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.

 

Thanks RJ,
I have checked my original fuel pump out of the car and it works. I did replace it with a new Delphi pump. I replaced my crankshaft sensor with one from Denso which has a chip inside that makes it 10 times more sensitive. I'm going to have to use my old analog meter to check for a short between the crankshaft sensor connector and two specific terminals in the ECM connector. My meter wires allow about a 4 foot reach, so hopefully that's enough. This fault happened suddenly about a year ago. I've had it diagnosed by Toyota, but that proved as futile as a confrontation with the BORG! The shop manager told me directly that he would have to put my car through a number of expensive tests(like pulling my fuel tank, removing and cleaning my intake parts, and numerous other things) before simply doing a test of the wiring as I made a request for! Sometimes depending on a dealer to find a cause(as in my case) is not a cheap option. Toyota failed to even recognize that the P0335 code was there(because they replaced my 12v and then ran a diagnostic that did not show the code) I simply went to the place, tried to start the car, got the codes on my Dr Prius app, and the shop manager treated me like I did not know what I was talking about. They were all over me about needing to replace my hybrid battery, and that was after I even told them I already had one to put in myself(which I did and that did not solve the non start problem either) I put in a new LiP04 and have been keeping it charged with my device I used to keep my old NiMH battery going as it was failing. I also have been keeping my 12v charged up with an old 2amp trickle charger. If I have to replace the wiring and connector for the crankshaft sensor then I can easily get the part from Rockauto. However, the process in steps to remove and replace that wiring is something I'm going to have to read up on somewhere because it does not look simple! RJ if you have any suggestions on where to read about that it would help! I see in the link to the repair manual that I got from Chapman that I need to check the rotor that the crankshaft sensor reads, but don't know an easy way to do that. If this turns out to be a fault in my ECM then getting a used one might be an option, but I'm hoping I don't have to do that. My best local part yard did not have one, and no engine parts either because those sell fast. Worst case possible iff an engine is needed....a place in NJ listed on ebay has whole engines with all intake and exhaust parts included with about 50,000 miles on them for free shipping and a reasonable cost! I don't want to have to go that way either!!!!!

 

Based on your earlier posts you 95% need an engine or major engine repair due to a blown head gasket when it did run. However it is very likely you now have some kind of engine no start problem, most of which have no codes like hoses or connectors poorly connected. The aftermarket hv battery is suspect as well.

You found a link where other factors besides the position sensor can cause the code you referenced on another thread. Very likely since you have changed the part, maybe a couple of times.

Then the lithium battery and having to ship it back to update the questionable hv battery voltage sensor interface. I believe that interface has changed again.

Changing the ecm is questionable as well especially if it is still online.

I would find a local hybrid independent and beg for mercy. Bring all the original parts that are available.

 

None of that is likely. My new battery is functioning well. I've not had any problems with my engine since I had the head gasket replacement years ago. This non start problem coincided with the HV battery and 12v battery failures, but has persisted even though both the 12v and the HV battery are new, charged well, and there is only a residual P0A80 code that eventually will go away. The current engine codes are simply the P0335 and two general ones that show a non working engine. Lots of posts come from high mileage gen 3 owners about the P0335 code with a non start problem. In my case heat and maybe light oil spray contamination to the wiring may have caused a short. I will just have to track it down by testing the resistence between the connector and two related points in the ECM connector. Any step-by-step instructions on removing and replacing the harness would help! I'm using the link to the manual from Chapman.