Red Triangle, VSC, Chekc engine, brake - all lit up

welcome!

how many miles on her?

 

The error codes and especially the subcodes are what you need to retrieve to diagnose... Dr. Prius app is easy to use. And here's buyer guide for device that reads the error codes: Hybrid battery diagnostic and repair tool for Toyota and Lexus

 

Sounds like something went wrong with your battery check... You should be closer to 12v than 19.9v... I think your volt meter is messed up.

 

Yeah... That's a dead 12v battery problem for sure... You can try recharging, but most likely will have to replace.

 

Where/how did you do the "battery check"?

The vehicle signal check screen on the MFD reads low on all the cars I've checked (it is probably an accurate reading of the volts arriving at the MFD, low enough that if I happened to see 11.9 there I wouldn't give it a second thought. It won't stop you reading the trouble codes if you have a way of doing that. (For brake system codes, you always have a way of doing that, because they have a blink-out-on-the-dash feature you can trigger.)

 

To be clear, do this 12v battery check and let us know results:

 

12v sounds okay, time for codes

who installed the hybrid battery, is there a warranty?

 

Do you see the icon of a car in the upper left corner of the mfd the screen above the radio. If so the hybrid battery has failed.

very very common on this site G2 hybrid batterys failing left and right. High mileage car driven daily all of sudden you hardly drive it at all battery doesn't get charged. Its death for the hybrid battery and usually the 12 volt too. The car is so complicated even a bad 12 volt battery is a head scratcher. Most cars you hear the engine turn over slow yep its the 12 volt. Not on a prius.

I'm afraid your hybrid battery failed its the #1 post on this site. Based on the 11.9 the 12 volt is looking for the exit door too.

 

,it’s not just charging behavior lots of times there may be a micro cracked leaking battery module in the battery case it makes a mess of corrosion and starts to conduct and throws a grounded fault. See that often.

You know if it’s a ground fault if you can disconnect the 12 volt battery wait a bit then reconnect it that will clear the codes and allowyou to drive some more till it launches the RTOD again.

Letting it sit will also excite corrosion on an old battery.

 

Was the engine oil dipstick indicating closer to low mark or high? There has been a known issue that with engine oil closer to the Low mark, marking turns can cause oil starvation to the engine and it can throw all the brake codes up.

 

The 12 V battery is fine. Move on, nothing to see here.

 

yeah dolj Having owned my car 13 years and on my 3rd 12 volt battery what would I know about it?

11.9 is not good on a Prius. healthy prius battery lives at 12.6.
if you had a battery re conditioner I would use that.

Yes you can disconnect it at work. 2 different ways one is unbolt the ground lead off the car chassis not recommended as there will be sparks the other is pry off the red plastic battery cover and there is 2 black leads plugged in that black plastic assy on top of the battery. The
big fat lead is the main B+ lead that's bolted to the front jump point under the hood. Those 2 lead plugs juts unclick by depressing there little levers and gently pulling out. Wait a minute then gently re-insert. Then re-insert they will click.
The red stuff all over everything is 100% synthetic grease to prevent corrosion. Works great.
The extra red lead on the 12 volt terminal is for a towing light aux power supply.

Sometimes after you restart the car it will show alot of codes that's ok just shut the car off and start again there will be no codes. The cars system freaks out when the 12 is disconnected.

This 12 volt reboot will clear all the codes the car has launched. if you can drive ok after that you may have a ground fault issue with the hybrid which is very very common. It will re-launch the code again though after a while somtimes fast sometimes takes days.