[31 Ford A]

Can I bench test a stop light switch that is an inline switch activated by the pressure from a hydraulic cylinder-? I can feel the plunger/shuttle go in and out, when removed, by pushing a nail through the hole where the fluid activates the switch. If I push the plunger/shuttle in and test across the two electrical contacts, should I get a reading on my continuity meter which would show that the contact was closed thus completing the circuit-? I have tried doing this but I get no reading whatsoever-? I have also tried placing this and another switch I bought in a 12V circuit to see if this would activate a 12V test light when the plunger is activated. It did not. I would think that by pushing in the plunger-shuttle by had it would simulate the pressure from hydraulic fluid and indicate the switch closed and completed the circuit-? Or, do I just have a couple of bad switches-? This problem is driving me nuts. My guys at the parts store think I don't know what I'm doing by buying all these stop light switches. I'm beginning to agree.