I have a 99 Accord with 42,000 miles on it. I just started to hear a moaning sound coming from the back whenever I back up. I does not seem to be the brakes, as the noise
is there without using the brakes. Also, it does it in gear or coasting. There is no one in the trunk or back seat ( I read the other noise complaints). It almost sounds like
a vacuum leak. Does anyone have any ideas before I take it in to the shop ?

 

Does it have rear disk brakes? Check em.

 

I had an Integra that did that - rear brakes. It was a moaning sound that almost sounded like a musical tone. Only happened when I backed up, went away when I applied the brakes. And it didn't sound like the screetching I expected from the brake-pad wear indicators.

Wait a couple weeks, it will soon develop into that screetching sound that tells you your brake pads are worn out.

Or better yet, check your brake pads. Check all of them, because sometimes sounds travel funny in a car & this might even be your front brakes.