Humming only in auto mode only on deceleration

[wyomingcowboy]

I have a 2011 Yukon XL, stock everything, and have recently noticed a humming sound that seems to be coming fromn the front driver's side area. It only happens in auto mode, and only on deceleration. I haven't been able to spend the time diagnosing much yet but we will have a lift installed early next week and that will help a ton. I have read that it is common for the clutch pack in the t case to wear out and make noise. I was hoping that someone else here has fixed this same issue and could tell me what they found. Vehicle has 234k miles and is still in great shape. My wife drives it mostly and uses the auto setting most of the winter here, which can last from October - May.
TIA

 

[petethepug]

What device, feature, component of the truck is in Auto mode? Assuming the xfer case right?

 

[B-train]

You are probably hearing transfer case noise from the clutches, or possibly some front differential noise from the axles being engaged and ready for 4wd. I'd advise to only use when wet, icy, or snowy. Leave it in 2wd for dry days.

Check the condition of the front different oil. These are notorious for getting dirty quickly. If it hasn't been done in many miles, you'll probably have a silver colored oil that comes out when you drain it, along with a fur sweater on the drain plug magnet. If that's the case, plan on changing it 1 or 2 more times in quick succession to clean it out. Drop it after a drive when warm.

Check the condition of the transfer case fluid as well. It should be bright red. If it's not, then drain and refill. New fluid will help the clutches work better and be less sticky on each other.

 

[wyomingcowboy]

What device, feature, component of the truck is in Auto mode? Assuming the xfer case right?

Correct

 

[Doubeleive]

I would start by checking the hubs first to rule them in or out, easy enough to do that without a lift, just need a jack
perhaps pull the drain plug on the front diff and check for metal, of course have some fresh gear on hand to refill.
if there is no metal and it just makes noise then go from there....... used front diff's can be had for $650 all day long,,,, cheaper than a rebuild.