2013 Prius C III ECU-B No. 2 Fuse Blew

Hi All,

I had an unfortunate incident Friday evening when trying to leave work. Car ran perfectly fine in the morning, and everything worked as usual. Weather was mild with light rain, although roads and car were wet in the morning from heavier rain the night before.

I returned to my car in its parking spot in the evening, but was unable to enter normally (automatic door unlock didn't work). Thought maybe the key battery had died (although didn't get any warning of that). Used the manual key to enter the car, but could not start the car no matter what I did (pushed key button with remote against the button multiple times, while holding down the brake pedal, etc.). After about 30 mins, gave up and got a ride home.

I returned the next morning with a multi meter, fresh batteries in both key fobs, and other tools. Started testing the fuses one by one, and found the 7.5A ECU-B No. 2 fuse in the engine compartment had blown. Luckily I had a spare 7.5A fuse and replaced it, and everything came back online.

Unrelated to this (I think) a few weeks prior both of my tail lights went out at once (so likely not bulb failure), although brake lights, turn signals, etc. were working fine.

Any ideas what would cause this? My only suspect is perhaps something in the circuit got shorted by some water leaking in somehow, but no obvious leaks or water intrusion noted. I'm carrying a box of spare fuses with my in my glove compartment now, but worry if there is an underlying issue.

Any chance I need to replace my ECU-B? Where is it located on this car?

Thanks!