2001 Yukon XL 4x4 only works when truck suspended in air

[saltednuts]

2001 Yukon XL SLT 1500 5.3

 

4x4 works when truck is jacked up on a lift (all tires are suspended in the air) however when the truck on the ground, the 4x4 isn't working. The rear tires have power yet there is nothing coming from either of the front tires. Anyone else have this issue??? I have taken my truck to a mechanic twice now and they have no idea.

[saltednuts]

Replace the Encoder Motor. They have a "brake" in them that gives out and does not keep it fully engaged. I personally have probably replaced close to 100 of them for the exact concern

That gives me hope. Is it an easy part to test to see if it is working properly before I buy a new one? Also, is it an easy part to replace?

 

I appreciate all the help.

Replace the Encoder Motor. They have a "brake" in them that gives out and does not keep it fully engaged. I personally have probably replaced close to 100 of them for the exact concern

That gives me hope. Is it an easy part to test to see if it is working properly before I buy a new one? Also, is it an easy part to replace?

 

I appreciate all the help.