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post #1 of 2 (permalink) Old 06-03-2017, 12:50 PM Thread Starter
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Default 2001 gen 1 prius: Apparently the 12v generator quits after a few minutes

I have 2001 Prius. I have a voltmeter on the panel, and when the car is off, it shows 12.1 or so. During start start it goes down to 11 or so, and when the engine starts it goes up to 13.6. So far everything is normal. But after a few minutes, the voltage goes down to 11.5, and then it keep going down. At 10.5, the square around the D for Drive disapppears, and the car won't move. Then the screen starts to flash, and everything dies. But after 15 minutes I could start the car again and the cycle starts over.

The warning triangle is lit, and there is a message on the screen with three icons, PS, main battery and car with triangle. Last one is marked. I can't see any codes.

The car is at a non toyota shop, and the guy there thinks it might be the alternator.

Any ideas? Also, I thought that the 12v system was fed from the high voltage system, at least when the combustion engine is nut running.

I posted this at priuschat.com as well.
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post #2 of 2 (permalink) Old 06-05-2017, 12:41 PM
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Your car does not have an alternator. Take it to a different shop.

You are correct in your understanding. When the Prius is on ("Ready" appears on dash), the 12V auxiliary battery is maintained by a DC-to-DC convertor that steps down the 273V main battery voltage to about 13.8V to keep the 12V happy. It has a maximum current of about 80A. I'm not an expert, but I have some better ideas than a non-existent alternator:
- I think there's a charging fuse in the red plastic block attached to the 12V auxiliary battery. Check to see if it is OK.
- Maybe something in your auxiliary electrical system (e.g. after-market GPS, stereo, etc?) is dying and drawing way too much current, overloading the DC-to-DC convertor and shutting it down?
- Maybe your DC-to-DC convertor is dying and needs to be replaced?

Douglas (2002 Prius, 2006 Highlander Hybrid, Wisconsin)
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