nmrydr

Hello everyone.
I've had my '97 Mustang GT 'Vert for 2 years now. My tach has never worked. I have the Ford service manual and the electrical and vacuum manual. I have power, ground and I'm supposed to hook up some funky Ford tool to check signal.
Is there a way to check for signal from the computer without taking it in to a dealer? I know which pin is supposed to provide signal just not sure how to check it.
Any help would be greatly appreciated.