2001 Prius. 328000+ Milage Problem: Around 100* outside temperature(ONLY at high temps), The master alarm gets triggered. Gas and Electric motors stop working. Gauges fade to black, display screen goes to white. All electric power goes dead. A Jump start will bring it back to life and run fine. The 12v battery seems to be at very low charge. With a charge overnight the car will start and run fine... til the heat goes up. What would be causing the 12v battery to not fully charge while driving, but only when its hot outside... And its NOT a bad 12v battery, have had this problem on and off for 10 years and 240,000 miles... PLUS, 60,000 miles ago we had the gas engine, electric motor and inverter replaced. Any ideas?
I think it points to an inverter problem (the DC to DC converter is part of the inverter) Did you scan (or can you scan) for trouble code(s)?
Might the HV Battery be getting too hot? The battery cooling/exhaust fan and cabin AC working? Turbulence in the inverter cooling reservoir while running? Inverter coolant been changed? You need codes.
