The vacuum actuator used on the 10-pin cruise control system has two items to test. 

1) Ensure the unit holds a vacuum. 
There are two ports on the actuator. One connects to the engine's vacuum supply. The other port is a vent. You'll want to connect a vacuum gauge such as a MityVac and verify that the diaphragm holds vacuum. 
2) Check resistance
There is a two pole connector on the actuator. Note the orientation of the connector and disconnect it from the actuator. Take your multimeter and measure across the pins of the actuator. It should be between 12 and 22 Ohms. Be sure your meter is set for the appropriate range. 

As long as these two tests pass the actuator is in good shape!