Highlander Hybrid Humming Noise at Highway Speed

[lartsai]

Just bought a 2013 Highlander Hybrid a week ago. I have noticed a faint, intermittent humming or buzzing sound, particularly at highway speed that comes and goes with acceleration and deceleration. It sounds "electrical" in nature. Is this normal for this car (my first hyrbid)?

[Chucksrt]

Where does the sound seem to be coming from? Is it only at highway speeds? Is it only on acceleration? That isn't normal. My 17 has a similar type of sound but it happens more noticeably at lower speeds. It drives me nuts. When inspecting mine I found that when the dealer replaced the rear coil due to a misfire code I had, that they left a support bracket loose (unbolted) that secures to the back of the engine. I pried it away from the engine with my fingers and I thought it went away but then it came back. Im not sure if it had anything to do with it or not but either way I'm going to try to get back under there one nice day and re secure it with a bolt like it should be. My noise almost sounds like an exhaust type of viberation sound though.