Gen 2 Power Faliure

[T3Dan]

I've had an issue with my Gen 2 Prius T3 which has given some cause for concern. Probably going to get it looked at, but thought it might be worth getting some advice so i have an idea of what's coming.

Got home yesterday and shut the car off, only to find that the key fob wouldn't lock the car - subsequently found that the car was completely dead, no interior lights, wouldn't start at all. Tried jumping the car from the lugs in the fuse box without success.

Eventually found some advice online and disconnected the 12v Battery earth for a few minutes, reconnected it and got the car started. However, there was no indication of what caused this failure or why. I took the car on a long drive yesterday PM and it's been fine since though I've noticed that the traction Battery charge seems to be holding at a higher level than before and the charge seems to be made up faster - I did a few laps of a car park in EV mode this morning to run the Battery down. and it was back in the green after about 20 minutes of driving going home.

- Last service was January 2020 @ Toyota - they did a hybrid health check with was all fine

- Car has104k miles, but has only had light use since March due to covid - generally local journeys.

- 12v battery was replaced about 18 months ago

I've read a suggestion that this sort of failure could be a sign of a HV leak - possibly expensive if it's an issue with the battery on the inverter.

Any suggestions from those who might have experienced his issue would be appreciated!

[Joseph D]

17 hours ago, T3Dan said:

disconnected the 12v battery earth for a few minutes, reconnected it   ...   though I've noticed that the traction battery charge seems to be holding at a higher level than before and the charge seems to be made up faster

This is an effect of disconnecting the 12 V Battery.  It will settle back to more like normal after the Battery ECU has had a chance to recalibrate itself.

I would suspect your actual problem is related to the 12 V Battery connections.  You removed and reconnected one, just check the positive terminal and the connection of the negative to the body.  Make sure all are clean and tight.

I doubt it is a HV battery ground isolation fault as with this it will not go all dark like you mentioned yours did.  It just will not go into READY, but will light up the dash and allow moving to N or P.