Avalanche 4wd not working in 4 hi and 4 lo

[pastorj]

I noticed a few weeks ago in a snow that my 4wd was not working. Hearing the transfer case kick in, especially in 4 lo, after reading I thought it was my front axle actuator. I bought a doorman one. Since installing it I now notice both the transfer case motor/actuator and the front axle actuator whining to do their job. However, what seems to be a change. Today I got in some more ice/snow. Nothing but 2 wheels working in 4 lo and 4 hi. I also then tried auto 4wd and it works. So I am not sure what it is.

One thing to note, when looking at the new and the old actuator the new one has a full hexagon plunger inside the tube. The old one looks identical but the plunger inside the tube is a little different shape. It looks more like a square with the corners knocked off and the tube shape is still the hexagon. I wonder if this could be the difference.

 

Please help!