2008 Prius not starting! HELP

Do the brake lights come on when you press the brake pedal? This should work in all modes including OFF.

If not, the brake light switch has stopped working and the car can't tell that you're holding down the brake pedal when you press the power button. Check the 7.5A fuse marked STOP is intact.

If the brake lights don't come on until you've pressed the pedal quite a long way, the switch needs to be repositioned so it comes on as soon as the pedal is pressed.

If the brake lights do come on, but the car won't go READY, check the wiring from the brake light switch to the Hybrid Vehicle Control ECU (HV ECU) and to the Power Source Control ECU. This wiring is part of the main Instrument Panel Wire harness.

Since it will shift out of Park, it's quite likely that the connection to the HV ECU is working properly, but the connection to the Power Source Control ECU isn't. This connection is made between a junction connector J9, in the extreme left of the dashboard, and the wiring harness connector IA3 which is at the top of the extreme left of the dashboard.

If you find that any of these connectors or wires are damaged I would ask for the wiring to be thoroughly checked over before driving the car.

 

Did you disconnect the HV battery before you carried the work out?

If so, you're sure you clicked it back properly?

 

I would put my money on the 12V battery being weak.

 

Taking one step back: why was it necessary to replace the airbag? Was the car in a collision?

 

My idea is that the SRS ECU thinks there is still something wrong with the airbag system, so you should take the car to a Toyota dealer to have the DTC read. Good luck.