Just bought a used Prius. It has about 175,000 miles on it. All seems to work fine. First Prius. A noise occurs when driving - sometimes idling - from rear inside car. Removed all stuff from the rear area including spare tire. There are cables on passenger side leading into an area where the noise is coming from. What is the possible problem? What can I check besides taking it to Toyota dealer (many miles away)? I haven't looked under the metal shield. I work on cars as a hobby, so I am not afraid to check things out.