327i Tachometer off speed(reference) sensor?

[kistler#7]

Trying to get the tach working on my 2.7i project, I had it wired to the negative electrode on the ignition, but I soon after blew a transistor in the megasquirt that runs the ignition...so I'm looking for other possibilities for a tach signal, and I still have the two sensors on the bell housing that are no longer in use. One of these is a speed sensor, could I tap into this for a tach signal? Thanks

[jlevie]

What tachometer are you using? The OE tach expects, as I recall, a 5v square wave at a rate of one pulse per ignition firing.

[kistler#7]

Thanks, any idea if any of the sensor wires give this signal?
Yes stock tach