Greg,
You would have to connect the tach to the "-" side of the coil, +12 volts, and ground. So the answer is "NO".
There is no simple measurement that you can make out of the car. I have taken the tach out of the cluster and run leads to the appropriate connections to check things out. I left the tach sitting under my hood in a place that was visable from the driver's seat(hood up, of course).
Mike