[Walt Fricke]

The tach signal from the DME to the tach is a nice square wave, 5V I think. It should work with your earlier tachometer, but if not, use a tach adapter on that signal. It has all the very little current needed.

Don't mess around with running a wire (or finding an unused one) from the engine up to the tach. The DME knows very accurately what the engine speed is at any given moment - that's how it adjusts spark and fuel from the throttle position and other inputs.