zz2h33

Screwball not sure if your post was directed at me or not but I wasn’t asking for a lesson on how the 4wd/auto system works in these trucks. I know very well how they work and I know how it’s been stated multiple times in this thread because people like to repeat things to try and sound smart. I also stated very clearly that I DO NOT drive in auto. I’ve own two GMT900 trucks and a 360 (trailblazer) all with the same system and none of them had this noise in addition to the K2 I rented for a while did not have it. What I hear in this truck is ABNORMAL compared to my experience with these trucks and that’s what really has been stated MULTIPLE TIMES in this thread and this is what the thread is really about. So thanks for stating the obvious, again, for those that don’t know what is actually spinning when in auto or full 4WD ...but it’s absolutely no help.

Checking in here with the same issue 2014 Silvy 6.2L. Audible humming noise with AUTO or 4H engaged under acceleration and goes away while coasting. It is quite loud even my passengers have asked if something was wrong. I bought the truck with 40k miles now have 75k and have always had the noise. And no I don’t drive in auto 24/7, just use it occasionally for what it’s intended for. Seemed to get worse after putting taller tires on and leveling kit. I rented a 2018 Silvy a few months back and tried it in Auto just to see and it was quiet with zero noise. So i’ve been worried and basically waiting for something to majorly break until I ran across this thread where it sounds like it’s fairly common. My questions are: 1) could this be related to final gear ratios in our trucks experiencing this? I have the max towing package and since adding taller tires it has definitely compounded the noise. 2) have any of us experiencing this noise actually had anything break such as not engaging auto or 4wd and the service 4wd message? 3) have any of us experiencing this noise been able to pinpoint it and have it fixed?