P0A08 error code

A 12-volt battery is needed to start the hybrid system.
After the sign “ready” lights up on the display, the hybrid converter supplies the car’s network with a voltage of 13-14 volts, which is used by the car’s systems and charges the 12-volt battery.
Is the "ready" light on on your car?

 

Another bit of info. I Googled how to check the charging system, and came across a whole series of YouTube videos created by Professor John Kelly with the Weber Auto YouTube Channel, part of the Weber University. This one in particular is very helpful and answered several of my questions.

The demonstration is using a 3rd generation Prius (2017), but the tests described would be similar for a 2nd generation (2004 to 2009).

I don't yet have a multimeter capable of checking DC amps, but I will investigate getting (or borrowing) one of those.

From the test just for battery voltage, I am definitely not getting any current to the 12V battery. Connecting my multimeter to the jump start contact under the hood and to ground, the meter reads about 12.5 volts whether the car is "OFF" or is "ON" and "READY".

Now I need to check the DC Amps entering or leaving the 12V battery to determine if the DC to DC Converter is working properly.

The only other possible cause I can think of would be if the fusible link block at the positive terminal of the 12V battery is blown. Checking the amps going to the fusible link block and then between the fusible link block and the battery positive terminal may be the test to determine what is wrong.

 

Thanks for your reply, which i just saw after posting another update. Yes, the "Ready" light comes on.

 

After turning on the "ready", check the output voltage from the converter white wire connector (B) pin 1.(AMD)
If there is a voltage of 13-14 volts on the converter, the wire to the fuse and relay box may fall off.

Converter by MAX2 posted Aug 21, 2024 at 8:33 AM

 

Thanks for the additional option in diagnosing the output of the DC to DC Converter. Am I correct that this connector (single contact grey connector) is buried deep in the engine compartment, near the left and near the bottom of the inverter/converter? Or is it someplace more easily accessed (and without having to remove the inverter/converter?) Perhaps at the other end of this wire at Unit A of the main fuse box under the hood? I've seen videos of how to replace the various fuse box units ... but if it is pulled out to access the side terminal where the wire connects, would car still be able to be in "Ready" position? I haven't tried to look from below to see if the grey connector from the converter is reachable ... would you happen to know?