No Start / Ready - Flashing Gear Lights - No Gear Shift, no CEL

Hey guys. I've got a fun one.

Background:
Drove to the store. Had the car idling for like 20 mins. Not sure it's related, but it's hot here. Pulled onto the road.

1. After 100 feet, the car moved itself into neutral. Weird. It wouldn't shift back into drive or reverse. Nothing else wrong.

2. I turned it off, then back on. Shift into D. No apparent issue. Pull into adacent parking lot, a lot of dash lights flash on then back off including the red triangle. But still drives. I make it about 40 feet, and it shifts back into neutral. Won't go into D or R again. I sit in neutral with hazards on for 2-3 mins then get the car pushed into a parking spot.

3. I wait 1.5 hrs for tow. At arrival, the car will no longer go into ready mode or neutral. Instead the dash turns on like normal, then after ~15 secs, the gas guage and gear indicator lights flash on / off continuously. I attached two photos of on / off. You can imagine it flashing between each. This is now the current state. I have a video, but not sure how to upload.

Current Symptoms:
Red triangle is off.
Can't enter ready mode.
On start, dash flashes (Neutral / Drive / Park / Rev) and Fuel Guage flash on / off
Can't shift into neutral or otherwise.
Can't read engine codes (ODB2 shows no connection). Also, prior CEL light is now off (unrelated exhaust code).
Center screen shows main battery at 0. (Dubious that it's discharged. It showed bars before stopping).
Center screen doesn't show outside temps. Reads as "E" instead of temp.
Pulling / replacing AM2 fuse causes car to power on (lights flash, no ready). This is really weird.

Diagnostics to date:
1. I don't think it's the 12V. I replaced it last spring, so it's pretty new. I tried jumping from under hood, and direct to battery w/ no success. I also messed with the car for like 4 hours, and never had the electronics not function. The wipers work. Windows go up / down. Lights / blinkers work, etc.
2. I tried the AM2 fuse. It looks fine, and I swapped a good one anyways, and no change.

 

Good news guys. I've never been so happy to wake up to a dead battery. I was out of town over the weekend. Went to start working on the car this AM, and no power whatsoever. I threw a charger on, and it cycled off / back on about 4x times in a 2 min window. I pulled it off and am going to see if I can borrow a different charger. Mine's ancient. I'll report back once I get a good test on charging the battery.

Sam: Hoping it's the 12V. I'm no hybrid mechanic. Honestly, I'm no mechanic. I'm an avid DIYer. Below is a post from a prior issue, I've had. That's hopefully a guage for what I can handle.
ECU / Red Light Issues. No Start. - New Prius Owner | PriusChat

Bisco: 110k. Not too many. I've already replaced one ECU (battery), because it burnt up, possibly moisture related too. I'd hope it's not bad again. I have just a cheep ODB2 reader off amazon. Nothing of quality. It often helps though.

MrGuyMann: Helpful to know it's possibly the CAN network. If it ends up not being the 12V, I'll start with some reading as reccomended.

Thanks guys. Prius Chat, as always, is the most helpful.

 

As an update guys: Turns out there were 2 problems. Most of the blinking, etc, was due to the discharged 12V. I charged it, and the car started and ran fine on small <15 min runs for a few weeks.

Yesterday, I tried going out of town, and it did the shift into neutral thing going after driving about 85 miles (no lights on). It wouldn't shift into gear. I was in the mountains and luckily coasted 2 miles in neutral into a gas station. I refilled on gas, since I was there. Started it back up, and it went into gear. I drove another 2 miles, and it shifted back to neutral and wouldn't go into drive. I pushed it out of the road, and got it towed home. Tow left it on the street, and I started it back up, put it in drive, and it pulled right up the driveway.

So now I've just got that it randomly shifts and sticks in neutral. There's no codes on the normal code reader. I don't have the special hybrid code reader.

 

My bad on being slow again. I've been reluctant to deal with this as it's car no. 2. Well, normally, no. 1.

I tried taking the battery to the dealer I bought it from and they refused to test it w/o having the car there. Said it's not possible. I don't really believe them, but that's what I got.

Other problem is, it no longer starts even by charging the 12V. I charged it all the way up to 12.5V, and tried starting it probably 10x times and got nothing. I think that means it's got to be more than the 12V, but at this point I'd have to get it towed again to the dealer. Any advice?

Also, @bisco, it's not the shifter. It won't even go into ready mode. So I'm a step short of trying to go into gear.

 

Yep. Both ACC and ON work. Steareo turns on, air blows strong, nav lights up, signals, and headlights all work. It's as @mr_guy_mann said, just no ready mode, and with that no power stearing, and no power brakes either.

I also double checked the voltage up from and got the same 12.5 volts, so I think the connection on the 12V is good.

 

Well guys, I decided to to try again to get it to the street to be towed and it started. Magical. Now it's on the street.

However, I'm a dummy. I have a bunch of the brake lights on before this started, and was planning to replace the skid ECU (89540-47130) after I fix this problem. Just clicked that I should replace the ECU I know is bad first, and see if that fixes both problems. I'll update in a couple weeks on the part ships and I get it on.

 

@abcsoup53

Updates as requested. First, for the brakes. It wasn't the skid ECU, it was the brake pump actuator, which I swapped (quite a job), and now all the brake lights are gone. Bonus: the brakes still work too.

For the intermittant start, it's still not fixed. Car's still sitting in the driveway. I had a newborn this year, and just don't have spare time to work on it.

I don't have a techstream. I did get it to start once and drove it to a prius specialty shop. They said it drove fine and gave it back.

They did send me a couple sheets of codes. Looks like C1241 or U0293 may be informative. Also got a couple gateway codes: B1260 and B1271, but they're listed as historical, not current. Could be a red herring. Or not?

If anyone has any new tips for me to check something, I will. I honestly don't know what to do with the car. It's more than I'm up for diagnosing personally, and the only hybrid shop in town outside of a dealer wasn't any help.