No power except brakes and brake lights, HELP!

I have a 2006 Prius. One morning I just went out to start it and nothing. No lights, even the dome and headlights won't come on. No screen no dash lights, even hazard lights don't work. When I press the brake I can hear the brake booster come on, and the brake lights also come on. That's it. Nothing else works. 12v battery is under a year old, reading 12.9v on the multimeter. I took it out and tested it, tested fine. Charged it up before putting it back. Still nothing. Checked all fuses, all fine. Checked power under the hood under each fuse/relay and at main terminal and reads same as battery, about 12.9v. Yes the battery is hooked up correctly and has never been in reverse polarity. No physical damage to any wiring (from rats or anything) that I could find under the hood. What is going on here? I can't even read codes off this thing, completely dead except for brakes! Any ideas? I am easily over an hour drive from the nearest toyota dealer and almost as far from any repair shop so getting it towed will be expensive, but I'm pretty handy with cars. This hybrid is kicking my behind though.

 

Thank you for the reply. Yes ECU harness is getting power. Everything is. I tested at all fuses/relays/harnesses that I could access. Removed whole dash and a bunch of stuff under the hood to test all connections and referenced service manual to see what's supposed to have constant power. Everything is getting 12.9v. I even swapped the battery out with the one from my other car just for giggles. Nothing. I'm completely stumped. Only brake booster and brake lights. Nothing else works. No locks, not even the dome lights. Replaced key fob battery just in case as well but still nothing, though I believe the dome lights, locks, and headlights should all work even without the key present. I talked to a Prius mechanic this morning and he says what I'm describing is impossible. I agree, but it doesn't change the facts. I was up all night working on this because I'm in South Florida and the car is parked outside (HOT). I'm very close to calling a scrap yard and having the thing towed away. I know any diagnostic at a dealer + tow is going to cost me more than the car is worth.

 

Yeah AM2 is one of the first things I checked. Good continuity. I replaced it anyway. It's getting good power and fuse isn't blowing. I didn't think the inverter pump had anything to do with this...could it have blown any other fuse besides AM2? I mean I checked them all anyway (I think) time and time again but at this point I'm willing to try anything. Maybe I'll disconnect the pump anyway. Is pulling the relay enough?

 

I agree, that's why I posted here. And everywhere else. Someone on Facebook suggested I pull out the orange plug and beat it against a tree, blow in it, and plug back in. I just tried that. It didn't work. I spent all day and all night taking off every panel and testing every harness, relay, fuse, etc according to the factory service manual, worked front of car to back of car. That's what I did. Also ruled out the battery, definitely not the battery. All systems that should have 12v when the car is not on do, and I can't turn the car on so I can't really check any further than that. OBD port provides power but nobody is home. Scanner can't connect, likely due to the fact that the car won't turn on. Also I jammed the hazard light switch in a bit harder and the hazard lights do work now. I think my hazard light switch is getting a little unresponsive and that's why I didn't notice before. I don't use them often. Been trying to hire someone to come out here and look it over and find that one stupid obvious thing I missed (I agree with you on that one) but I live so remote that so far nobody is willing to come out, and towing to the nearest shop will be as much as the car is worth. So I'm doing my best to describe what I've done, but at this point I'd have to write a book, and who would read it? I was just hoping someone out there encountered this before with all the Prius out there and at least point me in the right direction.

 

What does Florida Positive mean? And yes anything is possible, I'm not taking anything off the table. I'm starting to wonder if I have a bad ECU or something. I know most of the switches don't go directly to a load but rather are serial connections and switched by a computer somewhere else. I should probably find what isn't controlled by a computer and see if that works. Sorry I'm new to Prius. I haven't owned this thing very long and it's my first hybrid and first time trying to fix anything on a hybrid. I'm more of a old pickup truck kind of guy.

 

Now you're thinking! I will try it in the morning and report back.

 

There's the main and the little 5a blade fuse on the + battery terminal. Are you referring to those? Both of those are fine unfortunately, and I'm not aware of any others near the battery.

 

Wow that was super helpful. Thank you. It's funny it's 1am local time and I just sat straight up in bed, woke my wife up, and told her "I have to go check if the horn works". I actually completely forgot to try it. So here I am outside trying to beep my horn at 1am (sorry neighbors). YES THE HORN WORKS! I didn't even know there were "vanity lights" behind the visors. They however do not work. So I've got working horn, but non-working vanity lights. Yes all the fuses you listed are tested and fine. Actually I couldn't find a blown fuse anywhere in the car. I actually checked them with a multimeter too, not just visual inspection. I even put a multimeter to the fusable links in the under-hood fuse box just in case, all that checked out too. Visual inspection of all wires I could find for rat damage, all fine as well. I've been studying the lighting wiring diagrams and troubleshooting procedures since it seems nothing controlled by the body ECU is working. I will dig into that more tomorrow as well. Also, OBD2 connector does have power, but I can't get any codes or data from it since I can't turn the car on. Anyway thank you for the insight on the horn and vanity lights. And yes I do have that diagram. I guess I won't be pursuing the downstream from the horn since that works, but I will see if I can trace back the vanity lights on the diagram.