Warning lights turned on as a group and turned off.

How old is the 12 V battery? A marginal, 12 V battery could cause a large number of problems. Another hypothesis is a loose or marginal connector.

What was the weather like when it happened?

The easiest suggestion is take to a dealer and ask them to read out the codes. Bring them here and we can look them up.

Bob WIlson

 

Good deal.

That is an excellent place to test. If you can, check the terminals for any evidence of corrosion too. The red-cover over the B+ lifts up. The 12 VDC system powers the control computers and there is history of strange symptoms when or if it goes weak.

The main thing is a loss of power but there is a master and HV battery warning light. Check the owner's manual but the master light looks like a triangle with an explanation mark in the middle. The battery light looks like a battery with the word "MAIN" under it. Usually, turning on the ignition but not starting the car will show all warning lights.

Just a guess. <GRINS>

Bob Wilson

 

Hi there,
Bob is absolutely right. When the 12V battery gets old, Prius behaves wacky! I had lights randomly go on and off, plus my radio would make "squeel" and "screech" sounds when I started it up in the morning. When I replaced it with the Exide Sprial Cell battery (it does not ever vent, as it has a recycling feature that recycles any gases back into the battery), and my car has been awesome ever since. I would suggest it versus the Optima as it is cheaper, longer warranty, and a significantly higher capacity in terms of Watt hours. Its been in there for 2 years, and still reading perfectly. Even in -20C temps here in Ontario, Canada, it still would show up with 11.9V of power in the morning. My Toyota Panasonic often read in the mid to low 10V territory in similar weather.

 

Also, are you sure the lights were really lit. What you describe can appear to happen when external lighting hits at just the right angle. As the light sweeps, the indicators appear to come on one after the other.

Tom

 

With the car running, you are seeing the normal 12 DC charging voltage, ~13.95 V., and not the traction battery. But even a static test of the 12 V battery is not as good as a 'load test.'

I believe many of the auto stores like Autozone and tire places will do a battery 'load test' for free. Of course they want you to buy a replacement battery from them but ...

We also learned that Sears now carries a Prius compatible, 12 VDC battery. I don't know the price but I suspect it is competitive.

It sounds so much like something 'reset' and recovered but I'd never seen anything like this described before. Just that we know a weak, 12 VDC supply can lead to many 'unusual' symptoms. Sad to say, reading the charging voltage of a running Prius is not the best approach for testing the battery.

BTW, if the 12 VDC battery is taken out, it will wipe out any stored codes. The easiest source for reading the codes would be a Toyota service center ... who can also test the 12 VDC battery at the same time. ... Again, they would like to sell you their battery.

GOOD LUCK!
Bob Wilson

 

Typically, you'll be charged for one hour of labor time, maybe $100 or so.

Assuming that your battery is 8 years old, a better use of the $100 would be to apply those funds towards buying a new battery. If you don't have any warning lights on, it's questionable that any DTC will be logged.

 

Or you could try my approach:

"Honey, I read how to fix it in Prius Chat. Come on out, I need your help." ... grab a rubber mallet.

Open up the car in front of the girl friend and shout,

"In the name of Jesus, Demon be GONE!" and whack the air inlet cover with the mallet.

"Ok Baby. I won't happen again. The guys at Prius Chat assured me this is what Oral Roberts Toyota Service Center in Tulsa Oklahoma do."

Bob Wilson

 

This statement is misleading. "Normal" charging voltage has a range, which is dependent on temperature as well as the 12V battery's state of charge. 13.95V is within that range.

Another statement, also posted today, reads

Also not necessarily true.

The Prius 12V batteries are not SLA batteries and do not have cold cranking amps ratings. Without that rating, a load test is meaningless.

See above.

True, but the event occurred while the vehicle was on the interstate. The vehicle's DC-DC converter—not the 12V battery—would be supplying the vehicle with auxiliary power at that time.

Actually, it's not a test of the battery at all. "Charging voltage" refers to the output of the device that is charging the battery, not the battery itself.

That is not always true.

It's a well-designed unit. Install it and forget about it.

Good luck, indeed.

 

Just a point of correction: Prius do not have alternators.

Tom

 

Certainly an interesting symptom. I don't remember seeing it reported before. One thing about intermittent problems, they tend to come back.

Bob Wilson

 

Prius have two motor-generators (MGs). They are used as motors and generators. In that respect you could consider them as two BIG alternators, but they aren't alternators in the normal sense, hanging on the engine and being driven by a belt.

Tom