First off, I am not a mechanic so please pardon my ignorance. I have a 2006 Suburban 2500 with 245k miles. I have always been able to hear the difference when switching from 2WD to the Auto 4WD setting because you can hear the front axles spinning. Now however, it sounds like that when the truck is in 2WD and there is no discernable change in sound when shifting between 2WD and Auto-4 or even regular 4-Hi. Is there a possibility that those front axles might be engaged while in 2WD and how would I determine that? Thanks for any help.

 

Unless you have locking hubs, the front axle is always spinning. Otherwise the vehicle wouldn't go anywhere.

If you want to check if it's stuck in 4WD, make the rear wheels spin. Put them on some ice or snow

Have you been servicing your axles and transfer case?

 

Thanks for the reply. This is why I thought I would try this forum, if I make myself out for a fool it's to people who I don't know.
So I have never been able to understand how the Auto-4WD setting actually works but someone told me that the axles would be spinning in that setting. Maybe it's that the axles are engaged with the front diff but no power is delivered until there is slippage in the rear? I would like to understand it. I know that the full 4WD is not engaged because it doesn't crab around turns on dry pavement.
I'm relying on my mechanic to service the vehicle, when it goes in for oil and lube I assume he's oiling and lubing whatever needs to be oiled and lubed. He thinks this noise I'm hearing is tire noise but I've driven this truck 150k miles 40k of which have been on these tires and the noise just started. Maybe I need a new mechanic.

 

Personally, I take responsibility for keeping track of scheduled maintenance of my vehicle. It's why they put it in the owner's manual. I don't rely on anybody else to care of my belongings.



https://charm.li/Chevy%20Truck/2006/...d%20Operation/

I don't know which system you have. You'll need to crawl underneath wipe off the identification plate and read the model number.