P0A80 Code On 2009

welcome!

does your mechanic specialize in hybrids? does she have toyota techstream diagnostic software?

it could be the battery, or it could be the 12 volt, or it could be something else

 

Welcome. Besides what @bisco mentioned, it might be corrosion in the battery's wiring harness. Those negative voltages look to me like bogus readings from bad connections. BB12 looks low, too.

You'll want to make sure your mechanic is Prius competent.

 

that should give him the module voltages under load, and any that are outside parameters

 

Those 17 V numbers are for the traction battery. The 12V numbers you give here are for the Aux 12V battery. They are totally different batteries with totally different purposes, locations, chemistries, and voltages.

Not true at all. Even if the 12V gets down under 11V it should still power up. My brake pump was running for an unusually long time on my 2005 several years ago. It was the only symptom that my 12V was down to about 10 volts.

And the "13.89" when on isn't measuring the battery. It's measuring the output of the DC/DC converter that's charging the 12V battery.

It's true that a low 12V can throw codes due to insufficient voltage to the ECUs and sensors, but 12.5V in the morning is not unusual at all. If there's any doubt, put it on a charger overnight and read the codes again.

 

Since you have all the codes written down, just reset and clear the codes.

Then drive car around for a good drive. Go down hills if you can and lightly keep your foot on the brake.

Use the brake pedal more than gliding to a stop.

That should charge the hybrid battery back up and if it throws codes again check them and you may have to replace some cell modules.

Check ebay out, you can find them for like $25 each.

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