Which motor & what coil ?
Walker liked to fit Kohlers
Kohlers have a few different ignition systems
Most coils have a Hall Effect timing chip in the coil ( replaces points, remember them ? )
The chip is very sensative and if ever exposed to any battery voltage it will fry
Even some cheap Ohm meters will fry them
The kill wire is a ground wire so is either open ( to run ) or ground ( to stop )