Help with an electric gremlin P0A08 and fusible link

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.

 

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.

 

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)

 

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