Prius 12v suddenly cut off

My 2004 Prius suddenly lost 12v electric power yesterday. Before it happened the car has no issue. It happened when I just got home and turned off the engine. I was going to lock the car with remote, and I saw no lights on the dashboard. I started the car engine again, but nothing happened. Something seems to be wrong with the 12v power supply.

The car was running fine before it happened. What I did before the problem started was changing the air filter inside the car. At that time, Chip Monk was building a nest and removed all the leaves that were in it. Just replaced with a new filter.
There were a lot of electronic circuits around the blower system, but I haven't touched it in a year.
The blower was working fine before and after removing the dust.

Today was the hottest day of the year, 90F. I've never had a problem driving at 90F or over 90F.

Could it be that the problem was caused by touching the wiring of the surrounding electronic equipment while removing the dust inside the blower and causing a poor connection?

I have removed the wiper motor to clean the blower, but will it cause any problems?

After that, when I went to start the engine once, the 12v power supply was working naturally, and it was possible to start the engine.

However, after I stopped the engine, the 12v power supply was lost.
I measured the battery voltage and it was 12.7V. The battery is a genuine Toyota battery that was replaced three years ago.

I thought that maybe there was a poor contact somewhere. Could this be caused by bad wiring connections?

Please let the opinion of everyone. thank you.

 

Hi Mendel and Sam,
That makes sense. But, it is still really strange because today I checked the Prius and found the power was backed! I left the car over night and didn't touch anything on it at all! I checked the voltage of the 12v battery again and it was 12.3v. The battery's voltage was slightly lower and I think it happened because I kept opening the hatchback door so the interior light was on when the 12v power somehow came back.

I tested drove the Prius and it runs well until I finished test driving in my neighborhood and turned off engine. The 12v power was lost again which was just like before! I It is very strange and I am wondering what could cause it?

I checked the voltage on the battery when it was still connected to the vehicle. Right now I disconnected the battery from the vehicle and am charging it. When I disconnected the grand wire from the vehicle's body, I thought the bolt was fixed tightly. I will make sure the connection when I connect the battery to the vehicle again.

I think both of you and Mendel are right! Most probably it could be some connection issue. Or, it cold be short circuit issue somewhere...
I am suspecting a problem with the car's blower motor or resister module because this problem has started after I cleaned the air filter.

Another possible cause is the connection of the blower for the hybrid battery. More than two months ago, I cleaned the blower of the hybrid battery. At that time, I remember that the electrode of the power socket of the blower was partially rusted. Is the Prius computer designed to shut down the system if the hybrid's battery blower power connection is bad? Just my speculation, though.

I was worried about it too. I will check the voltage as you suggested!

 

I disconnected the 12v battery and charged it over night and reconnected it. Securely attached the negative electrode wire when connecting the battery to the car chassis. The 12v power supply is good. This time I did ODB2 before test drive and there was no errors. Testing the vehicle was good too. However, the problem is that the power sudden lose, so I'm going to see how the car is for a while. Thank you very much Mendel and bisco.

P.S.
FYI
While researching the cause of the problem, I found some other possible issues for my Prius 2004.
1) collusion of hybrid battery fun's power supply connector's pins.
2) hybrid battery inverter coolant water pump recall

I lately replaced all four suspensions of the vehicle and found that the hybrid battery fun's power supply connector pins were corroded. I cleaned the corrosion but didn't replace the pins. The issue causes hybrid battery system error. I think I should replace the pins or the entire connector.

I checked if my Prius is one of the recalled vehicle but could not find any recall for my Prius. This issue causes sudden loss of 12v power while driving the vehicle. I am 2nd owner of the vehicle so I am going to call Toyota for double check for the recall.

If you know any other issues or any maintenance you recommend for 2004 Prius, please let me know.

 

I've looked at the air intake and cabin blower construction and haven't found anything that might cause a problem. Some people put net on the intake. I am thinking about doing it too.

 

I may have misled you. The connector I mentioned is the one used for hybrid battery cooling fan power supply, so I probably don't need to replace the parts you suggested.