Darrel,

I've just received a reply from my mate


The pulses appear to be 0-12-0 "square" wave, but not 50/50 duty cycle. the 12 volt pulse is much less than the 0 volt. I've found that a similar unit off a Ford uses a hall effect transistor and a multipole magnet, very similar to a heli throttle govenor.

Frequency...difficult right now to get you an accurate figure for the maximum..minimum is easy, it's 0....LOL. I can't imagine it would be more than 1 khz maximum on the unit I have.
Does this help to determin the adjustments for the code