whining from rear

I posted this question a couple of months ago, but the situation has changed a bit. For three months, we have had a high-pitched whine that seems to come from the rear driver's side. The whine only happened between 35 and 45 mph (not varying with rpm, only mph). Yesterday, the whine suddenly got very loud for about 10 seconds (while we went about 40 mph). At the same time, the ABS light came on, and the fuel gauge dipped slightly and went back up. The noise is now quieter as usual, but happens at lower speeds (about 30 to 40 mph). The ABS light went off after turning the car off and then back on again. Any ideas on the root problem? One idea was the wheel bearings. Another the fuel pump or filter???? Why would either of those cause the ABS light to come on?
Thanks.

My wild guess would be some debris hung between a wheel (ABS) sensor and the toothed ring.

If you have drum brakes on the rear.....you can inspect the gear / sensor for the ABS by removing the brake drum. You can clean the brake dust with brake cleaner. You might try rotating the tires to see if the whine moves.....or changes.
I do not know how a tire would cause the ABS issue......but is possible that it is a separate problem.

I would recommend having the rear wheel bearings checked . I had a check done on my car last spring in which they found "extra play" in the rear wheels....caused by the bearings needing repacked. The bearings were not defective....just needed repacking.
If that is the case for you......then that could be how an ABS error was logged.......due to extra movement......

One solution is to either have her stay home or sit in the front instead.

I also had an ABS lt and Trac OFF lt while driving my '99. It was raining at the time, and I'd been on some muddy roads. (Who needs a 4X4 when you've got a W-star?!!) I assume that this was no cause for alarm and that something was preventing a sensor from reading. It's gone off since then. Am I making a proper assumption or should I have it checked out?