Hooking up the Haltech F5 and it says to connected it to the negative side of the trailing coil. (Figure that to be the black/white wire on the two prung harness). I installed it on the yellow blue tach signal since I assumed it was 12V square wave output?

Any ideas.

Thanks,
Ian

 

The Black/Red wire is the +12Volt side which is battery and constant.

The Yellow/Blue is the switched ground side, and has a basic square form and is correct.

Another place to attach a tach lead is to the ignitor output before it goes to the coil. Same signal but different color wire; light green/Black.

 

Thanks,

But I need a 12Vdc square wave output. The tach I found out is 0-5v.

?

Thanks,
Ian

 

Those locations work fine with the J&S, and Autometer shift lights. When the switching transistor is conducting, the voltage should be near ground potential.
When open, it should be near 12volts.

Usually pulse detectors/counters are not so fussy. Have you even tried it?
Maybe you are not connected as you think you are.

Install a Crane HI-6 and use it's tach output.