02 Tahoe 4wd Diff Actuator

[DNChassis]

Everything I have read suggests this is the issue with my 02 Tahoe. How do I go about isolating this issue before I order the part to replace it. Can I screw it out then press the 4wd switch in the cab, check the wiring at the Actuator for voltage, and watch to see if the Actuator moves? I read that you cannot do this with the encoder motor because it will harm it.

Thanks,
Stan