What runs the tach on a 1994 Chrysler lebaron?

The tachometer in a 1994 Chrysler LeBaron is driven by a signal from the ignition system. Specifically, it receives a signal that's proportional to the engine's crankshaft speed. This signal is usually derived from either the coil pack (most likely in your case) or the distributor (less likely, depending on the engine). The signal is then processed and displayed on the tachometer.