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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4432
Experience:  Toyota Master Tech, ASE Certified
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2005 Toyota Prius with 65,000 miles wouldn't start. Toyota

Customer Question

2005 Toyota Prius with 65,000 miles wouldn't start. Toyota dealer assessed need for new starter battery which was done. A few days later, drove the car on a 9 hour trip. Stopped after 4 hours. Car started up fine. A few hours
later, the panel lit up with engine light and emergency warning. Stopped car. Tried to start again. Won't start.
Car was towed to Toyota dealer which is closed today. (Several hours from our home dealership).
What are the likely problems?
Submitted: 2 years ago via
Category: Toyota
Expert:  Ted Ritter replied 2 years ago.

Hello, thanks for posting

It sounds like the 12 volt auxiliary battery is not getting charged back up, I'll explain briefly how this works.

The engine is not started by the 12 volt battery, there is no starter and no alternator, the 12 v battery is only used to power up the hybrid computers and power the accessories, lighting, radio and so on.

The battery is charged and kept at 12+ volts by the ac/dc inverter, since there is no alternator and no need for large amounts of current from this battery the charging current is very low (about 8-10amps) compared to conventional systems which charge at about 40 amps, it takes a lot longer to charge this battery back up and keep it at 12 volts or more. The engine is actually turned over from voltage supplied from the hybrid battery which turns the engine over through the motor/generator in the transmission. If the voltage from the 12 volt battery drops around 11.8 volts the hybrid system is not activated and this is why id doesn't start and the warning lights turn on.

It may be another problem, possibly a bad power button, fuel run out, smart key malfunction, the dealer is going to connect their computer and retrieve all codes in all computers and get stored data in freeze frame functions.

Pleas ask for an explanation for whatever they find and what they recommend doing and why, dealers are reluctant sometimes to give out diagnostic code numbers but they would help in case you have questions for me and want my assessment, ask for the diagnostic codes, even better ask for a printout of the data retrieved from the computers. Let's hope it's something simple. I 'm going to be offline for an appointment tomorrow but will be back in the afternoon.