Just to be clear, you put it in 4 high and the front axles are spinning but they are not driving/pulling the vehicle? If this is the case, it sounds like the actuator is not actually meshing the gears to engage it in 4WD.
I believe you have full time hubs on this vehicle which means you do not engage and disengage the front axles. This means the axle shafts will spin whenever the tires are moving. The way you achieve 4WD vs 2WD is you engage the actuator and this meshes the gears in the case which links the front and rear axles.
Have you set the vehicle on jack stands and then put it in gear to see if the front tires spin? If not, this is what I would do next.
https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely
Take a look at the info below and let me know if you have questions but I would replace the actuator and retest.
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Friday, May 14th, 2021 AT 11:20 AM