4 Dashboard light always on

A scan tool was used that did not show you all of the trouble codes. We have a thread here that reviews a variety of code scanning apps and indicates which ones can read all of the codes from your Prius.

Gen2 OBD2 app review | PriusChat

Sort of by definition, "the machine is working at the moment correctly" is false if there are warning lights. If the system's self-diagnostics are able to alert you to problems before you would notice the problems yourself, that's what makes them useful. Sometimes a problem will be easier or less expensive to solve when it is caught early, before you actually notice that the machine will not get you where you are going.

As a convenience when you do not have a good scan tool at hand, the warning lights you mention are able to indicate the trouble codes by blinking patterns that you can count, if you apply a jumper wire between the Tc and CG terminals of the car's diagnostic port. A search of these forums can find many threads with more detail on doing that.

That method will also not show all possible trouble codes in the car—a good scan tool is needed for that—but the codes it reports will be a start.

 

My 2 Gen2 had this 3xact scenario and twas my brake actuator both times. 09 and 05 cars 05 in 2021. The 09 2022. The events happened 09 fixed . 05 not needed traction battery and host of other things parts car now almost stripped.

 

The thing is, that light combination could be more than a hundred possible faults, including ABS issues, so for you to have an ABS issue is not surprising. However, for it to be that fault every time is not a given.

As ChapmanF says in post #2, getting all the codes is the surest way to get to the root of the problem.

 

ABS 42 and VSC 45 both simply mean "hey, ((!)) has codes, have you looked there?".

ECB 41 is trouble code C1241, which pertains to weird supply voltage reaching the skid control ECU. That's not always because of a 12 volt battery problem; it can be anything in the wiring bringing the power to the ECU. But if the battery voltage hasn't been checked yet, a C1241 code makes a good excuse to check it. You should be able to find more about that code by searching for it.

ECB 65 is trouble code C1344, a complaint about controlling the hydraulic pressure to the rear left brake. There are about 8 pages for troubleshooting that in the repair manual.

There's at least some possibility that straightening out the supply voltage issue might resolve the C1344. Worth a try, anyway.

 

14v is the inverter power. measure with car off

 

There is a buzzer that sounds when certain trouble codes are logged, and indicates particularly dangerous situations.

Those aren't the only risky situations though. The system is already telling you about a problem with power reaching the brake ECU, and a problem controlling hydraulic pressure to one of the brakes.