Oil pressure Gage

The oil pressure gage has never worked on my Camaro. It just points strait up and never seems to move. Im asuming the sending unit's gone, but is there a way to test the gage first. I would think that unplugging the wire going into the sending unit and grounding/ungrounding it with the ignition on would cause the needle to move from one extreem to the other, but im afraid of shorting anything out, should I give it a try?. Also there are two sensors coming off the oil filter housing. A big one and a small one, the big ones the sending unit for the gage, and the little one's for the idiot light right?

Thanks,
Pat

The litttle one is for the "fuel pump cut-off switch", in the event of a sudden loss of oil pressure it would save the motor.
If you have never replaced the oil sender, I'd do it b/c they have a habbit of reading low over time and eventually hitting zero and leaking oil.