Assuming you are referring to the transfer case control module (TCCM) on a Chevy Silverado:
There is no easy way to test the TCCM, as it is controlled by the vehicle's computer. However, there are a few things you can do to check if it is functioning properly.
First, make sure all the fuses related to the TCCM are intact and working. Next, check the wiring harness for any loose or damaged wires. Finally, have a professional scan the vehicle's computer for any codes that may be related to the TCCM.