Triangle Light on, brake system light, vsc light, car won't start.

welcome!
you would have to buy mini vci and a compatible laptop if you're going to diy. what were the results of your 12v test?

 

12.2 is a bit low, you may want to charge it and see if it holds.

 

...could be brake actuator problem which in USA has extended warranty
Brake Actuator Assem - Warranty Enhancement | PriusChat

 

You really need to retrieve the DTC's with a compatible scan tool or mini vci cable and computer. The mini vci cable is about $30.00 on fleabay or amazon. Genertic OBD II readers are generally not capable of retrieving the Pri's DTCs. If the indicator lights are lit that you mentioned you have stored DTC somewhere.

Out of curiosity you replace the HV battery and the 12 volt battery 4 months ago.? What were the replacement batteries? New, remanned/rebuilt/used.? What triggered the need to replace the batteries four months ago?

 

With respect, I can't even make sense of saying "this issue" before the thread has mentioned the diagnostic codes, or even which warning lights were on. There's no way yet to even know whether the issue in your car is anything like the issue you are reading about in someone else's post ... other than that they're both issues that make warning lights come on, which is pretty much all of them.

Just identifying what lights are on would be helpful in this thread (even though even that, by itself, is still not enough to start saying "this issue"). It can at least suggest which of the car's computers are reporting an issue, and that can be helpful to know, because some of those computers (but not all of them) are capable of blinking out their diagnostic codes for you if you do not have a suitable code reader.

-Chap

 

Sorry, I missed that the lights were identified in the thread title. Anyway, while that's still not enough to pin down an issue, it's good news, because the brake and VSC codes can be read with a jumper wire and counting blinks.

-Chap

 

Hold the bus for a moment. Why do we always think we need codes before we can do anything? I'm just getting to know these cars myself but I've had a couple experiences that might shed some light. If you have the brake actuator issue wjtracy mentioned you will probably notice that the actuator, which is an electric pump will run for a while, stop for a short period or not at all then run again (short cycling) just like a water well with a bad pressure tank, and for the same reason. If you stick your head under the rear bumper you will likely hear a hissing sound when the actuator stops. This is an internal leak in the pressure accumulator which is part of the extended warranty. I'm fairly certain the extension was for ten years after the new sale but check with your dealer to be certain because it is about a $2400 dealer fix but I was told by the tech you can do it yourself without special software. The other issue I had was corroded copper connector link bars in the hybrid pack. I just removed them, soaked them in muriatic acid for a short while, then in baking soda water to neutralize, then a water rinse, then wire wheel and they are like new. I then cleared the codes and all is well. I hope yours is as cheap and easy.

 

You will also need an OBD software that can read ABS codes and possibly more. I bought the LAUNCH C-Reader for about $100 from Amazon and it worked fine.

 

You can also read the Prius ABS codes with a short length of wire by counting light blinks; this can be handy if the warning lights come on when you don't have your $100 reader with you.

In general, I encourage people to read the codes before assuming they know where the trouble is, just because there are a lot more possibilities than most people assume. People often post as if they think they are guessing between 2 or 3 possibilities, not 20 or 30, let alone 200.

You've given a good example of what would be clear evidence of a brake accumulator internal leak (the continual pump running, I mean; I'm a little less sure about hissing behind the rear bumper, as the acculumator is in front) and if someone were to post about noticing the pump running a lot, that would be a good early call. You could construct similar specific ways to test for a lot of other specific problems. If you had a car that lacked the ability to give you codes, that is what you would have to do, and just run through your list of specific checks of possibilities, with a variety of tools and instruments and amounts of labor to do it.

When your car can give you codes, though, you've got a muuuuch faster way to know where to start.

-Chap

 

Because it points to the most likely area of where the problem is.

You can diagnose 2 problems without reading the codes (or can you?) because you have experience and other added input from experts, but that skill-set is typically not the type of people that come here seeking help.

The DTC trouble indicator lights can mean so many things, it is most helpful to read the code to eliminate what it isn't and focus on what it might be.