Weird humming noise when in reverse

So I own a 2003 Toyota Tacoma prerunner sr5 2wd v6. Every time I put my truck into reverse it makes a weird humming noise. I talked to some coworkers, they told me the sound is coming from the transmission. It drives smoothly and everything is fine. It's just when I put it into reverse it makes that humming sounds and gets really annoying. Has anyone run into this problem? I wanna know if it’s a quick and not so serious fix or if the transmission is going bad. Please help!!

 

Manual or automatic?

 

punctuation is your friend.

also, got a sound clip of the "humming"? sure it's not a grinding kind of sound?

 

Just don't go in reverse and you won't have that problem...JK!
How does the fluid look,when was the last time it was changed?Try changing the fluid and seeing if that helps.

 

It’s an automatic

 

Topped of my trans

topped of my transmission fluid like 2 days ago still making that noise though

 

No it’s not a grinding sound

 

Topped off isn't changed, though.

How many miles? Trans ever been serviced?

 

I’m at 169000 and not that I know of

 

I've never had to "top off" my trany oil, except that time I installed a trany cooler and spilled a little.

These aren't mid 70's domestic pickups that need to be "topped off" every other fill up.

That tells me you've got a leak or something and need to get it fixed ASAP.

 

If you're auto trans has never been serviced in 169k miles then it would be best to take it into a reputable mechanic in my opinion and see what they suggest. 15 years and 169k miles on the original auto trans fluid probably as something to do with it. But this far along it might be too dangerous to do a flush; a drain and fill is likely the safest bet.

 

@gearcruncher could shine some light on this I bet

 

I’m gonna have to try that out then and hopefully that helps makes the noise go away

 

Without a video clip with sound , my best guess from the armchair is the pressure regulator valve inside the transmission resonating or what some guys describe as a buzzing .
When you select reverse , the transmission needs maximum pressure to hold that gear . Its a tell tail sign that there is an issue with the hydraulics inside the transmission .
Others above have suggested a transmission fluid change and I agree .
You mentioned the fluid was topped off ? How long were you running around with low trans fluid ? How much fluid did it take to top off the transmission ?
169K without a trans inspection and fluid change is pushing it
There may be some wore out valving that needs to be checked out.
You can select reverse and check the pressure with a pressure gauge
When you have the pan off and inspecting your filter and magnets , why not try this
https://www.tacomaworld.com/threads/sonnax-zip-kit-a340-late-installation.435019/#post-14714790

Here is a write up involving your transmission

https://www.tacomaworld.com/threads...sions-write-up-your-4-speed-automatic.325531/