What engine? What year? What ignition system?

I'm currently using the "Hot Spark" points elimination kit (essentially a "Hall Effect" pick up which mounts inside the distributor) on my '72 M115 and on my '74 M110. I'm picking up the tach signal directly from the negative side of the coil. On my '85 M117 with the stock ignition system I'm also getting the tach signal from the negative side of the coil.

Which version of the firmware are you using? If it is V3.x or above you must set the pick-up choice to "basic trigger" in the ignition set up choices as the default setting is "trigger wheel"

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