I had my 2002 suburban LT (378,000 miles) on the beach (very soft sand) about a year ago in 4x4 low and the front axle stopped receiving power. I was towed off and since then 4WD has never worked. I can get high and low to "engage"

(and low is working as 2WD low) but only the rear axle is driven. If I put the vehicle up on jack stands and put it into 4-Wheel all four wheels turn. Upon placing the vehicle back on the ground only the rear wheels are powered. Any ideas? Feel like I'm probably going to need to install a third transfer case......

Note: have put 3,000 trouble free (2WD) miles on vehicle since 4WD stopped working.

 

usually shift motors go out. Check the connections on it.

 

Broken chain since it is shifting between hi and low.

 

That's a butt load of miles, and yes, I agree.