2009 Prius, started eating through 12 battery charge about a month ago. I measured around 1.065 amps of draw on the 12 volt battery after sitting for around ten minutes after a solid drive today. The battery had been charged up, disconnected, and left alone for around a week prior to today's travels, and the battery held that charge just fine (so I'm not thinking bad battery yet). While the car if off and sitting, I pull and replace fuses in the engine compartment until I hit one that instigates a substantial drop in current, down to around 100 mA (I feel like that is still a touch high, but, baby steps..). That fuse is labeled "DOME" and I've seen reference to it so I think to myself "awesome, we can live without the dome light, case closed!" Button the car up, test for power - nothing. No dash, no wake up, no functional car. I replace the 15 amp "dome" fuse, car starts up just fine. This car is also recently experiencing a display issue in which the MFD mostly just shows white with some vertical lines (but the touch functions still work if you manage to hit the correct spot) in case this might be related. Ideas?
First, how are you measuring the current? If the hatch is open that alone will cause hundreds of mA of draw. One way to prevent that is to stuff a carabiner of about the same size as the hatch latch loop into the slot until it clicks. Just don't forget to remove it (press the "open" button on the hatch) before closing the hatch. Second, you want to wait a long time before measuring this. Letting it sit overnight and with no key fob anywhere near it would be ideal. Even hours after being turned off the car can spin things up, and if you happen to be measuring then it will change the measurement. Lots of possibilities, some "common" ones: Type of failure in the combination meter. As I understand it, there is a circuit that causes it to draw power for a while after the car turns off. If that circuit fails the combination meter will continue to draw power indefinitely. JBL amp under the right seat can do this. Tracking device from used car dealer attached to ODB2 port. These are tucked up into the dash and the owner generally has no idea that it is present until they try to track down a parasitic load. Failed door/hatch sensor. Any aftermarket device wired onto the car. Note: if memory serves both the combination meter and the ODB2 port are on the Dome fuse.
