Prius technical

Is this after trying to perform a health check on all ecus?

 

Did you try to check it on Ready or Acc? Try both. What info does health check give on it?

 

I can tell you exactly what you have going on, as I'm dealing with it right now on a 2007 across town, or at least what I think is going on.

I went to help a lady with a 2007 that was thought to only have a bad HV battery. Car has been OOC for over a month. Got there and had to climb through the rear seat to pop the hatch due to the 12v being dead.

OK, so there's another 12v battery (group 35) in the trunk with jumper cables going to the original 2007 12v battery positive terminal clamp. The positive terminal clamp had been removed from the OEM battery and was sitting to the side. Yes, the OEM 12v from the day the car was built was still installed. It had the negative cable still connected. The group 35 battery had it's positive terminal connected to the negative terminal of the OEM battery and the negative terminal connected to the (hanging loose) positive clamp assembly. Both batteries were completely dead at <1volt. The group 35 was connected to the car with the jumper cables reversed, and had apparently been that way for a few weeks.

I installed one of my spare 12v Prius batteries. Car acts like it can't see the brake pedal being pressed, so it never actually ever gets to ready. The MFD never turns on and the dash never turns on. I can press the power button twice and get online with techstream, but I also can't communicate with the same ECUs you cant communicate with. I found the dome fuse blown plus two others in the engine compartment fuse box. Even after replacing them, still no dash, except door ajar if the driver door is open and the CEL, with communication faults. Brake lights do not come on when pedal is pressed. I suspect the main 100 amp fusible link in the engine compartment fuse box is blown also, and maybe I missed some other smaller fuses, causing lack of power at some ecus.

I'll be swinging by there again tomorrow after work to try to get another look at it before it gets too dark.

Luckily, I have a compete 2007 wire harness in the garage so I can see exactly how to disassemble that fusebox to replace that monster.

 

Replaced blown fusible link and full communication restored. Car is back on the road. I'm pretty confident the OP is experiencing the same issue.

 

The fusible link is the entire white plastic assembly on the passenger side of the fuse box. It has a clear plastic cover. The portion of the link that usually blows is at the upper driver corner of that assembly, but there are several 'fusible' paths.

The fusible link assembly can be replaced from the top of the fuse box. There's some videos on youtube. I found it makes it very easy to pull out if you use a small screwdriver to push each lock tab back and then stick the end of a zip tie into the gap to keep it from re-engaging when you release it. The fusible link assembly and the small fuse assembly below it have to be lifted together. Once all the tabs are held out of the way, you just need to wiggle it upward. Then disengage the fuse portion by removing side bolt and lift it out of the way. 10mm hex head bolts on the passenger side and 8mm on the driverside. I marked all the bolts/lugs with a sharpie to make certain I didn't lose track of where each was connected.

 

Yes, all the Gen 2s use the same block. Now I have something else to keep an eye out for when exploring salvage yards. It looks like this:

 

I should add, that the one I linked is not for a Prius, but it's very similar.