amp fuse after removal of the 3 - 8mm nuts that held the three copper cables to the lower portion of the fuse. Shown in this photo are the two 4-prong male connectors which were plugged into the bottom of the 100Amp fuse. It's a simple matter of depressing a plastic keeper tab in, which holds these two plugs secure to the base fo the 100Amp fuse, and then pulling out / removing the two male plugs. Easy.


This 6th photo wass taken after one of the two white male plastic wire connector plugs had been removed from the bottom of the 100Amp fuse. The second male plug is to the left of the one that's been removed and is clearly visible. These are both 4-prong male connectors.


Maybe this will help someone else. On my 2009 Gen2 Prius, removal of the 100Amp DC/DC fusible link was a very simple and straightforward job. Be sure to disconnect the HV battery and the auxilliary battery before tackling this job! Between the YouTube video, and these pictures, a person with limited tools and experience should be able to swap out this fuse, from beginning to end, within ~45 minutes. And that's proceeding at a slow and cautious pace. Not sure why it's been presented as such a difficult task in the Gen2 Threads and Posts I found and read. Now I can't speak to the Gen1, Gen3, or other Prius vehicles. Only my 2009 Gen2.

Will be a week or two before I learn if I fried the Inverter, because I won't receive my replacement 100Amp DC/DC fusible link until then. That's the one that's gonna hurt, if it needs replaced. Will probably look to buy a used Inverter, rather than purchasing a new one?

I located one 2-minute fast motion video of a Gen2 Inverter replacement within the PriusChat Gen2 Forum. I also quick-searched YouTube, but didn't find much more there. If I have to pull and replace the Inverter I'll search further. That will be a big-time bummer. Enough self-induced pain already!

 

Thanks guys. So I checked all the rest of the fuses, and found 3 more that were also blown.

1) the 5A mini-fuse on top of the 12V auxilliary battery (next to the 120A fuse),
2) the 10A - ETCS fuse in the engine compartment fuse box, and
3) the 15A - Dome fuse in the engine compartment fuse box.

Look's like used Prius Inverters are prolifically auctioned on eBay. Prices ranging from $175 - $275. None (or very few) of the sellers are posting how many miles were on the salvage vehicles at the time the Inverters were pulled for re-sale. So a real crap shoot. Sellers mostly all state the Inverters were tested functional, and commit to 30 - 90 day return warranties, whatever that means. How they test them I haven't a clue. If I could test my Inverter, I would. I think it would require some very special purpose and specific electronic testing equipment. I presume their functionality test may be as simple as having some knowledge that the salvage vehicle was running when they aquired it...

I do a lot of my own auto repairs. Every new-to-me vehicle requires another educational effort. I got started on the wrong foot with the reverse polarity jump on my Prius. At first blush, the Inverter replacement doesn't seem too difficult or complicated. Hope that's the case, should I have that need.

Is there any way to edit my original post? As you know, my first thread/post. I can't find an edit option. Anyone know how editing works on Priuschat?

 

Thanks. That's encouraging information. I could use some encouraging words right now!

 

Thank you. That could very well be why I find no edit option. Will see what happens after my 5th post. If I fried the Inverter, I'll accumulate 5 posts in short order. If I have to change it out, I'll post about that process, and how it went for a home mechanic.

 

This post is likely 'TOO MUCH INFORMATION' for most members, but might help others that reverse polarity jump start their vehicle and blow their 100A DC/DC fusible link.

Below is a Power Source (Current Flow Chart) for a 2006 Prius, which helped me troubleshoot my blown 100A DC-DC fusible link.


Here's the continuation (the right half) of that Power Source (Current Flow Chart):


I didn't know how to interpret rjparker's diagram in his post above, but I see a total of ten (10) separate fusible links in my 100A DC/DC fuse. 5 on the driver's side, and 5 on the passenger's side. I blew the first one on the driver's side, the one closest to the power supply cable coming from the 12V auxiliary battery cable, which connects to the 100A DC/DC fuse under the 10mm nut on the top of the fuse. When the 100A DC/DC fuse blows at this location (see photo of my blown link in the below photo of the top of the 100A DC/DC fuse), it takes out the entire driver's side bank of the fuse. Four additional fusible links on the driver's side bank are visible in the photo, to the right of the blown fusible link. Current flow is from the 10mm nut/post at the left, to the right, down the driver's side bank. The passenger side bank of my 100A fuse has 5 fusible links, and they all remained intact.


Now a photo of the bottom of the 100A DC/DC fuse. The driver's side bank (the side that blew on my fuse) is closest to the camera, the passenger side farthest from the camera. Three copper cables bolt to the driver's side bank with 3 short 8mm headed bolts, and four (4) flat male prongs (all visible in the photo) connect to four wires thru the two white female connector plugs. Four (4) flat male prongs on the passenger side bank which plug into the two white female connector plugs are also visible in this photo.


Based on my Power Source (Current Flow Chart), I have highlighted within yellow, the only fuses supplied power (and protected) by the 100A DC-DC fusible link in the diagram rjparker posted above:

 

Me? Can't see? Hah!
Believe it or not, I have cataract surgery scheduled next week.

Actually glad that brought this up, because I opened up the gap on the blown fuse element using that small screwdriver seen in my Post #13 photo. I did that because the gap was so small I was concerned it might not be apparent in a photo. So to be clear, the gap in my blown fuse was actually tiny. I looked at the fuse several times without seeing it. My estimate is the gap was about 0.015" wide. If I had removed the plastic cover from the top of the fuse, it would have helped me see it. The plastic cover was removed prior to taking that photo.

Thanks much for the offer for a replacement fuse. My replacement should be here in two days. Anxious to see how it goes after installing it.

 

Well I received my used replacement 100A DC/DC fusible link. Here's a photo. Can we see the problem? Just to the right and above the 8 of the 08? Yup, a blown fusible link in a different location. Easier to spot this one. This blown link fed power to the first male tab on the driver's side bank. So they do indeed blow at other locations. This fuse is headed back to the seller for return/refund, and it's gonna be a while longer before I get a replacement and test the Prius out. Bummer...

 

TMR-JWAP,
You wanna sell me a good, used 100A DC/DC Fusible Link? I tried to "start a conversation" with you, but that feature isn't functional for me. Perhaps you can start a conversation with me, and I'll then be able to respond to you in conversation. I did some research and the "Start a Conversation" feature isn't working for many Priuschat members.

If that doesn't work, I can post my e-mail addy here, and you could send me an e-mail? Thanks,
Paul