Electrical problem out of nowhere?

Buy one of these devices: Panlong Bluetooth OBD2 OBDII Car Diagnostic Scanner Code Reader Check Engine ... | eBay so you can connect your phone to the car so you can use an auto diagnostic app like Dr. Prius app to read and clear the error codes. In the meantime, if you want to see if your car can work again while you wait for device to arrive, you can disconnect the 12v battery which will reboot the system and car will forget the error codes till it finds them again.

 

In some cases a low 12v battery can cause a no start. The best approach is to remove the 12v battery and take it to an auto supply for a load test. Be extremely careful about jump starting. A reversed polarity jump can cause major damage.

If the battery is ok, the smart thing to do is to have it towed to a dealer for a diagnostic. For an hour's labor rate they will tell you exactly what is wrong. A few faults like a failed inverter may be covered free by Toyota even though the car is long out of warranty. Other issues might be quickly resolved. The remaining high dollar issues, if diagnosed, deserve getting quotes from independent hybrid mechanics.

 

a low 12v can wreak havoc with the computers. best to start with confirming good or bad, not guessing.

most of the low volt stuff runs off the 12v, replenishes by the hybrid battery, replenished by the engine.

the a/c runs off of the hybrid battery.

if the 12v is confirmed good, you'll need trouble codes. most problems don't come out of nowhere, although they may seem to. they generally deteriorate until critical mass is reached.

 

the high pitch whine and warning lights may indicate the common 3rd gen brake actuator failure.

 

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The brake alarm sound comes from a piezo speaker that is under the dash to make the sound on purpose, and sounds like a very steady high-pitched deliberate beeeeep.

Usually, when I read someone describing an electrical "whine", I imagine they are talking about something else. But sure, if there is a steady high-pitched beep coming from a piezo speaker under the dash, then yes, it could be the brake alarm.

 

5 minutes is not nearly long enough to charge the 12v battery, especially one that was discharged enough not to start. As indicated earlier, take the battery for load checking. They or you will have to charge it first. Overall it is a good sign that it started and ran.

 

Hey RJ,
Good point because the slight return and quick loss of power again is due to that 12v battery. I had this happen also. In my case the battery was also at the end of it's life and needed to be updated to the agm type required by the gen 3 Prius. Fortunately for me this was found by Toyota because I was clueless about the battery in place only being a one or two year battery and not even the right type! The dealer put it in when the head gasket repair was done.
I know this is a two year old thread, but RJ do you know how often these electrical problems are also related to failures within the casette type relay devices plugged in the fuse box? I saw a note about this possibility, checked the health of one obvious relay, and determined that the two cassette type ones control some critical parts. Checking the health of the microelectronics in the one that has the 1B plug that controls the fuel pump would likely require a link to my pc!!!!
So, even with a new 6 year agm Toyota 12v and a new hybrid battery....I still have a non start condition. Waiting on replacement of the two casette relay parts.....

 

Overall it’s best to continue your questions on the last thread or better yet create your own thread and start with all known details of the problem (no start) and what you have done so far.

Those two “integration” relay modules are rarely bad. They are simply fuse and relay modules which are sealed to protect the relays. But they are relatively cheap on eBay so push come to shove…

In your case, with a question about fuel pump operation, I would verify fuses then check for power and ground directly at the fuel pump. No power there? I might verify the pump and it’s ground with a power probe or a straight 12v jump.

We don’t know the basics of your situation such as does Ready comes up, dash lights or codes. It is very possible the old fuel pump is still good and the no start problem is elsewhere.