I know the words auto 4WD should be self explanatory but for me they are not. I did try a search and found very little pertaining to what I am looking to find out.

What exactly does auto 4WD do when engaged? I noticed when I would engage 4hi I would get a clunk somewhere in the drive line signaling that the T/C was locked into 4wd. I notice that same clunk when Auto 4wd is pushed. BUT when pushing the 2hi button while the truck is in auto 4wd I don't even get a flash. Just 2wd lighting up. Same thing happend when I put it in 4hi from auto 4wd.

With winter weather quickly approaching I need to know and understand what each one does, and best driving conditions to use said 4wd's in. I don't have an owners manual or else I imagine it would explain itself.

I have noticed with the wet weather here that in 2wd I can of course spin my tires in wet conditions. In 4hi I can not, and in auto 4wd I can not. I would expect atleast some sort of slippage when in auto 4wd due to the fact that if it worked similarly to an AWD system that it would first have to notice wheel slip before engaging the other drive wheels.

The only other 4x4 I have ever noticed with such an unoticeable shift between 2wd and auto 4wd would be an 03 explorer I had for a few months.

Can anyone define what auto 4wd actually does and how it works?

I really hope this post doesn't make me seem like a complete fool.

 

With Auto 4wd engaged it allows the truck to automatically engage the front wheels when it senses the rear tires slipping. Used it only once on an 01 Suburban 3/4ton we had.

 

Hardly makes it a subaru, subaru is full-time AWD, with a bias diff.

 

Auto 4wd makes your blazer a subaru basically. We use it whenever there is a chance of icy roads (pretty much all winter here), and turn it off when the roads are bare. 4 hi is 'real' 4 wheel drive and shouldn't be used on asphalt.
I noticed that it shifts faster into and out of auto, probably because nothing mechanical is being engaged yet.