Is there a way to test the 4wd actuator and the electric shift switch. on 1999 Chevrolet Silverado 1500

My 4wd shift does not work I dont know if it is the dash switch or the actuator on the transfer case. Is there a way to test both items to determine which is bad?

Asked by for the 1999 Chevrolet Silverado 1500
Yes there are tests hard to explain without your having axcess to the wiring diagram and illustrations. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate
Its great information pretty easy to follow.