My limited had a whine when it was new. It went away at around 10k miles.

There is a really lengthy thread about this on Tacoma World for the 3rd generation. The reasons are all over the place where the diff wasn't filled all the way from the factory to simply the type of design used. I would venture to guess the design is similar if not the same between the 4R and Tacoma so it may be worth a look.

Happy reading! 3rd Gen Poll: Rear End Noise howling when feathering throttle | Tacoma World

I owned a 2005 SR5, it had the same noise that started around 5k. I had a 2016 SR5, with the same noise that started after the first oil change at 10K. In both cases it was determined that the noise was coming from rear differential but nothing could be done as it was considered normal by TOYOTA. In other words, it is a *FEATURE* not an issue!

It was very frustrating dealing with the dealer to address the noise so in the end, got rid of both after living with it for 58K and 43K respectively. I bought a third one but this time I went with a TRDORP with a locking diff. So far I have 10k miles without the dreaded rear diff. noise however, it has a different noise issue that i think is related to dragging front brakes.

If I were you, I recommend you live with it or get rid of it to save your sanity! It will drive you nuts. It is unfortunate, that Toyota won't address this seemingly prevalent issue via a less stressful and time consuming means.

mine does it, exactly as described on this thread.

2015 trail edition (with rear locker). 90,000km.

between 60 and 80kmph, if I am applying the throttle lightly (as I pretty much always am between 60 and 80), it quietly howls/whines. The moment I let off the gas, it goes away.

I've been living with it since last summer. I can't tell if I only noticed it when I got rid of some other noises, or it just started then. It drives really well. My gas mileage isn't great, but it's not horrible.

I just assumed it was the pinion bearing preload washer.... but some of you guys have had the rear and replaced with the same noise afterward...?

Per my above post, new differential did not fix the problem. So, either the replacement differentials suffer from the same problem, or...the whining is not coming from the differential.
But since the whining ceases when you let of the throttle, that signals (at least to me) some kind of “lash” in the drivetrain SOMEWHERE.
Any mechanics on here want to chime in on the cause?

So I purchased a 2020 Off Road Premium, up from my 2018 Off road, because I wanted to new features, radio blah blah blah. I live in Colorado, and had to start using the 4 wheel drive almost immediately. Noticed a whine, under deceleration, then to a howl/moan/roaring noise between 30-50 mph in 4 wheel high, under acceleration. Thought maybe tires, lifted the vehicle with the same kits they charge 12k for on the new ones they sell here, noise still present. Changed the needle bearing to the ECGS clam shell bearing, and noise is still present. Take it out of 4 wheel drive and noise goes away, take foot off accelerator pedal, noise goes away, over 50 or under 30 in 4 wheel hi, nothing. The vehicle now has 3500 miles on it, and I am set to drop it tomorrow morning for a resolution. I have driven so many 4 wheel drive Toyotas over the years, the is my third Runner, new one every 2 years as I used to work for Toyota, had three tacomas and a FJ Cruiser, and have had all of them lifted and never one single issue. I am super in tune with my vehicles, so this is disturbing, and I will go all the way up the corporate ladder if this doesn't get fixed. It is definately in the differential, as I can also feel it in the steering wheel and the floor panel under the driver side. I am not sure if this is the same as what you guys are having an issue with, but I will let you know what ends up happening.

2016 SR5 with 35k and I have the exact same ‘whine’ mine is only under load (when I’m getting on the freeway or passing cars) above 4K rpmish


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Ok guys, as mentioned, my 2019 4-Runner had a whine/howl at hwy speeds. There was a TSB for replacement of rear prop shaft and mounts. Work was done and noise is gone.

Bumping this thread.

I've a 2019 TRD OR that exhibits the OP symptoms 100%. I'm not sure if this is a new sound or was always there.

Those who have posted in this thread with similar issues, were there any updates?

I've a dealer appointment on Thursday but not sure if much will come out of that.

Bought a new 4 Runner a week ago- has 300 miles on it now and when I hit 20 MPH I hear a whistling sound. Can't tell exactly where its coming from as you can hear it on driver, passenger and back passenger areas. It gets faint at 60 MPH. Noise isn't constant- but enough to drive me crazy. I've read where several Tacoma's have this issue-
I had a 2017 same body style and all never heard a noise like this.