4wd won't engage. All motors run. Indicator light shows its in 4wd but it's not!

It doesn't turn in 4wd but does in 2wd.

Then the transfer case is working!... Suspect front axle actuator is not engaging the front differential... IF you are positive is is not going into 4 WD... That's about all it can be. . . https://www.youtube.com/watch?v=S55ZEQjmKnw

I already replaced the front actuator. This is what I've done. On jack stands in four wheel drive front tires spin but on the ground in snow on ice in 4wd only back tires spin. Its like when there is just air its fine but with any kind of resistance it doesn't work.

Well now since you finally posted that info... Possibly transfer case internal shift fork problem... Disassembly required.

How do you tell?

This is the easiest way to explain.. Jack up back of truck and put on jack stands... Front end on ground... Start engine and select 4WD high... put shifter in drive... STAY IN DRIVERS SEAT!!.. Have a helper look from the side to see if front driveshaft is turning.... **BE CAREFUL!!** .. IF shaft is NOT turning ... Read over what I've posted again... Post results for more info.

Front drive shaft does not spin with rear end off the ground and front end on the ground in 4wd.

Suspect transfer case internal shift fork worn and not fully engaging 4WD... It happens... It is most likely not a DIY repair at this stage.

OK thanks for the info and your time! I guess I'll have to take it in!

That's probably the best thing to do... Let us know the outcome... May benefit other with same problem.