The other day my Prius started doing this: (I apparently don't have enough posts to paste a clickable link) I usually keep my foot on the brake to start and stop the car. In the video you can see that when I press power, the car still seems to be on, but with flashing lights. This stops when the door is opened, but then reappear when the door is closed again. They usually eventually stop flashing after the door is open, but the passenger airbag light remains lit. I can only lock the car with the actual key as the fob doesn't work when this happens. When I press the power lock on the inside of the car, the car immediately unlocks all the doors again. Anyone have any clue what's happening here?
I didn't notice the green light illuminated on the Power button when you pressed it. If your foot was on the brake and the 12V is okay, I'd suspect the brake switch behind the pedal. Without the green light, when you press the Power button the car goes into On or Accessory mode (I forget which one first), with no Ready light on the dash. Why the PRNDB lights were blinking, I don't know, maybe Gen II reacts differently.
I suspected it was the battery and so I replaced it. It seemed to work yesterday afternoon, but this morning the problem is back. I can drive the car just fine. It's just getting out and locking it is a pain since I have to use the key and all the lights in the dash.
I should add that when the car is locked manually with the key, the passenger airbag light remains lit, as well as the no key icon on the dash.
Just to make sure of the brake pedal switch, do the rear brake lights come on when you step on the brake pedal? It's a head scratcher...
This means that at least some of the car's electronics remain on, which will lead to discharging the 12V battery. You need to have your car taken to your local Toyota dealer to figure out why the power remains on. Most likely, the IG1 relay is stuck in the closed position. If you want to figure this out yourself, obtain the electrical wiring diagram at techinfo.toyota.com and find the relay which provides power to the SRS ECU. IG1 is that relay and is located at the relay/fuse box under the dashboard, driver's side.
Don’t let the 12V battery run empty. Your car is using it as Patrick Wong said above. Get the problem fixed before 12V gets empty. 12V battery getting empty will leave you stranded and it may ruin the 12v battery that isn’t cheap.
