Humming noise when tightly turning steering wheel, only during cold start and go?

[JKeller]

Engine warm up makes no difference (at least on my Tahoe). The noise occurs until the differential is warmed up, and the engine does not warm up the differential. It needs to be driven to warm up the differential.

I changed the fluid in mine today. I'll update with whether it made a difference after I put some miles on it.

It took a little bit of driving but the noise has gone away with the fluid change. For reference, mine started making noise around the 45k mile mark, which is when they recommend fluid changes in the tranny and differential.

 

[B520044]

I have this exact issue with my 21 AT4. Its been doing it for probably 8k miles; I now have 41k miles. I'm also due for new tires, so hopefully they can knock this out during the tire install. Thanks for posting.

 

[Autotrends]

What type of gear oil did u use and how much? I can’t find any info on it

It took a little bit of driving but the noise has gone away with the fluid change. For reference, mine started making noise around the 45k mile mark, which is when they recommend fluid changes in the tranny and differential.

 

[Chris01234567]

Mine comes back when temps are below 40 even after the gear oil was changed. Absolute trash.

 

[R32driver]

I’ve just recently started hearing a strange noise coming from the rear only when the vehicle first comes out of the garage. This must be what I’m hearing. I guess it’s time for warranty visit number 4 to the dealer

 

[R32driver]

Stopped in at my local dealership service department (small place in a small town) and they said they’ve not yet seen that tsb and the rear dif fluid is indeed on back order. Said they will call when it arrives

 

[JKeller]

What type of gear oil did u use and how much? I can’t find any info on it

I wanted my mechanic to use Amsoil, but they said there isn't an Amsoil alternative available yet. They had to buy the GM fluid directly from a dealership. Sorry but I don't know what weight that was, just that they used what the manual recommends.

 

[guyhamilton]

must be a T2 thing, I have had front differentials for 25+ years (multiple GM vehicles) and only had 1 make noise when 4wd was "engaged" and moving any direction, regardless of temperature.

My 2wd 2021 suburban is doing it when warm also. The loudness varies though. Is it the electric power steering unit?

 

[Doubeleive]

My 2wd 2021 suburban is doing it when warm also. The loudness varies though. Is it the electric power steering unit?

there is a TSB on the front diff's making noise for thr 2021+ I guess the fix is a fluid change of some form

 

[WalleyeMikeIII]

there is a TSB on the front diff's making noise for thr 2021+ I guess the fix is a fluid change of some form

I thought that was for g the rear diff (mechanical locking version)