Intermittent Humming Noise From Rear

[TC245]

I've a 1999 Avalon with 110k miles. A few weeks ago, a low humming noise started appearing. It sounds like it's under the rear seats or trunk. The noise is intermittent. There may be 10-30 minutes without it, 1-10 seconds of noise, then it just comes and goes at odd intervals. It seems like it will stop when I let off the accelerator, but that may be a coincidence. I'm thinking fuel pump. Anyone else have any other ideas?

[bobstcyr]

this may seem dumb but I did experience something similar on my 97 avalon.... it turned to the caliper dragging and it prematurely wore out the pads..... may be worth a check?

[TC245]

I'll check the calipers.

The humming sounds kind of like rear-wheel drive differentials do when they're making noise. Only the Avalon is front-wheel drive. It's definitely coming from the rear, and most likely the passenger side rear. I had a friend sit in the back seat today while we drove around.

The humming is occurring more and more frequently and lasting longer - up to 30 seconds at a time today. It definitely only occurs during steady-state driving. It always goes away when I change the accelerator position - either lifting my foot or pressing. It occurs at different engine speeds, in different transmission gears, and at different vehicle speeds.

From a stop, I can punch the accelerator, squeal the tires and hit 60 mph fast. There's no change in how the engine is performing.

I've a long trip planned just after Christmas and thus am concerned. If I cannot find it myself, I may just take it to the dealer later this week.

Any help is appreciated. Thanks.