Water intrusion caused corrosion of the main engine wiring harness which caused a fault in the auxiliary 12v battery and has made the vehicle undriveable. toyota cannot determine the source or cause of the water intrusion even though i have brought in the vehicle for routine maintenance since i purchased it and i have complained about a problem which is related to the auxiliary 12v battery several times in the past. this seems to be a flaw in the 2004 prius design. *tr