2012 Prius Five- Had an annoying vibration coming from the trunk area at highway speeds- especially on concrete roadways. First thought was the problematic rear license plate/frame that I’ve read about- so I used some felt pads around the rear plate & frame but still had the annoying vibration ad highway speeds. Over the weekend I had some spare time so I started poking around in the trunk area by rapping in several areas with a heavy hand till I heard the same (or similar frequency) vibrating sound. Eventually I was able to isolate it to somewhere under the rear deck. I removed the carpet, then plastic deck then even the spare, etc… Found it was actually coming from the sheet metal box that surrounds the connections coming from the car and relays to the hybrid battery box. Seems the metal edges of that small connections/relay enclosure were just touching the battery box metal enclosure just lightly enough to vibrate under certain conditions. But how to fix? To make a long story short- I disconnected the 12v battery, removed the black exhaust duct over small metal cover, removed the battery cooling fan intake shroud, then two annoying orange lock rivets, then a few 10mm nuts and one 10mm bolt- and finally the metal connection/relay cover came off. Once off- I used black electric tape to line every seam where that metal cover touched the battery box metal cover or car frame- I then lined the battery box metal cover the same way in the areas where the connection/relay cover mated on it. Reassembly was the reverse of disassembly. Upon ride to work this morning- vibration was 100% gone- fixed! If you’re hearing some vibrations coming from the trunk area- remove the deck cover and rap the area over the hybrid battery box- that should indicate if you’re having the same issue as I had. EXERCISE EXTREME CAUTION WORKING WITH THE BATTERY, RELAY BOX, CONNECTIONS, ETC.. IN THE REAR OF THE PRIUS- THE HIGH VOLTAGE CAN KILL YOU! IF YOU HAVE ANY RESERVATIONS ABOUT WORKING AROUND THE HIGH VOLTAGE BATTERY PACK- SHOW YOUR TOYOTA DEALER WHAT YOU FOUND- AND LET HIM FIX IT FOR YOU!
Good solve! I had a similar noise in that area last summer but solved it a different way. Your method is better. I could not figure out how to get the carpeted cover plate off of the HV battery pack.
It's a two piece set- Passenger side has a 10mm bolt that threads into the metal relay/connector cover box plus two std panel plugs (the type used in door panels) the driver side cover just uses a few panel plugs. A 10mm socket wrench and a good tug and they're off
