Whining noise when letting off of the accelerator

Hello, first post here and I just got my first Tacoma. I have an issue that I’m wanting to get an opinion on possibly without taking the truck to the dealership and making a fuss. My Tacoma seems to make a whining noise that comes from somewhere in the engine bay either at moderate to higher speeds when I let off of the gas pedal just after accelerating. But it also does this even when I have the pedal down at higher speeds. Does anyone know what this could possibly be?

 

automatic trans?.............welcome aboard

 

Yes it is and thanks.

 

Trying to think of whining in/near engine bay. First thought was 3rd member in rr end but then that isn't engine area. Does it seem like a certain gear or does it do it with overdrive on or off or both(if it has that) Maybe the alternator whining but that would throw a charge light if really bad other than the bearings in it going out. Other than that I would have to ask how many miles on truck and maybe one of the 3 belt tensioner pulleys starting to die. Kinda hard to tell without hearing it. All kind of things come to mind. Guess if it isn't constant then probably not some of those things...only when letting off gas makes me think driveline things. Wheel bearings would be constant sound at whatever speed, not just when letting off gas...........hmmmmmmmmmmmmm????

 

To answer some of you leave questions, it doesn’t have overdrive. It is 2WD, it’s has just under 82,000 miles on it. Sounds like it could be a lot of things

 

It's probably the secondary injection pump just doing what is supposed to do. Also I would be a good idea to check your trans fluid. Some late models have been known to leave the factory with low trans fluid.

 

Doing it with the a/c on? My trucks compressor makes noise while coasting at highway speeds. It makes noise all the time, but it’s a whine/howl at highway speeds. I need to replace it before it grenades and takes the evaporator and everything with it. Also check all your idler and tensioner pulleys.

 

I haven’t tried without the a/c on, perhaps I’ll try that.